Oxygenator fish tank

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Manually Generating Oxygen in Aquariums

In a power outage, an aquarium is safe for some time without filtration, but the inhabitants cannot survive for very long without the oxygen normally added by the powered air pump. You can manually add oxygen easily if you do not have a battery-operated air pump or an emergency power source to run one. The manual method also helps keep the water circulating. Learn what to do when the power goes out.

How to Manually Oxygenate Your Tank

You can add oxygen to your tank by slowly pouring water into it from some height above. The water will pick up air en route as well as drive oxygen into the tank water. How much oxygen is added depends on how high above the tank you pour the water and how many times you repeat this procedure. Here are the simple steps:

  1. Take any type of clean cup, pitcher or another container, scoop out and fill it with aquarium water.
  2. Hold the filled container some distance above the aquarium, and pour the water back into the tank. Repeat this process numerous times.

There is no set rule on how often this should be done because every aquarium is different. You'll need to judge for yourself at what intervals each hour is going to be best for your system. When in doubt, go ahead and do it more. If the fish start coming to the surface gasping for air, it's definitely time to aerate some more.


  • Pouring water can stir up the substrate. To avoid this, place a small plate or bowl in the tank (one heavy enough to stay at the bottom) and pour the water over this area.
  • If you are using the floating hot water container method to manually generate heat in the aquarium, periodically pour some of the water over the top of the containers. Most of the heat generated from the floating containers will stay near the surface, so this is a good way to get the warm water circulated.

Battery-Powered Air Pumps

You may have battery-powered air pumps on hand for just such power outages. Note that most battery-powered air pumps are not very powerful and will not drive air very far into the tank. Be sure to test them regularly so you know you whether or not they will be reliable in an emergency. The best and most reliable battery back-up air pumps are the ones which run constantly on AC power, then automatically switch to the air pump's internal rechargeable battery when the power goes out. These work very well if you don't happen to be at home when the power goes out.

Test Your Water for Ammonia

If your system ends up being shut off for a long period of time, due to the lack of filtration it's important to periodically test the water for any sign of ammonia. If ammonia does start showing up, you can be ready to handle the situation to prevent ammonia poisoning by having an ammonia reducing product such as Kordon's AmQuel on hand.

Sours: https://www.thesprucepets.com/manually-generate-oxygen-in-aquariums-2924721

You might not be able to see it, but it’s actually one of the most important parts of your aquarium.

No, I’m not talking about the canister filter hidden away underneath your aquarium.

I’m talking about oxygen.

It’s funny – one of the only times you will think about the oxygen in your aquarium is when it isn’t there.

And by then it’s too late.

So sit back as I teach you everything you need to know about this important aquarium ingredient.

Where does the oxygen in your aquarium come from?

Even though H2O (Water) is part oxygen, it is bonded with hydrogen – essentially locked together, thus making it inseparable.

Your fish can’t breath this.

So if that’s the case, then where does the oxygen that your fish breath come from?

Believe it or not, plants and fish actually breath the exact same oxygen as you and I.

In order for your fish to “breath” oxygen, it needs to get inside the water. And how it gets there is actually very interesting…

The surface of your aquarium is always in contact with the air. And it is here, at the surface, that oxygen enters the water through a process known as gas exchange.

The reason it is called gas exchange is because the air and water do a trade. The water in your aquarium swaps carbon dioxide (CO2) for the oxygen (O2) in the air.

I find that a diagram makes it much easier to understand…

gas exchange of oxygen and carbon dioxide in aquarium at surface water diagram

Pretty simple, huh?

Since fish breath in this oxygen and give off carbon dioxide, this exchange is a continuous process.

It is also worth mentioning that the larger the surface area of the water, the more efficient the gas exchange.

So a larger tank is much easier to oxygenate than a small one.

Once the oxygen enters the water, it is referred to as dissolved oxygen. When discussed online, dissolved oxygen is often shortened to DO.

Now you may be wondering:

How much oxygen does your fish tank need?

Unfortunately, this is a difficult question without a clear answer…

Especially given that there are different factors contributing to how much oxygen can actually dissolve in your fish tank, including:

1. Water temperature – As the water temperature increases, the amount of oxygen that water can hold decreases. Tropical fish have less oxygen in their water than cold water fish.

2. Salinity – To put it simply, salinity is the measure of the amount of dissolved salts in your water. The saltier your water, the less oxygen it can hold. You can test the salinity of your aquarium with a refractometer.

3. Atmospheric pressure – The lower the air pressure, the less oxygen the water can hold. It may surprise you to learn that, all thing being equal, water in Miami (altitude 6 feet) can hold more oxygen than water in Denver (altitude 1 mile).[1]

Then there’s the fish…

Generally speaking, larger fish need more oxygen than smaller fish, while slower moving fish need less oxygen than fast swimmers.[2]

So, as you can see – the answer to how much oxygen your aquarium needs isn’t exactly clear cut.

That said, there are recommendations as to the ideal oxygen levels for certain aquariums, measured in Parts Per Million (PPM).[3]

Freshwater Fish8.3 PPM
Marine FishBetween 7.0 and 6.4 PPM

Please note that these are only loose guidelines and the previous factors I listed will impact just how much oxygen can dissolve in your tank.

But if your fish are behaving normally, and are not gasping for air at the surface of your aquarium, then it is a good sign that there is enough oxygen in your aquarium.

In fact, fish behavior and oxygen levels go hand in hand.

Which brings me to my next point…

How do you know if your aquarium is low on oxygen?

Water with lots of free non-compound oxygen dissolved inside

Above, you can see a picture of water that is high in oxygen.

The next picture shows water with dangerously low levels of oxygen…

Look closely…

Water with low levels of oxygen

Notice anything different?

I would hope not!

I don’t care how good your eyesight is, it is practically impossible to determine if water has an oxygen shortage just by looking at it.

While you could test your water for dissolved oxygen, which I will get to in a moment, there is one other way to determine if your aquarium has low oxygen levels…

By looking at your fish.

Your fish will behave differently according to just how much oxygen is in the tank.

The first sign that you have an oxygen problem is slower movement. At the first sign of low oxygen levels, fish will slow down and swim less. This is particularly noticeable in active fish.

As oxygen levels continue to drop, you will notice that your fish has trouble “breathing.”

Fish Fact: When oxygen levels in an aquarium or pond are too low, this is referred to as hypoxia.

If you look closely at the gills, you will notice them moving rapidly as your fish desperately attempts to get enough oxygen by passing more water than usual through their gills.

If the oxygen levels are drastically low, then the symptoms become obvious – your fish will gasp for air at the top of your aquarium.

Your fish will look noticeably distressed as they attempt to draw oxygen from the most oxygen-rich location in your aquarium, the surface layer.

If your tank is home to many different types of fish, you may notice that only a few gasp at the surface for air.

You should still be concerned, as those that are not gasping for air are probably stronger or require less oxygen – they too will eventually be affected by low oxygen levels if the problem is not corrected.

Fish show these obvious signs of stress when the oxygen content of water drops below 4 PPM. If the oxygen drops below 2 PPM, death will soon follow.

Fish like bettas, gouramis and paradise fish often take a gulp of air from the surface. This is normal behavior and should not be confused with fish that remain at the surface gasping for air with their mouths wide open.

So now that you know how to identify the problem, it’s time to determine the cause…

What causes low oxygen in aquariums?

Fish gasping for air at surface of water due to lack of oxygen

1. Overstocking

By far the most common cause of low oxygen levels in aquariums is overstocking – keeping more fish than is appropriate for your tank.

Each fish that you add to your tank needs oxygen to breath. And once you add too many fish, the oxygen in the water will be consumed at a faster rate than it can be replenished.

And the consequence is that there isn’t enough oxygen in the tank for your fish to breath.

Fortunately, the solution to overstocking is simple:

There are calculators available online that can help assist you with how many fish you should stock in your tank.[4]

Compared to overstocking a fish tank, the remaining contributors to declining oxygen are quite minor. However, when combined with an overstocked aquarium, these factors can be dangerous.

2. Plants

I know, it seems like a funny one…

Living plants use carbon dioxide (CO2) and give off oxygen – so how can they contribute to lower oxygen levels?

Well, here’s the thing:

Plants only give off oxygen when exposed to light, whether that’s natural daylight or the light from your LED setup.

When night falls, and the tank turns dark, the opposite happens – plants consume oxygen and give off CO2.

If your planted aquarium has reduced or no light for an extended period of time, the plants could deplete enough oxygen to affect your fish, especially in an overstocked tank!

Note: Algae is also a plant, and this problem can also occur in tanks with a heavy algae bloom.

3. High Water Temperature

As I touched on earlier in this article, warm water cannot hold as much oxygen as cool water.

In summer, the water temperature of your aquarium can spike – especially if it sits in direct sunlight, like near a window!

And when this happens, there is going to be less oxygen in the water for your fish.

If you notice that your aquarium temperature is higher, then you have a few options available:

  • Shade the aquarium from sunlight
  • Perform a water change with cooler water
  • Turn off the heaters until temperature returns to normal
  • Use a fan or aquarium chiller to blow cool air over the surface
  • Float a zip-close bag with ice cubes inside in your aquarium

4. Excess waste

Okay, so excess waste isn’t directly responsible for a lack of oxygen in your aquarium…

But it does kick off a chain of events that can lead to low oxygen levels, so I felt that it should be included in this list.

Fish poop, plants decay and uneaten fish food will rot…

Bacteria that feed on these waste products also require oxygen, further depleting the oxygen levels in your tank.

Excess waste can also lead to an algae bloom, which can also lead to oxygen loss.

Oh, and if that’s not enough, too much ammonia from waste can irritate your fish’s gills, making it more difficult to draw oxygen out of the water.

Long story short – don’t let waste build up in your tank!

5. Chemicals

Certain medications for fish disease and chemicals like water conditioners can have a direct impact on the oxygen-carrying ability of the water in your tank.

When using chemical additives, it is recommended you always read the instructions to determine if they will cause any negative effect, like lower oxygen levels.

How do you test the oxygen levels of your aquarium?

For hobbyists, there are two common devices used to measure the amount of dissolved oxygen in an aquarium[5]

Let’s start with the cheapest option…

1. Dissolved Oxygen Test Kit

Salifert dissolved oxygen test kit for aquarium

If you have ever tested the pH of your aquarium, you will be all too familiar with colorimetric tests.

Well, aquarium test kits work in a similar way, and can even be used to check the oxygen levels in your aquarium.

Simply add the drops to a sample of your aquarium water and compare the color to the chart to determine the amount of dissolved oxygen in your tank.

Generally speaking, the more expensive the test kit, the more accurate the reading will be. That said, being precise isn’t too important to hobbyists, who will generally only need a rough idea of their dissolved oxygen levels.

Each dissolved oxygen test kit is capable of performing multiple tests. The Salifert test, pictured above, is capable of performing over 40 tests.

2. Dissolved Oxygen Meter/Probe

Milwaukee MW600 Dissolved oxygen meter for aquarium

If you have the cash to spare, a dissolved oxygen meter precisely measures your aquarium in just a few seconds.

Stick the probe in your aquarium and the amount of oxygen in your aquarium will be displayed on the LCD screen.

While a dissolved oxygen meter may be more accurate than a test kit, it also requires continual maintenance to ensure the results remain accurate. Membranes and batteries must be replaced and the meter must be calibrated regularly.

But if you want the most accurate measurement possible, You can’t go past a dissolved oxygen meter.

How to increase the oxygen levels in your aquarium

aquarium airstone bubbler with air line tube on black background in water

Well, the first thing you want to do is remove all the contributing factors to oxygen depletion that I mentioned earlier, namely overstocking your tank.

With that out of the way, there is actually a clever trick you can use to increase the amount of oxygen in your tank.

I mentioned earlier how a larger tank exchanges gas more efficiently than a smaller tank due to the larger surface area of the water.

Well, there is actually a way you can “artificially” increase the surface area of your aquarium.

And that method is surface agitation.

To put it simply, water movement on the surface of your aquarium increases its surface area, allowing more oxygen to dissolve and more carbon dioxide to escape.

Any product that helps produce water flow is perfect for agitating the surface of your aquarium, including:

By agitating the surface water in your aquarium, you can potentially stock more fish than you otherwise would have been able to without it.

How to increase oxygen levels in an emergency

So you have just come to discover that panicked fish are gasping for air at the surface of the tank.

There is no time to look for the cause of the problem, you can do that when your fish are safe.

Right now, your priority is saving your fish.

The easiest and quickest way to get oxygen into your aquarium is to immediately perform a large water change – as much as 50%.

The new water will bring with it dissolved oxygen that should keep your fish happy in the short term.

This will buy you some time so that you can hunt for the cause of the depleted oxygen.

Too much oxygen in an aquarium…

A reader actually asked a rather interesting question, one that I thought would make a great addition to this guide…

What happens if there is too much oxygen in an aquarium?

Water can only hold so much oxygen before it reaches saturation.

And once saturation is achieved, no more oxygen is going to dissolve in the water.

Your fish will happily breath in water that is saturated with oxygen – it’s harmless.

But the problem comes when water is supersaturated with oxygen.

And I must stress that this isn’t common in an aquarium environment.[6]

One way that tank water can become oversaturated is from a leaking water pipe or cavitating pumps that increase pressure, resulting in excess oxygen to dissolve in the water.

The other way is through rapid heating of your aquarium. Because cold water can contain more oxygen than warm water, the oxygen gets trapped due to the extremely fast temperature change.

When your fish breaths in the over-oxygenated water, the oxygen leaches out of your fish’s blood stream and forms bubbles in the tissues.

This is known as gas bubble disease and it isn’t pretty…

Fish with gas bubble disease from supersaturated water containing oxygen

Visible bubbles can form in the gills, fins and eyes of the fish. Gas bubbles can also build up in your fish’s heart, leading to death.


It may be invisible, but there is no denying that oxygen plays a hugely important role in your aquarium.

Do you regularly test the oxygen levels in your aquarium? Let me know in the comments below!

Sours: https://fishlab.com/aquarium-oxygen/
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Sours: https://www.ratemyfishtank.com/blog/properly-aerating-your-aquarium
How To Increase Oxygen in a Fish Tank (Fast as well as Long Term)

When it comes to aquariums, oxygen is one of those things that we know we need, but tend to forget about because we can’t see it. That is until there isn’t enough oxygen in our tanks and then we think about it a lot whilst trying to source ways to increase it.

Before we can even consider increasing the oxygen levels in our aquariums, we need to understand where our fish get their oxygen from. Believe me, when I say, it is not from where you would think!

How to increase oxygen in a fish tank? The best way to increase oxygen is to increase the surface area of the aquarium. Increase Surface agitation or water movement on the surface. This allows more oxygen to dissolve and more carbon dioxide to escape. You can also add a source of fresh oxygen by installing an air pump.

how to increase oxygen levels in a fish tank

Where Do Fish Get Oxygen To Breathe From?

The oxygen that your fish breathe is not sourced directly from their water, but rather from the surrounding air. This may sound crazy since water contains oxygen already, but it’s really not.

The hydrogen and the oxygen that make up water are inseparable meaning your fish cannot extract the oxygen to breathe it.

Rather, fish obtain their oxygen from the surface of the water where a process is known as a ‘gas exchange’ takes place. It is known as an exchange because the air and water do a trade swapping CO2 (carbon dioxide) from the water and O2 (oxygen) from the air.

This is a useful and continuous trade since fish breathe in oxygen and give off carbon dioxide.

Fliing an aquarium with water

How To Increase Oxygen In a Fish Tank?

Now we know that the oxygen your fish breathe is introduced into their aquarium, rather than already being present, we can address ways to increase it. There are a number of these, some more obvious than others, but all ones that will help you in your pursuit of more oxygen.

Increasing Aquarium Surface Area – The gas exchange that takes place in order to introduce breathable oxygen into your tank is done on the surface of the water.

This means that the larger the surface area is on your tank, the more oxygen there will be introduced. You should bear this in mind when choosing both aquarium size (water capacity) and aquarium shape (rectangle, cube, bowl) to achieve maximum potential gas exchange.

Increasing Surface Agitation – Surface agitation, or water movement on the surface, increases the surface area. This allows more oxygen to dissolve and more carbon dioxide to escape.

Surface agitation can be achieved in many ways including with:

  • Aquarium bubblers that attach to an air pump via an airline. These come in many shapes and sizes such as air stones which can be placed underneath the gravel, or attached to ornaments such as treasure chests which are pushed open by the pressure releasing streams of bubbles/oxygen.
  • HOB filters which by definition hang on the back of your aquarium releasing filtered water back into the aquarium at the surface. This releasing of water moves the surface creating as previously stated more surface area for gas exchange to take place.
  • Powerheads which are used throughout aquariums to create more water flow.
  • Wavemakers that create waves that are similar to the seas and oceans. They do this by creating a water surge that agitates the surface.
  • Spray bars which sprinkle water gently back into the aquarium from your filter outlet. They do the same job as the water outlet on HOB filters but are made to be used with external filters.
too many fish and they will struggle for oxygen

Stocking Your Tank Correctly – This may sound like a strange way to increase the levels of oxygen in your aquarium but it makes perfect sense when you think about it.

After all, every fish you add to your tank needs oxygen to breathe meaning more fish = more oxygen needed. Overstocked tanks cannot support the oxygen needs of all their inhabitants.

Caring For Your Plants We are always hearing in the fish keeping hobby how plants are excellent for aquariums as they use carbon dioxide and give off oxygen. However, what we don’t hear, is that this is only true if plants are given access to the proper lighting.

Plants, believe it or not, consume oxygen and give off CO2 during the night meaning that extended periods of darkness could deplete your fishes oxygen supply.

However, plants are one of the best ways to naturally increase oxygen into a home aquarium.

Controlling Temperature Rises – Believe it or not, cool water holds more oxygen than warm water does. This means that any rise in aquarium temperatures could lead to less oxygen in your tanks.

To avoid this, you should shade your tanks from direct sunlight, especially on hot days, and consider turning off your aquarium heating as well. If the temperature changes more than a few degrees fans can be used to also lower the aquarium temperature to a more acceptable level.

Taking Care With Chemicals And Medications Certain medications and chemicals, for example, water conditioners, can have a direct effect on the oxygen-carrying ability of the water in your aquarium.

Always read the labels on these products and follow instructions on dose size to ensure that you do not adversely affect your water.

fish tank lighting.

Fish tank emergency

In the event of an emergency, such as your fish are all at the surface gasping for air, the above measures to increase oxygen in your tank will not be sufficient to save your fish.

Rather, you should perform a large water change, up to 50% immediately. This, the adding of new water, will bring in enough dissolved oxygen that your fish will be OK in the short term. You should, however, once the emergency is over source the root cause of the lack of oxygen and address it.

9 Quietest Fish Tank Air Pumps

Too Much Oxygen In A Fish Tank

It would be remiss not to mention that you can over oxygenate an aquarium and that too much oxygen in a fish tank can be bad. So bad, in fact, that it leads to lethal gas bubble disease.

This is where the fish breathes in over-oxygenated water and it leaches out of their bloodstream creating bubbles in their body tissue. It is then visible in the form of bubbles on the gills, eyes, and fins of your fish. Invisibly, it can also build up in the fish’s heart and lead to death.

Conclusion: How to increase oxygen in a fish tank

Over oxygenation happens because water can only hold so much oxygen before it becomes saturated. Once saturated, no more oxygen can be dissolved. Fish will happily, and harmlessly, breath in water that is saturated without any problems.

Problems do arise, however, when the water fish are breathing in becomes supersaturated. This occurrence is not common, but it does happen and is the root cause of gas bubble disease.

If you want to be sure you avoid this disease, simply use a quick, easy, and readily available, from most local fish stores, dissolved oxygen test kit.

The truth is, however, that you don’t really need to be testing your water for oxygen levels unless you think there is a problem.

Having low oxygen levelscan be just as devastating to your fish. Read what signs to look out for and how to correct it quickly before you harm your fish.

There is a much simpler way to ensure your fish get all the oxygen that they need and not too much. Simply follow the guidelines above and use one or two of our oxygen increasing suggestions and you soon have a happily and healthily breathing tank full of fish.

Carl Broadbent

Hi, I'm Carl the owner and editor of Fishkeeping forever. With over 30 years of experience within the industry, I have covered just about every aquarium topic there is and thought it was time to share my knowledge to help grow this wonderful hobby that I love so much. Hope you enjoy my work!

Latest posts by Carl Broadbent (see all)

Categories Aquarium Fish, Fish Keeping Blogs, Start Here!Tags how to increase oxygen in fish tank?, oxygen in a fish tankSours: https://fishkeepingforever.com/how-to-increase-oxygen-in-fish-tank/

Tank oxygenator fish

If you are wondering how to increase oxygen in your fish tank then you are at the right place.

In this article, I am going to show you some ways to increase oxygen in your fish tank in case of an emergency.

I will also share with you some other ways that will help you to solve the low oxygen problem in your fish tank completely.

In case of emergency, you can instantly increase the oxygen level in your aquarium by simply pouring down some aquarium water using a jar from some height.

You can also do a large water change of up to 50% of water to increase oxygen in the fish tank.

Coming to the permanent solution for low oxygen levels includes using an air pump.

The other ways include using a HOB filter or a spray bar.

How to Increase Oxygen in the Fish Tank image

But before that let’s make it clear if your fish tank actually has low oxygen.

How to know if your tank has a low oxygen level?

There are several signs that can help you to know if you are tank has a low oxygen level or not.

Fishes gasping on the surface

The most obvious sign is when the fishes come to the surface of the water and gasping with a wide-open mouth.

Some fish like Betta usually come on the surface to get some oxygen but if you are seeing all the fish coming on the surface or at least some fish coming on the surface more frequently that requires a lot of oxygen then it is a solid sign that your fish tank has low oxygen level.

Fishes moving around less

If you noticed your fishes are moving around less i.e. they are swimming less or swimming slowly than usual then it may be because your aquarium has a low oxygen level.

Fishes eating less

If you noticed all the fishes in your aquarium are eating less food then in this could be a sign that your aquarium has a low oxygen level.

Labored breathing

If you noticed your fishes are breathing rapidly and noticed a more rapid gill movement then this is a strong sign that your aquarium has a low oxygen level.

Now let’s see the causes of low oxygen in your aquarium.

How much oxygen does a fish require?

It really varies from fish to fish but according to FWS 5 parts per million PPM of dissolved Oxygen or higher is a good rule of thumb.

Most of the fishes will start suffocating if the dissolved oxygen level is decreased to 2 PPM or lower.

Ok. So now that we know the sufficient amount of oxygen level in the aquarium tank, you may be wondering if too much oxygen kills a fish in a tank.

Believe it or not but the answer is YES!

As the low level of Oxygen, a high level of Oxygen is also bad for fish.

A very high level of oxygen in the tank causes a lethal gas bubble disease.

In the fish tank having high Oxygen levels, bubbles started formin on the body tissues of the fish.

You can see these bubbles on their gills, eyes, and fins.

If these bubbles start forming in the fish’s heart then it can lead to death.

Now let’s see how you can increase oxygen in your saltwater or freshwater aquarium.

Ways to increase oxygen in your tank in an emergency

Ok so now you know that your aquarium doesn’t have sufficient oxygen for fish.

Your fish is suffocating due to lack of oxygen and they require instant oxygen.

Here I am going to share with you some ways to increase oxygen in your tank instantly.

Pouring water from some height

The simplest way to increase oxygen in your tank instantly is by slowly pouring water into the aquarium from some height.

The steps go like this:

Step 1: Take a clean jar and fill it with water from your aquarium

Step 2: Hold the jar above the aquarium and pour down water from the height.

When you pour down the water from the height it will help to aerate the water and ultimately increase the oxygen level in the aquarium.

Large water change

Another way to increase the oxygen level in the aquarium is to do a large water change (up to 50% of the tank)

The freshwater that you introduced in the tank will have more oxygen that will help to increase the oxygen level in the tank.

Use ice cubes

If the oxygen level in your tank is decreased due to the high water temperature of the tank water then you can cool down the water by putting some ice cubes into a zip-closed bag and then holding that bags into the aquarium.

Use a battery-powered air pump

If the oxygen level in your aquarium is decreased during power cuts then it is wise to get a battery-powered air pump that you can use during a power out-cut to keep the water moving.

Ways to increase oxygen in the fish tank (Permanent solutions)

The ways mentioned above are great in case of emergency but now we are going to look at some permanent solution to cope with the low-level oxygen in your tank.

Use a HOB filter

HOB filters are great to increase the Oxygen level in your aquarium.

They are very small and very easy to use.

The filtered water from the HOB filter will fall down from a height that will help to aerate the water.

Also, the water will go deep into the tank that will distribute the oxygen at the bottom and throughout the tank.

List of the Best HOB Filters for Freshwater Aquariums

List of the Best HOB Filters for Saltwater Aquariums

Use a spray bar

If you are using a canister filter for filtering your aquarium then it may have come with a spray bar. If you are not using it then this is the perfect time to take advantage of it.

If you don’t have a spray bar then I have found a very good sprayer at Amazon.com hereand Amazon.co.uk here.

A spray bar basically helps to distribute the filtered water throughout the surface of the tank that will provide more exposure to the water to aerate, which will ultimately increase the oxygen level in your tank.

List of the Best Canister Filters

Use fountain

If you have a low oxygen level in your pond then using a fountain is a great way to increase the oxygen level in the pond.

Use air pump

Using an air pump is a straight forward way to increase oxygen in your aquarium.

It is meant for it!

An air pump will take air and release it into the aquarium tank through an air stone.

There are a lot of air pumps available for the aquarium but the problem with most of them is that they are not reliable and are a bit noisy.

However, there is an air pump that comes from a reputed brand and doesn’t make noise.

You can check its customer reviews and price at Amazon.com here and Amazon.co.uk here.

ways to increase oxygen in your fish tank infographic

What causes a lack of oxygen in fish tanks?


Overstocking is usually the reason for low oxygen in fish tanks.

It is pretty obvious that if you put a lot of fish in a relatively small aquarium then there will be a shortage of oxygen in the tank that causes low oxygen level in the aquarium.

Elevated water temperature

If the water temperature of your aquarium is high then this could be a reason for a low oxygen level in your aquarium.

Basically, high-temperature water cannot hold as much oxygen as cold water so the rising temperature of your aquarium tank could be a reason for the low oxygen level in your aquarium

Lack of water movement

Lack of water movement also causes low oxygen levels because it is the movement of water that helps to aerate the water in the aquarium.

Low lighting

If your aquarium has live plants then this could be a reason for the low oxygen levels in your aquarium.

Usually, we see advice that plants actually help to oxygenate the aquarium and it is true but if there is not sufficient lighting in the aquarium with live plants then instead of taking Carbon dioxide and releasing Oxygen the plant starts to take Oxygen and release Carbon dioxide that reduces the Oxygen level in the water.

Also if you have Algae in your aquarium then it works the same way as live plants so it also requires a healthy amount of lighting.

Chemicals and medications

If you are using certain chemicals and medications then it may be causing low oxygen levels in your aquarium.

So now that we know the causes of low oxygen in your aquarium.

It makes sense to know how much oxygen does a fish actually require.

Causes of low oxygen in a fish tank infographic


So as you can see there are different ways to increase oxygen in the fish tank.

If you are in an emergency then simply pouring the aquarium water with a jar from some height can help to increase oxygen in the tank or performing a large water change can help to increase oxygen in the tank.

If oxygen levels are decreased in the fish tank due to high water temperature then keeping some ice cubes in a zip-closed bag inside the aquarium will cool down the water and help to increase oxygen in the aquarium.

If you are facing the problem of low oxygen level during power out-cuts then using a battery-powered air pump will oxygenated water during power out-cuts.

The permanent solution for the decreased oxygen level in the fish tank includes using a HOB filter or a spray bar or air pump.

If you want to increase oxygen in your pond then using a fountain is a great way to oxygenate the pond water.


How do you oxygenate a fish tank?

There are several ways to oxygenate a fish tank. The simplest way is to use an air pump if you are not using it.
In case of an emergency, you can do the following things to increase oxygen in the fish tank:
1. Pour down the aquarium water from some height into the aquarium
2. Do a large water change (up to 50%) of the tank
3. Use ice cubes

For the permanent solution for low oxygen issue, you can do the following things:
1. Use HOB filter
2. Use a spray bar
3. Use an air pump

If you are facing low oxygen issues during power cuts then you can use a battery-powered air pump to cope with the problem.
In case you want to increase oxygen in your pond using a fountain is a great way to oxygenate pond.

Can you have too much oxygen in a fish tank?

Yes, you can have too much oxygen in a fish tank and it is harmful to your fish. It causes lethal gas bubble disease.

Do filters add oxygen in fish tanks?

Filters like HOB filters can add oxygen in the fish tank. The filtered water coming out from the HOB filter gets exposed to air before falling into the tank which helps to oxygenate the water.

How can I oxygenate my fish tank without electricity?

There are a couple of ways to oxygenate a fish tank without electricity.
The first way is simply pouring down the water of your aquarium using a jar or pitcher from some height it into the aquarium. This way the water will get exposed to the air which will oxygenate it.
The another way to oxygenate the fish tank is by performing a large water change (up to 50%) of the tank water.
The newly introduced water will have more Oxygen, this way you can cope with the low oxygen level problem in your tank.

Can you turn off a fish tank pump at night?

If you have an air pump which is separate from the main filtration system of your aquarium then it should not cause any problem if you turn it off during the night.

Why are my fish at the top of the tank gasping for air?

When your fish comes on the top gasping for air it is a strong sign that the aquarium does not have a sufficient amount of oxygen.
As the surface of the water has the highest dissolved oxygen fish come to the surface to take oxygen.

How long can a fish live without oxygen?

A fish can live up to 2 days without oxygen.

Are bubbles good for a fish tank?

Air bubbles help to oxygenate the fish tank. The air bubbles also introduce carbon dioxide in the fish tank that is good for the plants in the aquarium.
The plants take carbon dioxide and produce oxygen for the fish.
Air bubbles also keep the water moving in the fish tank so it reduces the growth of the algae.

Why do fish go to the top of the tank?

When there is a lack of oxygen in the tank fish usually go on the surface to take oxygen because the surface has the highest amount of dissolved oxygen.

Sours: https://aquagoodness.com/how-to-increase-oxygen-in-fish-tank/
Are Aquarium Air Pumps Oxygen Tanks? Fish Tank Bubbles, Do You Need Them?

Aquarium Aeration and Oxygenation | Tropical Fish Hobbyist Magazine

Author: Laura Muha

The Skeptical Fishkeeper: December 2007

A few weeks ago, I noticed that the airstone in my 20-gallon tank was starting to fizzle. Instead of perking away merrily, as it had when I’d added it to the tank some months before, it was emitting a feeble stream of bubbles, almost like a carbonated soda that’s been left too long in the sun.

No big surprise there; airstones—whether wood, ceramic, or actual stone—are full of pores that over time tend to get clogged with mineral deposits and algae. And while I’ve heard of people recycling them through a multi-step process that includes boiling them in vinegar and water, scrubbing them, and forcing air back through them, my feeling about that is: why bother? When compared to the many other things that need periodic replacement in aquaria, a 50-cent airstone is hardly a big deal.

However, you know me (or at least you do if you read this column regularly), and I like to ask questions; and if I can get a column out of it, all the better. Therefore, I present to you the topic of the month: airstones and other forms of added aeration. Are they really necessary?

How Fish Breathe

To find out if airstones and added aeration are really necessary, let’s start with the basics. Fish, like humans, need oxygen to fuel their metabolic processes, and like us, they will die if deprived of it for long. However, the similarities end there, because, at the risk of stating the obvious, fish live in a very different environment than we do.

Even under the best circumstances, there’s 95 percent less oxygen in water than there is in air. Plus, water is 800 times more dense than air and 50 times more viscous. So, fish have to expend a lot more energy “breathing” water—that is, pumping it through their gills—than we do breathing air.

The structure of a fish’s gills, however, helps to make up for this because the feather-like filaments and lamellae create a vast surface area that enables the fish to extract about 80 percent of the oxygen from the water that passes over them. By comparison, our lungs extract a paltry 25 percent of the oxygen contained in every breath we take—and that’s only if we’re in peak condition.

However, we do have one thing going for us that fish don’t have, in that the level of oxygen in our atmosphere remains a relatively constant 21 percent. So barring an oxygen-consuming disaster such as a fire, we can count on plenty of it being available to us every time we inhale. Fish can’t count on the same, because they live in an environment in which the amount of available oxygen can vary, sometimes considerably, from one moment to the next depending on things like barometric pressure, salinity, the presence (or lack thereof) of plants, the weather, the depth of the water, the time of day, and especially temperature. But I’ve always found that concept to be a little confusing; I mean, aren’t water molecules themselves 1/3 oxygen?

Oxygen In Water, Explained

In search of an explanation, I called my favorite chemist, who also happens to be my father, Dr. George Muha, a professor emeritus of chemistry at Rutgers University.

He explained that while water itself is composed of two hydrogen atoms and one oxygen atom, the oxygen in the water molecule itself is not the oxygen the fish are breathing. That’s because—here I could almost hear him thinking “Duh!”—the oxygen in water molecules is already tied up making, well, water. Instead, the oxygen that fish are breathing is essentially the same atmospheric oxygen we humans breathe; it’s just that when it comes into contact with water, it dissolves into it in much the same way that, say, sugar does.

Sometimes, this contact point occurs beneath the surface. Aquatic plants, for instance, release oxygen during photosynthesis, although this happens only when the sun is out. (At night and on cloudy days, they pull oxygen from the water instead, thus explaining why oxygen levels can drop overnight or in bad weather.) And if you have an airstone, an air-driven box filter, or some kind of decorative bubble device in your tank, the bubbles it produces are pumping some oxygen into the water as well.

How Tank Dimensions Affect Oxygen Levels

By far the largest amount of oxygen present in most tank water has worked its way down from the surface, which is one of the reasons that a wide, shallow tank is a better choice for most fish than a tall, narrow one.

Compare, for instance, a 20-gallon long tank with a 20-gallon regular. Both hold exactly the same amount of water, but their dimensions are different: the regular is 24 inches in length, while the long is 30 inches in length; both are 12 inches wide.

If you multiply the length by the width to get the surface area of each, you’ll see that the 20 long has a much bigger portal through which oxygen can enter the water than the 20 regular: 360 square inches vs. 288.

And the long tank has another thing going for it as well. It’s shallower than a 20 regular (12 inches deep versus 16). So oxygen entering the tank at the surface will work its way to the bottom of a 20 long faster than it will a regular 20, if all other things are equal.

However, all things are not always equal when comparing oxygen levels of various tanks, because of all the other variables that come into play. Salt water, for instance, doesn’t hold as much oxygen as fresh water, and the same is true of warm water when compared to cool.

That’s because water molecules become increasingly agitated as the temperature rises, and the more they bounce around, the harder it is for gases to dissolve in them and the easier it is for the oxygen that’s in there to get bounced out.

What Happens When Oxygen Levels Drop

Other substances that aquarists sometimes add to water (medications, for instance) also can cause oxygen levels to drop. That’s because some such substances bond so tightly to water molecules that—to grossly oversimplify an incredibly complicated dynamic—it effectively decreases the amount of water in solution that’s available to hold the oxygen.

When this happens, fish have a number of ways to compensate. They can push water through their gills faster (the fish equivalent of panting); they also tend to hover near the surface where the oxygen content is higher. Over the long-term, they can increase the number of red blood cells and the concentration of hemoglobin within them to more efficiently transport oxygen to their tissues.

And in truly desperate situations, they may do what’s known as piping—swimming head up at the surface, opening and closing their mouths as they suck at the oxygen-rich skin of the water, something I witnessed the first summer I kept goldfish.

An Anecdote About Overstocking

Back when I wasn’t experienced enough to understand stocking limits, I put too many goldfish in a too-small pond. When I went outside to feed them one morning I found them all hanging at the surface opening and closing their mouths as if they were gasping. A frantic call to the pond shop identified the likely problem. It was very hot, so the water wasn’t holding much oxygen to begin with; it also was overcast, so the plants in the pond were probably competing with the fish for what was available (and so were the nitrifying bacteria), and the pond was stocked to capacity so there was no margin for error. The oxygen in the water was getting used up faster than it could be replenished, and the fish were desperate.

The temporary solution was to agitate the surface of the water to get oxygen into it faster, in much the same way that you’d stir your coffee if you wanted to get the sugar to dissolve more quickly. While my husband rushed out to get a submersible pump with a fountain head while I created some temporary agitation by spraying the surface with water from the hose. The results were remarkable: Within seconds, the fish stopped gasping and began to swim normally (although they still stayed close to the surface).

After we installed the fountain, we never had another problem. However, having learned a few things since then, I now keep fewer fish in a much bigger pond equipped with both waterfall and fountain.

How Much Oxygen Do Fish Need?

All of this leads to an obvious question: What’s the critical oxygen level for fish? But once again, there’s no easy answer. Goldfish, for instance, are very efficient at getting oxygen to their tissues, so they’re able to withstand low oxygen conditions for longer than some other species. So can gouramis, which evolved in the low-oxygen conditions of shallow, stagnant ponds in Southeast Asia and have what is known as a labyrinth organ. This is a sort of primitive lung that allows them to breathe surface air when they can’t get enough from the water.

Generally speaking, however, large fish use more oxygen per hour than smaller fish, and faster-swimming fish use more oxygen than slower swimmers, while fry often need more oxygen than adult fish. A fish’s consumption of oxygen also increases after feeding—some studies have found it to be by as much as 50 percent—because of the energy demands of digestion and growth.

However, the picture is further complicated by the fact that fish are cold blooded, so the speed of their metabolism corresponds to the temperature of the water they’re swimming around in. The problem is that the warmer the water gets, the more active the fish become, and the more oxygen they need to fuel their increased activity (their demand can double or triple with every 10-degree increase in temperature), but warm water also holds less oxygen.

The Basics of Aeration Devices

There are a number of ways to help counter this, and that’s where aeration devices come in. There are two basic types: Those that infuse oxygen directly into the water (such as airstones and decorative bubble walls) and—even more effective—those that expand the surface area of the water to give the oxygen more entry points. That’s what I was doing when I sprayed my pond with the hose, for instance, because each droplet of water picked up a lot of oxygen as it cascaded through the air; that’s also part of the point of waterfalls and fountains. And in aquariums, certain types of filters help aerate the water as well. These include hang-on-back filters and trickle filters.

Some fish farms involved in high-intensity aquaculture sometimes use such means to hyperoxygenate the water, which allows them to increase stocking levels without increasing the amount of water in their systems. However, there are some indications that this can stress fish; in one paper reported at a World Aquaculture Society meeting in 2006, Swedish researchers found higher levels of the stress hormone cortisol in Atlantic salmon that had been raised in hyperoxygenated water.

Too much oxygen in water can lead to the potentially lethal gas bubble disease, in which gas comes out of solution inside the fish, creating bubbles in its skin and around its eyes. (Excess nitrogen, however, is a far more common cause of this disease.)

Are Airstones Necessary?

All of this brings us back to the humble airstone and the question I asked at the outset of this column: Is it necessary?

Probably not, if by “necessary” you mean that your fish would die without it. (If that’s the case, you’re way overstocked.) Yes, it adds oxygen to the water, but if that’s what you’re worried about, there are more effective ways to do it—with a trickle filter, for instance.

On the other hand, can airstones and other bubblers serve a useful purpose? Yes, within limits. They do add some oxygen to the water, and the bubbles they create help to keep water moving within the tank; by strategically locating it in areas in which water circulation might be less—near the bottom, for instance—you’ll help to keep suspended particles circulating so that they can be sucked out of the water by the filter.

So while I’m not going to bolt out to the pet shop to replace mine the way I would if, say, my filter quit working, I’ll probably pick one up eventually. Because when it comes to aeration, every little bit helps.

See the full article on TFH Digital http://www.tfhdigital.com/tfh/200712/#pg56

Sours: https://www.tfhmagazine.com/articles/aquarium-basics/aeration-and-oxygenation

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Insufficient Oxygen in Aquarium Water

Low oxygen levels are rarely a problem if an aquarium is well maintained and not overstocked. However, if fish are gasping at the surface of the water, that should set off a red flag prompting further investigation. Here is what to look for and how to remedy the problem of low oxygen.

Symptoms of Low Oxygen

Unfortunately, there is no flashing light or blaring alarm that goes off when dissolved oxygen levels drop too low in an aquarium. Aside from actually testing the water for dissolved oxygen, the only indication of trouble will be the behavior of your fish.

Fish will initially react to lower oxygen levels by simply moving around less. They will swim less vigorously and even eat less often. As oxygen levels drop further, the fish will begin to show labored breathing and more rapid gill movements as they desperately attempt to get enough oxygen from the water by passing more water over their gills.

Eventually, fish will begin gasping at the surface of the water. This surface breathing should not be confused with fish feeding at the surface or fish that can normally take in some air at the surface, such as labyrinth fish. Certain species of fish, such as bettas, gouramis, and Corydoras catfish will periodically take a leisurely gulp of air from the surface. This is perfectly normal behavior for them, and these fish will not remain on the surface taking breath after breath. When any fish do go to the surface of the water for oxygen, they will gasp repeatedly, often with a wide-open mouth, sucking in the surface layer of water, which holds more oxygen.

Emergency Steps

If all of the fish are gasping at the top, the problem is critical and swift action should be taken. But action should be taken even in cases where only one single fish is gasping at the surface because eventually, the problem will get worse. Those that aren’t gasping for air are probably stronger fish or those that require less oxygen. If left unattended, eventually they too will be severely weakened by low oxygen levels.

The initial action to take is to perform a large water change of as much as 50 percent. At the same time, increase the water movement by temporarily adding a powerhead, airstones, or even an additional filter. The newly agitated water will introduce more oxygen to the aquarium, while the increased water movement will improve the oxygen exchange, buying some time to address the underlying cause. Next, the additional corrective steps will depend on the root cause of the low oxygen level, which should be determined promptly to assure the problem is permanently corrected.

Causes of Low Oxygen

Overcrowding is the number one reason for low oxygen in an aquarium. In fact, other oxygen-depleting factors rarely cause fatalities by themselves if the aquarium is not also overstocked. That’s not to say that the other factors can be ignored, but if the aquarium remains overstocked, correcting the other factors will not fully resolve the issue. Causes of low oxygen include:

  • Overcrowding
  • Elevated water temperature
  • Lack of water movement
  • Excess waste accumulation
  • Low lighting with live plants
  • Use of certain chemicals

High Water Temperature

Higher temperature water cannot hold as much oxygen as can water at colder temperatures. Performing a water change with lower temperature water will help to introduce fresh oxygen. A partial water change with dechlorinated water in the 65-70 degree F range will be safe for most tropical fish and help lower the aquarium water temperature. If the aquarium water becomes overheated, the heaters should be turned off, as well as lights. Remove the aquarium cover. Blowing air across the surface from a fan will also help to cool the water; it is wise to place a piece of screen over the top to keep fish from jumping out. Additionally, a few ice cubes placed in a zip-close bag can be placed in the tank to help drop the water temperature. Be sure not to lower the temperature below the fishes' normal temperature range.

Water Movement

Stagnant water will have lower oxygen levels. This is particularly true lower in the water column, where no oxygen exchange is occurring. Water at the surface will have more oxygen, but because it’s not circulating sufficiently, that oxygen doesn’t reach the lower portion of the tank. It is important with water circulation to move the water at the bottom of the aquarium to the top, which displaces the aerated surface water down into the tank.

Filters go a long way toward increasing oxygen in the water, as they cause water movement at the surface where oxygen exchange occurs. Filters should take in water at the bottom of the tank, and release it back into the aquarium at the surface, thus distributing oxygenated water throughout. Make sure your current filter is operating at full capacity. Often, the underlying problem is simply a badly clogged filter that is no longer moving much, if any, water through it. All that is needed in such cases is a good filter cleaning.

More water movement always increases oxygenation. Add an additional filter or replace the existing filter with a higher capacity unit, if necessary. Other options are using a powerhead, putting a spray bar on the outlet of the filter, or using airstones. In a pond, the addition of a fountain will do wonders for aerating the water. Anything that moves the water at the surface, or splashes it through the air will increase oxygenation as well. In a pond, the water circulation needs to move all the water throughout the pond from bottom to top, to avoid low oxygen areas of stagnant water.

Excess Waste

Another common cause of low oxygen is often found in conjunction with overstocking. The more fish you have, the more waste they produce! Excess waste, clogged filters, and algae overgrowth all can cause decreased dissolved oxygen as well as a lowered oxygen-carrying capacity in the aquarium. Breakdown of detritus and waste by the bacteria in the aquarium gravel uses a large amount of dissolved oxygen. A thorough tank cleaning that removes debris from the gravel will turn that around, and good ongoing maintenance will help prevent the problem from reoccurring.

Live Plants

Although it is not a common occurrence, live plants can be a cause of low oxygen in an aquarium. When they are exposed to light, all plants use carbon dioxide (CO2) and give off oxygen (O2). But when the tank or pond is dark the process reverses, and all plants including all algae will consume oxygen. If the aquarium has reduced or no light for a lengthy period, the plants or algae in the system could deplete enough of the oxygen to cause the fish to be affected. The obvious solution is to increase the lighting.


Some chemicals used to treat disease or modify water parameters can also impact the oxygen-carrying capacity of the water. Whenever using a chemical additive, always read product literature to ensure it doesn’t lower oxygen-carrying capacity. Always increase water circulation when medicating the fish. When troubleshooting an oxygen problem, discontinue the use of any chemicals that are not absolutely needed.​

Sours: https://www.thesprucepets.com/low-oxygen-in-aquarium-water-1381215

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