How to Add Oxygen to a Fish Tank?

Oxygen is essential for fish survival. When oxygen supply is not enough, the fish can have low appetite, swim less vigorously and have labored breathing shown by the rapid movement of gills If you see your fish going to the surface and gasping repeatedly with its mouth open wide, it is a sign that oxygen supply is insufficient.

Besides fish needing oxygen supply, other living things in the aquarium also need it. Beneficial bacteria need oxygen to break down waste. The plants that grow there also need oxygen. Basically, everything that lives and eventually decays or dies off in your aquarium requires oxygen, and therefore depletes it in the process of consumption.

The two ways that oxygen get into your aquarium water via gas exchange are water movement and plant photosynthesis, and the maximum amount of oxygen that can be saturated or dissolved depends on the temperature of the water and its salinity.

If you’re having trouble with low oxygen in your tank, here’s how to remedy the problem:

  • Increase surface area – the larger the area of the water surface is, the higher is the ability of the tank to absorb oxygen
  • Surface agitation – increases oxygen and allows carbon dioxide to escape; use an air pump for this purpose
  • Control temperature – cool water holds more oxygen than one that has a higher temperature


Signs Your Tank Has Low Oxygen

A change in the behavior of your fish will tell you there’s something wrong with the aquarium set-up. Of course, besides oxygen levels, there are other problems that might ensue from improper maintenance, such as:

  • White cloudy water – caused by bacterial gloom, washed gravel, or dissolved constituents
  • Dead fish – not only oxygen level to check; you also check:
    • Water acidity – pH level
    • Dirty filter
    • Disease
    • Food
    • Temperature level
  • Green Water and Worms – caused by buildup of organic waste due to overfeeding

In case there is less oxygen supply, fish have a couple of ways to compensate. They will try to push water through their gills faster. This is what you call “panting”.

Next thing you will notice is they will hover more at the surface, since that is where oxygen level is higher. If the problem persists for a long time, the fish compensates by increasing the number of their red blood cells and the hemoglobin concentration in their blood. This is for a more efficient transport of oxygen to their tissues and cells.

In a truly desperate situation where oxygen supply deficiency is too much for them to bear, what the fish will do is what is known as piping – that is, they will swim head up to the surface and suck at the oxygen-rich skin of the water.

It is also important that you understand stocking limits for keeping fish in aquarium tanks. A crowded tank can easily turn the environment’s temperature higher.

Manual Addition of Oxygen to Fish Tank

You can manually add oxygen to your tank, which is especially useful during a power outage and the air pump in your aquarium is not battery operated. Providing oxygen manually is also a good way to keep the water circulating.

Do the following:

Pour water from above

Take a cup or any container that can hold water. With it, scoop water from the aquarium. Then hold it up a good distance from the aquarium. Next, pour the water back into the aquarium. Repeat this process several times.

The idea is that as the water drops, it will gather oxygen along the way and the oxygen gathered will be incorporated into the water in the aquarium.

How many times and how often you will do this on a single occasion will depend on how long will the added oxygen last for your fish’s consumption. Once they start swimming for the surface again, perhaps it’s time to agitate the water another time as well as do the cup method again.

Use an aquarium bubbler or an air stone

A bubbler releases bubbles to the aquarium, and in this process, it helps oxygenate water when the bubbles pop on the surface. Besides the added oxygen, a bubbler brings other benefits such as:

  • Keeping water from becoming stagnant or toxic to your fish
  • For decorative purpose – think of bubble curtains or walls streaming behind your fish, and also bubbles emanating from a position near the treasure chest or a clam shell
  • Soothing sound – play that familiar fountain or rushing stream sound you remember in your young days; that’s the sound you can achieve with the use of an air stone.

Use filters

For added surface agitation, you may opt for using a HOB (hang on back) filter. Quite a number of these filters have outputs that drop water, with the process and generated results much like the cup method previously mentioned.

Water circulation is another benefit of this method. The trick is to move water from the lower part of the aquarium to the upper part so that that portion of the water also collects oxygen from the air.

Powerheads for large tanks

Experience would tell us that there are limits to the results when it comes to the use of filter or air stones, thus they are not the best solutions for large tanks holding large amounts of water.

For this requirement, the one recommended is a powerhead. An aquarium powerhead is usually used to create flow throughout a fish tank.

If you would just like to imitate a laminar river current, a single powerhead is enough for that purpose. Place it at the one end of the aquarium.

For requirements that seek to create more turbulent flows within the tank, position multiple powerheads in different parts of the tank.

Bottom line:

If you just need to increase oxygen supply a bit, surface agitation techniques and tools will suffice for the purpose. However, if there is a need for overall aeration where there is no dead spot within the entire setup, a powerhead may be the best option.

How to Set Up an Air Pump

Fish keeping hobbyists have different experiences setting up an aquarium air pump and that goes too with choosing fish and buying accessories. In the matter of setting up an air pump, these are the usual steps to take.

  • The first step is to buy it, and usually, the shop owner will ask if the customer wants an airline tubing and how long is needed. If you plan to use an air stone connected to the air pump, you will have to purchase an airline tubing. Tubing that comes in milky are of superior quality and will not easily stiffen over a long period of use.
  • Once you brought the pump home, look for a safe place to hang it vertically using a strong wire. This wire should be placed running through the hole that’s provided by the manufacturer of the air pump.
  • Safe place means to hang the air pump above the aquarium. That is to keep water from the aquarium from flowing back into the tubing. Also, hand the pump free standing (meaning, without touching any surface) as it will vibrate if it does touch a surface and make a lot of annoying noise.
  • Finally, connect the pump to the power outlet and switch it on. If the bubbles produced by the air stone cause too much water agitation and if it is already causing the water to spill over, switch the pump and consider fixing the problem with the use of a T valve or a suction cup.

Alternative Options to Add Oxygen to Fish Tank

Prior to considering specific methods, it is necessary to address the issue of surface area first. The surface of the water is that part that is in contact with air at any given moment.

This is particularly an important idea to consider when deciding on the shape of the tank that you will use. Standard tanks have widths that are greater than their lengths. However, some tanks have taller walls than others.

You may think that a tall tank may be a good choice for providing room for quite a number of fish, but that may not be a good decision at all, since, for example, a 15-gallon standard actually has a bigger surface than another 15-gallon tank that is taller.

After considering the dimensions, you can proceed to deciding whether to use an air pump, a powerhead, or you will add air stones and filters. Make sure though that you don’t over-oxygenate because that is also a perilous condition for your fish.

Here are additional aeration ideas:

  • Ornaments: Look for décor pieces that also function as an aeration device, much like an air stone. A pirate ship would be a nice ornament to grace your aquarium while it moves back and forth, while producing bubbles for your fish and aquarium.
  • From Container: Expose water to pure oxygen gas from a close container. You may also bubble oxygen through the water. This method is particularly useful when the fish need to be transported.

Remember not to supersaturate your tank with oxygen as this is also detrimental to your fish’s health and may even lead to their death.

Lastly, in adding oxygen to a fish tank, it is very important that you consider various factors, such as fish stock and the number of elements inside the tank that may cause too much denseness or crowdedness, the size of the tank, and the method to use to augment oxygen supply.

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