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Degassing Oxygen from Hydrogen Peroxide                           

I dare say, we’ve all been in a situation where we wished we could increase the O2 levels in a tank. Aside from aeration and lowering temperatures, water changes et al, it’s not all that easy.

Testing for O2 is easy:

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But raising O2 is more difficult. And chances are, if you suspect your fish need oxygen, they probably need oxygen.  And extra oxygen can help ailing creatures through unrelated difficulties.

One partially successful, but very dangerous method is to add common peroxide as it breaks down into water and O2. Hydrogen peroxide toxicity is dangerous and easily overdosed.  

In fact, it is this very toxicity that prevents you from being able to use all of the available O2 in peroxide.

The maximum amount of O2 available by dosing peroxide directly into the tank is only 1% of the total free O2 available in peroxide!

Not unlike degassing Chlorine from tap water, you can degass pure Oxygen from peroxide without risk. The method below will release nearly 100% of the O2 without any toxicity at all.

This may present a quick and inexpensive way to temporarily but dramatically increase the oxygen level of a fish tank with 0% chance of toxicity. All one needs is about $10 worth of common hydrogen peroxide, a 5-gallon bucket and a small air pump and stone. 

The amount of common peroxide (3%), the size of the bucket, and the output of the air pump are married to the following numbers. That is, using these amounts and sizes will produce the amount of O2 specified below. If you need more or less, you simply scale it up or down.

You'll need:

A typical drug store bottle or hydrogen peroxide, 32 oz is about 0.89c or thereabouts. You'll need 10, 32oz bottles of 3% Hydrogen Peroxide.


An aquarium air pump that outputs approximately 0.5 liters/hour.




A 5-gallon Lowes bucket. BTW I say ‘Lowes buckets’ because Home Depot buckets are not airtight, at least not with the default lid, and HD buckets are orange, allowing light through them which breaks down H2O2. Lowes are dark blue but whatever you use, if it's dark, closes and holds 5 gallons, it'll work.


Make a hole just large enough for an airline tube in the bucket top. If using a wall powered pump, make one for the power cord as well. Seal around both holes to make it as airtight as possible (I use hot glue). I hung the pump from its cord and tied a knot in the power cord to hold the pump up above the peroxide in the bucket. I’ve opened it to show how simple it is:


Add the 10, 32oz bottles of peroxide and close it tightly. Press the top back on and try to make certain it's fully closed. Simply start the air pump for 48 hours of augmented O2. Replace the 10 bottles of H2O2 every 3rd day to resume the same operation and values.

This informal rig will output approximately 80% pure O2 for 24 hours, dropping to about 40% pure O2 for the next 24 hours. Finally dropping to circa 25% for the next 24 hours which isn't much different than normal air (normal air is about 21% oxygen). So, it's really an effective O2 generator for the first 48 hours.

After 48 hours, you basically have a half-filled bucket of distilled water. ONLY pure oxygen goes into the tank and nearly 100% of the O2 that is available in H2O2, or about 94% greater amounts of O2 than would be possible by adding H2O2 directly to the water.

The way it works is the H2O2 has a half-life of 24 hours. 2.5 gallons of 3% peroxide has about 6 gallons by volume of available O2 in it. If the lid is closed, it's enough positive pressure applied to prevent significant oxygen loss. However, once you turn on the air pump, the internal pressure in the bucket goes negative and the H2O2 begins to leach pure O2, leaving behind H2O.

The rate of flow of the air pump must be <= than the rate H2O2 releases O2 such that the air pump output should be between 0.3LPM-1LPM or ideally around 0.5 liters/minute.

At that rate, the air pump output essentially matches the rate H2O2 leaches O2 so the air pump output will begin outputting 100% pure O2 at Hour-1 but drops to 50% O2 at Hour-24, or a 75% O2 average on Day-1. Day-2 will see the half-life erosion again reducing the O2 from now 50%, to 25% in the next 24-hour period, averaging 37.5% O2 for the second 24 hours.

Alternatively, and more potently, you may administer pure O2 with devices like these which of course are more effective and precise at cost of $300:         

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Lastly, I always try to use commonly available items or techniques as in this way, it’s approachable and easily employed as opposed to equipment only a lab may have access to. To that end, you can buy MUCH stronger peroxide in hardware stores. Some 70% vs 3%! If you choose to, that goes much further than 3% bottles from a drug store. Just scale it down by dilution if you use industrial peroxide. It’s very dangerous to handle but it would reduce the operational cost of this no frills “O2 generator” to pennies. But be careful, industrial peroxide is caustic!




Edited by dasaltemelosguy
Needed to be more concise and images reduced.
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