Hydrogen Peroxide and Its Utility

[Crepe]

Hello everyone! As some of you might know, I'm a chem freak. I just love all things biochemical. And today I felt that I should, as a small public service announcement provide a little information about the versatility of H2O2 in aquaria.

Overview
Hydrogen Peroxide (H2O2) is a very strong oxidizing compound that is often used as an oral and external antiseptic wash in lower concentrations: 3-5% by mass. H2O2s oxidizing properties are also used in hair bleaching. It also has a strong tendency to break apart into O2 gas and liquid water, H2O, in elevated temperatures and simply over time.

As we all know, oxygen is extremely reactive. It oxidizes. The origin of the term oxidation, or in technical terms, the stripping of electrons from another substance, comes from oxygen's ability to do just that. This ability to oxidize allows it to react potently with many compounds organic and inorganic.

I use 3% H2O2, available at any drugstore. The mention of H2O2 in this short little "article" refers to 3% concentration H2O2.

The applications:
Most of us have experienced the effects of H2O2 in scrapes and wounds, the fizzing, the sting. It is for this very effect that H2O2 lends itself to be such a wonderful item in the aquarium. The fizzing you see is actually a reaction been the H2O2 and an enzyme your body produces, catalase. The catalase reacts with the H2O2 to break it into two safe components: H2O and O2. The reason our bodies react to H2O2 in such a way is because of H2O2's oxidizing properties. Upon contact with cells, H2O2 rapidly oxidizes them, causing them die and in some causes "explode" or go through cell lysis. When these cells explode and break down they release the enzyme Catalase to stop this reaction. Simpler organisms such as algae, bacteria, and various protozoans and parasites cannot produce catalase or cannot produce a substantial amount of catalase to counteract the oxidizing effects of H2O2.

Algae removal with H2O2 is simple. One can either dose the tank fully with H2O2 at a ratio of 1-2mLH2O2/4L of water. Thus say for a 80L tank, I would dose a maximum of 160mL or a minimum effective amount of 80mL. This form of treatment however is substandard and may only weaken the algae, not kill it. A more effect method is to fill a cup with a tank's entire dosage amount and use a plastic syringe, turkey baster, pipette or related device to directly dose H2O2 on the algae itself. However, doing this requires turning all water movement off in order to maximize contact time.

Hydrogen Peroxide can also be used as an algae removing bath. However, I don't advise this treatment as there are more effective alternatives such as bleach. The one benefit of H2O2 is its safety around the aquarium. You don't need to do a dechlorinating rinse after an H2O2 bath. You can actually dip the plants for a minute or two in 3% H2O2 straight up. This however WILL kill nonvascular plants such as Moss and delicate plants along with algae.

Another use for H2O2 is in the treating of sores and wounds in fish. Yes I know, you heard me, wounds. As some of you know I am a ponder and keep several large koi. Occasionally they get hurt, parasites etc. and get open sores on their bodies. When this happens I generally spot treat with straight up H2O2.
You can treat smaller fish by:
1. Netting the fish
2. In the wet net hold the fish such that it cannot flop around and the wounded side is facing up.
3. Using a pippete or dropper spray a stream of H2O2 into the wound to clear it of both debris and infection. This treatment should be coupled with an all around antibacterial as well.
EDIT: Avoid using this on extremely small fish [under 4 inches]. One would only have to imagine the gill damage if any of this got in there. Also avoid using this on extremely injured fish, this will only irritate the fish more and cause more harm than good.

The final, less known, use of H2O2 is in the generation of Oxygen for transporting fish. Every 2mL of 3% H2O2 you add to a litre of water will increase the oxygen levels of the water in the bag by .15mg. I wouldn't add anymore than 5ml or a teaspoon of this stuff into any transport bag though. As you have probably figured out already, this stuff although harmless in small amounts, in gratuitous concentration will oxidize ANYTHING living, including fish and especially invertebrates.
Another way of providing O2 with H2O2 is a bit more grotesque. Begin with a half cup or third cup of H2O2 and a hunk of beef liver. Mash or blend the liver to paste (like patte for all you foodies) and add it to an empty transport bag. Add the H2O2. The liver contains a massive amount of catalase. In essence you have yourself a DIY O2 generator. This reaction however goes away after a few minutes, but it will be enough to fill at least one bag with O2. You can vent the O2 being generated with airline tubing held in place with tight rubber bands into another transport bag that will hold fish.

And that's about it!
Remember H2O2 is a oxidizing chemical. Use with discretion as always.

Sources:
http://www.fao.org/docrep/009/af000e/AF000E06.htm
http://www.ag.auburn.edu/fish/intern.../transport.htm
http://www.aquarticles.com/articles/..._Peroxide.html