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Re: H2O2 question

> From: Bob Ashcraft <bashcraft at brashearlp_com>
> Subject: H2O2 question
> I just read on another list, where a person reported, that he adds H2O2 to a tank of fish to
> provide additional oxygen during power failures.  His recommended dosage is 1/2 to 1 cup H2O2
> per 100 gallons.
> Two questions, first, (since I'm not a chemist) can H202 break down into just water and oxygen?

	Yes.  It's pretty slow unless catalysed.  The Fe3+ ion will do that, as
will other things.

> and if so, when added to an aquarium, does it need something to start the reaction, or does it
> happen on it's own over time?

	The problem is that it is quite likely simply to attack organic
material in the tank (fish, plants, bacteria, algae) rather than release 
much oxygen.  That is why it is used as an antiseptic.  The dosage above,
which I will assume means 250 mL of 3% H2O2 in 100 U.S. gallons, would
produce about 9 ppm oxygen in the water if it all decomposed immediately
to water and oxygen.

Paul Sears        Ottawa, Canada