I first heard of adding H2O2 to water years ago, as an emergency fix when fish were suffocating from crowded conditions during shipping. I've seen it added to overheated ponds to buy time until pumps were repaired.
It works, but it was an emergency solution, not a "treatment." The important part was addressing the issue that caused the problem in the first place.


I've tried a peroxide dip for algae, with mixed results leaning to negative. I was experimenting with zoas, which I knew was risky. The algae died quickly, but so did all inverts, macro, and sponge. Some zoas recovered, some didn't. The ones that had algae growing around them survived, the ones that had algae growing on them did not.

Maybe my concentration was too high. I thought I had it right, but maybe I was mistaken. Or maybe it's not as safe for inverts and sponge as some sites have claimed. Either way, I'm sure glad I didn't make the mistake of doing it in the main tank.


If someone were to experiment with it in their main tank, I'd love to see pics/video. The viscosity of H2O is very similar to that of the H2O2 solution. How can you tell where it will end up when you squirt it at something, when the high currents are taking it everywhere and anywhere?

My favorite part of my tank is all the microfauna. If you were to spray H2O2 at a stationary coral, are all the sponge and tiny critters near it going to suffer?