what effect does peroxide have on animal inhabitants, other than supplying o2?
I used better than 4ml/gal one day after using 3.??ml/gal and killed 99% of the snail population. The fish seem fine, except a couple zebra danios have nipped-looking fins, though they nip at each other regularly, so this may not have anything to do with it.
I'd say 2ml/gal dosed two consecutive days killed 90% of my BGA, along with 90% of my anacharis, hornwort and milfoil.
I noticed pretty similar results on some of my mosses. While some pockets of them were untouched, others were nearly obliterated (using the 3.whatever and 4ml concentrations back to back).
However, I've just put in a significant order to InvertzFactory and hopefully can rely on critters to do my algae work from now on. Even though I did not many plants (yes, some did in fact perish), I lost 30-50% of my leaves (depending on species) and 100% of the leaves on my 2 red lotus. They're coming back as we speak, and now I have another baby coming up next to one of the mama plants.
H2O2 is awesome as a treatment, but overdoing it can cause more harm than good IMEO (E becaue I figure after blasting peroxide into the tank in such quantities I've killed enough plants to have formed an educated opinion). Buy some otos and other algae lovers; they're relatively cheap and make great tank additions.
P.S. - After all of this, the green water STILL did not vanish. If the conditions exist to support algae beyond the plants' capabilities, there really is no quick "cure" to your woes. Be patient, find the problem, and be patient some more...