I am in agreement...way too much peroxide. If I use peroxide...I use about 2-3 tablespoon per rez x3 times, because I use 10 gallon tubs and you use 30 gallon tubs...So, 6-9 tbs. per rez change.

Bognote...people always forget to mention about h2o2.
If you are using any organic ferts or additives, then peroxide will kill all the bacteria, both beneficial and detrimental. so, If that is the case...then you want to find a good enzyme product like sensi-zyme or hygrozyme. I have both. also, there is a product called Liquid Karma you could check out. I have never had one hydro store/expert say 1 bad thing about Liquid Karma.

I have used hygrozyme and Liquid karma going on 2 years now, and I can tell you without a doubt that both products are exceptional. goodluck...checkya later.