H2O2 is good for hydro growers as it has multiple benefits. I use it in all my hydro/aero grows not in my soil grows as its not really for that. Dont use the store 3% stuff at like walmart or such as it has additives that arent so good and can chnage the taste and aroma of the buds. Use like grotek Super H2o2 which is 30%. You will use 3-5 drops per gallon of water. The benefits are you get o2 to the roots which makes healthier plants, prevents stress,makes vigourous growth, stops alage and mildew in the system and on the roots. It also helps the plant uptake food better and faster. Its fine to use with most nutes but not so good if you use an organic microorganism type additive like Dr Hornsby as it will kill the bacteria.Its great stuff htough when used correctly