You can use hydrogen peroxide to help keep your roots in healthy condition and assist in keeping root rot at bay. The other option (which is better for your plants but more expensive as well....) is using a zyme product like Sensizym, Cannazym which helps keep your roots healthy. Zyme products can also assist with keeping the ph stable in your res as well.

PS....Most zyme products are enzymes so can't be mixed with Hydrogen peroxide.t's one or the other generally.

You need more light for those plants.....the stuff you are using is not doing it for branching and bushiness while growing.