Currently I have been using H2O2 everyday, because I've had some heat issues and got some root rot. If I don't use it that nasty brown film (algae? or bacteria?) comes back with a vengeance. As of today it looks like I finally have the heat issues taken care of(re-did the whole exhaust system). So for right now I have them in a DWC of RO, CalMg, H2O2, and Superthrive. The reservoir level is almost to the top of the net pots. Figured I would do this for two days to try to get rid of most of the dead roots. Once I'm back up and running at full strength, I would like to use some H2O2 as a preventitive, but not as much as i have been.