I use H2O2 to keep my rez and controller bucket nice and clean. I use 2 ml/l of 35% h202 every 3-4 days and it stays very clean and bacteria free. I just finished dumping and filling the rez for the first time in a month (I use Lucas with addbacks) and there was no bad odor or nasties on the bottom of the tank. Love it. This can, of course, only be used in a sterile, in-organic feed. H2O2 does not care about your organic "beneficial bacteria" and kills it. Those things don't have any place in a hydroponics setup anyway IMO, but to each their own.
To anyone reading this thread wondering if this system is worth the $$. The answer is yes. I considered doing a controller bucket DIY using one of the guides I found online but to do it to really match with dual vales on both high and low water marks makes it a real pain in the neck. CAP makes a great product here and the controller is worth the price of admission. For all you ebb/flow guys moaning about the lost height from your tables and reservoir, Chk this out!!
I will say that the expansion pots can easily be recreated using everyday stuff found in any hardware store so only get those if ya got some $$ to burn.
Good Luck!