Clone Knockout Punch

was wondering what everyone uses in there dwc to keep there roots happy... I been using beneficial bacteria southern ag garden friendly fungicide...But have see people using h202 and was wondering how that worked and what kind of h202 they use..I have also used hydroguard along with keeping water temps in check...southern ag is just cheaper then hydroguard ..Just looking for someone who runs a sterile dwc reservoir and how they go about doing it and in cost effective way.. I have also seen people say they have used pool shock kinda sacred of that.... ON my next grow wanting try run a sterile reservoir and help would be appreciated