You know dude, not to be all "Capulator's bennies are probably the answer" all the time, but this is one of those times. Because bennies are a great line of defense for roots against any pathogens, and frankly Capulator's bennies offer better value for your dollar than anything you can buy in a store. Especially if you turn them into teas.
Carefree Enzymes makes an enzyme tailored to hydroponics now. I haven't heard anything about it. I use their Pond Protector(stage 2) at the rate of 15ml/100 gallons. So my quart for like thirtysomething with shipping will treat like 6000 gallons.
I was going broke paying for all that
hygrozyme.