I had a 24-plant hempy SOG grow for about 3 years and it's pretty rare to see root rot since usually, the res only lasts a couple of days before needing to be re-filled. If it's an ongoing issue, you should take the plants out of their containers, give them a root soak in H202 solution (about 50/50 mix of 3% with water) and sterilize the containers. Re-pack with fresh perlite/vermiculite and re-fill res with 1/4 - 1/2 strength nutes. If the roots aren't too bad, that should get them going again!Yes hempy is hydrid dwc grown in perlite, symptoms were damaged leaf edges. I flushed with water and hydrogen peroxide, things were looking up for a few days. Opened the tent yesterday and the blue dream girl had a ton of fresh leaf damage and the beautiful amnesia girl was droopy as a colander full of cooked noodles. The res water smelled like dead fish, ugghhh. Did a bunch of triage, cut out brown roots, an upcan plus more flushing with h202. The Blue chick might pull thru not so sure about Amy she looks toasted.
BTW, I always recommend against organics in anything hydro, too, since IMHO it only encourages bacteria to grow in the res. I also recommend looking at Dutch Masters Zone product. It's a root zone "optimizer" that uses copper as a fungicide, which means it can be used in conjunction with H202 in the res. Those enzyme-based products typically do not play well with H202 since it kills the enzymes.