Weird fungus, 13L 11D flowering?

My plants are in clear containers and i can see the roots... the roots have grown through the holes of my pots and were sitting in water and turned brown. i cut that shit off. other plants have like a white hairy fuzziness to them. i think that if i leave some tap water in a 2 liter with the cap on it and bring it to room temperature so it doesn't shock the plants, the chlorine will help kill the fungus, i also want to put some hydrogen peroxide in the water to kill the fuzz. should this hurt? its H3O right? just water with extra oxygen? any advice? and my plants are flowering under 13 11 . is that beneficial. i heard extra light equals better yield.

Its H2O2 for the peroxide, as to the roots/possible root rot? what type of grow system? soil or can i assume hydro?

measure carefully (peroxide can be used)!

good ol dirt. will the peroxide and chlorine hurt the plant and kill the fungus?