are you using city water ?????????? if so chlorine could be the problem . Its very bad for the plants . should fill the res. with bottled= sterile water distilled i believe any deposit bottle water but do not use city water ..... some people say if u let city water sit for 24 hrs it will sterilize B.S is what i think the calcium and chlorine build up in that 24 hrs and u can visibly see it so i would stick with clean water .........i kept water at 68 room temp 75-83