What kinda system are you using ?

I recirculate my dwc system - about 25 gal. total and use a titanium aquarium heater and have no problems .

Find out the actual res. temp w/ the lights out for a while .

I read max oxyg. / aeration of H2O happens at about 62 deg .
I see best growth at 72-76 though , any hotter is askin for root rot .

Peace
Crispi :stoned: