Most reefs of the world fluctuate Between 75deg. in winter to 83deg. in summer. It's my opinion that a temp swing of more than 1-2deg. per day is going to stress the fish. I keep my tank (125gal. with 40 gal. refugium) at 78deg-80deg. I would definitatly get a heater and also figure a way to keep the temp down during the day. I have fans wired to my lights which are on timmers. The PC's are the first to come on and the last to go off and this is what the fans are wired to. I also leave the Air on during the day set to 80deg. In the afternoon when my wife gets home it gets set at 74. The heater flickers on and off all night to maintain 78-79 deg. During the day the fans keep the temp from going above 80.
I have a 135 and I don't have a heater right now, didn't think I needed one till it gets colder. My temp can go from a high of 83 during the day to 78 in the morning. Can this stress my fish out should I get a heater to stop it from going say below 80?
