Huuuummmm :-? I bought a chiller for a grand
Up here the tank temp would easily get to above 30C in the afternoon. At the moment I have the tank sitting at 25.5 with the chiller set at 18C (Found out that the thermostat had drifted about 7deg and 25 C was actually over 30 :evil: Of course it drifted while I was on holiday over Xmas/NY. Fortunately, I didn't lose anything.
I have found in my tank that the livestock, particularly corals, start to stress at anything above 27.5 for an extended period. I am sure that there will be others that will say it is fine at that temp, but not in my experience.