My old SPS reef used to sit 82-84 and my current mixed reef sits at 78-79 and I see no real difference. I do think the slight temperature difference changes the metabolism of everything in the tank though, so I find tanks are easier to maintain when they are kept under 80.

I run my tank between 75-76 frag tank 74 and seahorse tank 74.

I think temperature (within the range of this poll) has a greater impact on fish than corals. Corals will adapt to a variety of temperatures and seasonal temperature swings quite readily, and while their metabolism might increase/decrease depending on temp, it's already quite low in comparison to fish. I think running a high temp is more stressful to fish, both because of higher metabolism and lower dissolved oxygen at higher temps.

I have 8 fish in my 93g cube, and run my temp just below 78.

Fish tho in the wild live in the same place the corals do undergoing the same swings i personally think keeping our reefs as close and possible to " natural " environments as we realistically can is the best thing we can do. There are studies done showing temp thats too low or to high has effects on both corals and fish over long term.
Same as keeping a hermit crab from Vancouver shore in our reef while it will survive some weeks to months and adapt to our tank it isn't suited for the higher temp compared to its natural environment of colder waters, i would assume taking a fish or coral from Indonesia or Hawaii and cooling it down to 78 deg for example would have the same effect.

But all in all there really isn't too many studies out there to back up any of our claims so we are mostly going on opinion and i guess at 1:48 am ( when i should be sleeping not thinking about reef tank temp ) thats my opinion lol :lol: