I have one tank that doesn't have a thermometer on it and I can go for a month without checking the other 2 . Having said that when the heat gets to the point where I feel a need to turn the AC on (usually when it goes above 25) then I check on the big tank to make sure the temp hasn't gone too high.

So to answer your question its not the tank inhabitants but how hot I'm feeling that makes me react :lol:

The 1 month old Lifegard Time & Temp I put on my FOWLR says it's at 45.1F. I know my chiller isn't THAT powerful. POS Time & Temp.

I live in Calgary where it rarely gets hot outside and have central air as well. Tank never gets hot.

Ok so how hot is too hot? and doesnt it take a little while for the bleaching to occur? so that by the time the coral looks sick its too late?

I came home yesterday to find my tank in the high 80's.........some corals didnt like it much and you could tell just looking at them.........I put some ice cubes in the sump and lowered the temp. the corals perked up with in 30 minutes......I have someone at home today to keep an eye on it.....

My tank is in the basement so even during the hottest days it never really gets over 81Deg.

Last summer I tried a nano on the upperlevel but gave up becuase I could not keep it below 85 on hot days.

My SPS tank has hit 88 the last few days but the majority of the corals appear fine. The only thing that looked like it hated it was the popsicle pocci that had some RTN two weeks ago after I moved my tank. But it was already stressed so I'm not surprised that the added stress of the heat caused it to start bleaching.

I use a fan on a timer with the light but sometimes it almost gets to cold on cool days

I dunno, routinely my tank sits at about 78-79. The tank has gone up to 85 a couple of times this summer when the chiller fuse has blown and I haven't had any losses. Too hot = when it feels like bathwater. Usually I put my hand in and go ahhhh, nice. When its too hot I go argggh! stupid chiller! you suck!!!! and my husband rolls his eyes :razz:

The bleaching doesn't necessarily occur as the temp rises, sometimes it occurs on the way back to cool. Depends on how fast/slow you "fix" the temperature issue.

summer heat
 

I use a window A/C unit to keep cool. It has a built in thermostat. Set the temp, and walk away. My tanks only raise max. 1deg. on the hottest days. At around $200, it's an inexpensive way to keep one and all happy.