forgot, I try to keep my tank at 80, it ranges from 79-81 often, and I have seen 76-84, thats about the worst Id like to see it too.
I have 40g total volume, and I would like more volume some day, it actually fluctuates pretty fast, nanos could fry in an hour in the wrong conditions.
I have two fans, a small one in the sump, and a large desk fan like 10", is on the desk next to the tank, it turns on if the temp is above 80, so some days, it runs all day, I see up to 1/2g more evap on hot days, if my tank went up. House AC, and open top tank.
I also target for the 79-80 degree range. I just pulled out the exhaust fan I had in my fish room and installed a window A/C unit. I will have to see what happens in winter when I want to exhaust some of that "fishy" smell from the basement. Maybe I will reinstall the fan for winter (what fun that will be)!
I also have open tops on all of my canopies to let out some heat from the MH lights.
Being located in the basement also helps keep temps down.
I shoot for 80 and it stays at 80-81. I use a chiller because the room it's in doesn't have a/c, and during the night I turn on the fans in my canopy so that the chiller doesn't need to run. After I voted I saw the option for open top, which I also have. Total system volume is around 27 gallons.
I actually used to live in Jacksonville Florida, and the heat isn't as bad as everyone thinks. You go from your air conditioned house, to your air conditioned car etc etc. My house down there was always cooler than my apartment here.
i'd always run my tanks cooler than most, 76-77, and thats been aided by having it in the basement. but i've been slowly ramping it up the last week or so and i'm going to try running it at 80 for awhile now. we'll see what that does to my electric bill. the heater has been on a lot more as i've been raising it.
well our house has ac and when its on at 77 the tank is at like 80 during the summer and the winter with the heat on the tank was at like 77. i dont have a heater and its open top with 260watts of compacts over the 55 and no fans. at night it only drops about 1 degree. power heads are keeping the tank up to temp at night also i guess
my tank runs between78 to 83 had to change the lights to come on at night. when i was running them during the day the breaker would pop when the ac unit kicked in.also have a break in the halide lighting 3 1/2 on 2 off 3 1/2 on again. hyaven't poped the breaker yet like this(knock on wood).
I shoot for 78-80. In the summer I have a large box fan that blows at my tank. Seems to keep the temps just right. I do not allow AC in my tank room, because I always have the window open in that room to keep my PH up. Not sure if that really matters though.
When it gets really warm in a tank I break out my "poor mans chiller".
A one gallon plastic water jug filled with RO water sits in my deep freezer until needed. Just pull it out and place into sump and let it thaw out. Actually does work, not as well as a "rich mans chiller" but it does work. If your sump will not accommodate a large jug just use a bottle that will fit.