Hi Fishlore, I am currently fishless cycling a 5 gallon tank that I hope will be home to some happy betta in a few weeks. I have the filter going, obviously, and the heater is set up but not plugged in yet. My thermostat is the kind that sits inside the tank, kind of free standing, and is kept weighted down by small metal balls. It has registered 82 to 84 degrees since I set up the tank and started cycling it -- with the heater OFF. The light's not even been on. Now, my place is not super warm. I live in an apartment in NYC, where it's been 40-60s the last few weeks. The landlord does keep the building warm, and it probably does get up to 74 degrees in the apartment -- warm, but nowhere near tropical. It's only going to get warmer in the summer, though, and we don't have central air. We normally swelter through the summers and have a window AC unit in the bedroom only. I may install a window AC unit in this room (second bedroom) if I can get it rigged in the extra wide window I have in here, but it would just not be feasible to leave the AC turned on 24/7 even when I'm not here. And when it's super hot in NYC, it can be 90-100 degrees outside. So my concern is that the water seems super warm already -- with the heater off and the ambient room temperature no more than 72, 74 degrees. I'm especially concerned about this summer, since I don't foresee being able to provide stable, cool ambient room temperature. So, what do you think I should do? Do you have any experience with keeping bettas at 84+ temperatures? Do you have any ideas about why the water is so warm already? Any ideas about this summer? I will add that my only thought has been that this 5 gallon tank is the only tank of mine that has the hood attached to it. It's been cycling with the hood down, and I'm guessing that may be keeping some heat in, even if it's not coming from the heater. Whenever I lift the hood, a lot of condensation drips back into the tank. Is my only option to keep the lid off to keep it a little cooler? I hope that's not the solution, since it's sort of an eyesore to have the hood open constantly. I'm going to start leaving the hood up for now to see if the water cools down much. I'd love to hear your thoughts though. Thanks in advance for your help!