About heaters, I didn't have heaters in my tanks all summer because I kept my apartment warm. Most of the time I didn't use the A/C unless the temp in my tanks got too hot (over 85). But there was never a huge fluctuation in temperature. My 5 gal. stayed between 80 and 82 all the time. It was only my one gallon that would fluctuate a bit more. I didn't have to get heaters until September. So if your office temp stays the same all the time and is above 76, I wouldn't worry about a heater. Usually offices are not kept that warm, though. (I know my office isn't! I have to have a space heater under my desk and wear layers to work in order to keep comfortable!). So just make sure you have a thermometer to monitor the temp and if the water goes below 76, then you need to get a heater.