Well, I used to be fine doing water changes because my room was 76 degrees and I'd just leave my water out to adjust to room temperature and that meant it would be the same temperature as the tank.. My problem now is that I live in a dorm now and my roommate likes to keep the temperature at 70 in here. Brrrrrr! I just did a water change and he's floating in his cup in his water because the water I added was a lot cooler than the 80 degree water in his tank and the heater isn't heating it up very fast. So he's floating in 74 degree water right now. I feel like harsh changes from 80 to 74 even if he's being floated are going to stress him out.
So, how would you folks suggest getting my water to exactly the right temperature before I add it to the tank? Thanks. :) Is there some kind of water thermometer I can get that will work quickly and accurately? Thanks!