With the warm weather we have been having, coupled with being in a hot dorm room, I noticed that the temperature in my tank is hotter than I'd like it to be. It's currently at 80F, which is a little over the recommended temperature for the cories from what I've read. How can I cool the tank down so it isn't so hot? It probably isn't a big deal now but I'm worried for next summer. This past summer the tank got over 80F just due to the external temperature (the tank heater is set at 78F). My house doesn't have air conditioning so I can't change the temperature in my house apart from the numerous fans we use. I didn't get the cories until the end of summer so it wasn't too hot for the betta but it will be for them. What can I do to change this?