I live in Ellensburg, WA. where in the summer it's normally 95ish degrees. I don't have air conditioning so the house gets sorta warm during the day. My fish tank heater is set pretty low and the tank stay about 79-81 degrees through the day. This seems a little warm for my tetras who prefer 70-78ish degree water. Is there a way to lower the temp is the tank safely? Or to get the tank to stay at a cooler temp. Preferably a few degrees below what it is now. Thank so much for the help.