This past weekend I had the two 18 watt PCs running for 12 hours a day. On Saturday I noticed the tank got up to 86 degrees!
I asked my wife to run out to the store to find a small and quiet fan to help cool the tank and she came back with a Lakewood High Velocity Personal fan! This little bugger is only about four inches in diameter and pumps a good bit of air out. For now, it is only blowing on the PCs and has got the tank down to 79.2 degrees.
Now all I need is an auto top off solution!