That was another problem I had, almost forgot LOL. I had to keep a heater in the sump, and a couple in the some tanks to keep the temp up. Since each tank drains to the sump, you may not have that problem. Looks friggin sweet Bud. You will have lots of room to grow lots of fish brother. You may want to try to make some kind of lid for the sump and the tanks to try to hold as much heat in as you can.