I have an aquarium that I built into the wall in my living room that is 8 feet long and close to 200 gallons. I had to put a heater in it due to the fact that I keep my house at 68 in the winter. I use a 300 watt heater that has a scale on it from 65 to 85 degrees F basical that is up to close to 30 degrees C... imagine if you used it without the built in thermostat it will get hotter than you want. You will just have to control it via a sealed LM35Z and some software.. I forgot who made it but if you need me to, contact me offline and I will find out for you Eddie Turner, kc4awz -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads