Ok I am in the process of setting up 5 large ponds. They all will be insulated with 1 inch foam on the bottom and sides. I will be making plastic covers for them. Each pond will be around 450 gallons. I will be linking 2 sets of 2 ponds together making about 1000 gallons per setup. And the solo pond will be about 500gallons. My house is always at 70 degrees so I only need to bring the temp up 6-8 degrees. What do you recommend. I have thought about 500 watt titanium heaters in each sump. Also have thought about a space heater with thermostat. What is the safest method? I will be keeping very expensive fish in the setups and want reliable equipment. Please help me out. 
