I found a potentially unlimited source of free used industrial strength 1.6kw UV water sterilization tubes. From what I have been able to find out about these is at full power they sterilize water at around 300gpm per tube. With the power source they are supposed to have they can run variable power from 20 or 25% up to 100%. So if 100% = 1.6kw then 25% should be about 400w. They start with a thousand or so volts and at full power use around 7 to 8 amps at 200v. I powered one up with a microwave oven transformer. But since the microwave oven transformer is a constant voltage source it flipped the 15 amp breaker it was powered by. Because as the tube warms up the resistance decreases. So the constant voltage power source will just try to push more and more amps through it until the bulb, transformer fries or the breaker flips. So I need a constant power source, like a pulse start metal halide ballast transformer. If I got a pulse start 400w metal halide ballast that would run the bulb near 25% power and would be plenty for a tank of water I think. Also 400 watts is easily getable from a generator or power inverter.