Since this last came up I have taken the line out of my sump. It was just too hard to keep the tank temp up. I looked around for a constant heat supply and decided that my MH ballast would work just fine. My ballasts have the metal fins for cooling. I just ran the water line back and forth under the ballasts. I'm not sure how much my line temp has risen but it's definately warmer to the touch. And it keeps my ballasts a little cooler as well so thats a bonus. Of course it only works during the day but what the heck, it's free heat.
