Think about the issues that people have with loops without introducing macro-biology to the picture. I can't imagine a world where this worked, unless you were willing to put in a RIDICULOUS amount of upkeep that would give you stress-hives and cause you to go bald prematurely. I also think that you are over-estimating the capabilities of a water filter. I'm less concerned about the immediate heat issues and more with the notion that you will likely destroy the components in your water loop quickly with this idea. I would be truly happy to be proven wrong. Also, if this is likely to kill your fish, than what's the point? If this was successfully completed it would be AWESOME. But if it were successfully completed all except that the fish died right away than you really haven't done a whole lot IMO. Either way good luck! Pics are a must!
