This project was a smashing success! Every hour that I run this, it saves us 1500 watts of grid electricity per hour which is what our 'old' pond heater consumed. The sky is the limit on this too. I could route part of this to heat our garage, my workshop, etc. Next year, I plan to route a leg of this to heat our green house - fresh veggies all winter!
Step 1: Aluminum vs. Copper
I want to pause here for a moment, in case it isn't evident why I chose to use Aluminum tubing over Copper tubing - the same reason you don't throw copper coins into a fish tank.. using copper tubing will kill the fish.