Commercial solar pool heaters are expensive, especially if you need multples. Here's how you can cobble together a solar collector/heater for your pool and create interesting 3-D optical illusions to entertain (or frighten) your neighbours and friends.
It's not as hard as it looks. If I can do it, anyone can do it.
Step 1: Why Another?
There are a lot of pool heater instructions on the internets; this one culls together the best parts of each (sort of) and provides more specific advice for the pumping situation.