Heating a pool is stupid.

Seriously you get a pool so you can cool off in the summer and get exercise when its hot, if you heat it (granted not hot but still) then why bother? If you get cold it means you aren't moving around enough to get your blood pumping to keep you warm and again its a waste.

If you want a heated pool just buy a fucking hot tub so your lazy ass doesn't get cold on a hot day.

I know when I go swim at the river or lake it sure as hell isn't heated and I stay plenty comfortable.