Can Sched 40 PVC be safely painted?

Last year I hard plumbed my 24' AGP with white Sched 40 PVC. The filter and plumbing all get direct sunlight throughout the day. As a really, REALLY low tech way of solar heating, can I paint the PVC black and not affect its structural integrity? Can I do the same with outside of the filter tank (it's a Hayward Xtreme cartridge)?

Thanks in advance.

Sched 40 doesn't perform well when subjected to heat. However, you should be able to paint it with a latex-based paint, but I would strongly recommend against using anything but a low pressure flow through it unless you are relentless about always running it in sunlight so the water inside cools it.

Remember, a slow flow that produces hot water won't heat your pool as much as a heavy flow that produces water just a few degrees warmer than your pool.