Since I'm not a pool owner, can someone explain to me why you need a pool heater in the summer? Isn't the whole point to cool off from the summer heat? While I had friends with pools, I never heard any mention anything about heaters or propane. Is this a regional thing?

As a member of a pool owning household, I am equally confused. I've never even heard of a pool heater although we've used a pool cover for years. It sounds ridiculously inefficient.

The idea is to have the water around 80 degrees. At that temperature, there is minimal chill on entry. With bodies at 98.6 degrees, 80 still affords relative coolness. After the dark evening and perhaps 70 degrees with evaporation, the water can chill.

You can try ocean swimming. When the water is under 70 degrees, it does feel chilly at entry. As for me, I once entered the ocean at end of March in NYC. No more: too old.

Are you responsible for the rise in sea level?

[That was a joke. And probably not a very good one. I just couldn't help myself.]

What they call summer we might call early spring...

Thanks for the explanation. I have to agree with the other commenter, pool heaters sound pretty inefficient, but I grew up in the south, so too cool water was rarely a problem.