The water temperature in my pool in Korat varies between around 23 degrees between December and February and up to 33 degrees during the hot season.

I find 28 degrees nice for swimming lengths and just messing about with my daughter, but 23 degrees just a bit too cold for comfort (I'm getting soft in my old age).

I've been considering some kind of simple solar heating system for years to cover the 'cold' months but have never got round to it. I was thinking about using black hosing feathered across the far side of our pool house (out of sight) with a small pump to keep circulation... or something like that. I've been told that in Australia people sometimes put truck inner tyres into pools to keep the water warm during the winter. We get the sun during the winter, but I think that would spoil the pool's appearance a bit!

But... there's been a lot on UK radio lately about the benefits of cold water swimming in warding off dementia. I'm no spring chicken so maybe I'll just leave it as and hopefully not get any more senile.