In article ,
"Mr Sandman" writes:

ta for this. So King span is strong enough? cool. Yes it is an out side
pool situated in France. I will be heating it by solar panels and my aim is
to make it useable for as much of the year as possible.

Ok, so i go with king span. Do i go with their thickest sheet or does it
matter much?

Going from nothing to 25mm generally makes a big difference.
Increasing the insulation above that makes much less difference.

By far the most important area to insulate is the top of the
pool, where the warmer water will tend towards, and heat loss
by evaporation and wind-chill is significant.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]