Insulating above ground splash pool

[Roksan]

I have a 12' dia. splash pool, and want to place some insulating material between the pool and the ground. The pool is 32" deep, and holds about 7000 litres of water.
Anyone got any ideas for a suitable product to insulate with?
I intend to lay down a sand base on top of the soil, followed by an insulating layer. Ideally I could then do with a layer of felt (or similar) to provide an even, smooth surface for the pool liner to sit on.
Somebody has recommended Celotex boards for the insulation. Anyone used them before?

 

[masona]

I have a splasher pool and just wondering why do you need to insulated the floor area, is it for comfort ?

I have a concrete base with a rubber liner on top of it. I got fed up with burnt smelly grass round the pool area

 

[Roksan]

Main reason I want to insulate is because I am about to fit a pool heater, and heating costs are vastly reduced if the pool is well insulated.
The surface of the pool is insulated with a solar blanket, which also helps the pool absorb some heat from the sun (if we ever get any in the UK).
Eventually I plan to fit a timber carcase and decking around the pool. When I get round to that I'll also insulate the walls of the pool.
There is an insulating wrap available for these pools, but I'm not sure how efficient it is - it looks like the pool has been wrapped in cling-film!

 

[david and julie]

Why not polystyrene? it is very strong in compression.

 

[Roksan]

My only concern with using polystyrene is if it breaks and becomes uneven under the pool. I suppose if it's butted together well and the sand is well levelled it should be OK. Worth a try as it's a lot cheaper than celotex.