Hi
I intend to build a swimming pool.
30 feet x 10 feet. Partially above ground (2ft) and 3 to 4 ft below
I intend to use a liner.
I am going to use Solar Power to partially offset heating costs.
Also an insulated swim pool cover.
I've looked at panel type pools, concrete pools, etc.
No one seems too concerned about insulation as part of the design.

I was going to make one with concrete and blocks but had the following
thought.
Why not do away with the concrete.
Build walls and dig to depth, line the pool with something like Kingspan or
50 mm polystyrene panels ensuring all surfaces behind the insulation have no
hollows.
Add a liner then fill with water. ( I exclude such things as skimmers,
drainage for clarity)

Your thoughts please on possible major issues with this concept.

regards Hal