Thanks for getting back to us.

I'm leery that it's calcium, though I can't quite put my finger on why. If it's not the wall foam (and the wall foam would be secure at the top, it's floating up the wall from the bottom! *) then I'd be more inclined to say that it is oxidation from salt.

* If he was able to reach his hand behind the foam from the top, the foam isn't very well secured! (and if it's that easy to reach behind at the top, it's worse at the bottom, where water can rise behind it!!)

I don't know the topography of your pool location, but I'm assuming your pool sits in either a hollow or on the down slope of a hill. Probably, the best fix would be to install a curtain drain to divert the excess water away from the pool. Another option is to install a well point and sump pump. (if they hit water when they built the pool, they may have installed a well point)

If I knew more about you pool and where it sits, I could advise better.