On Sun, 06 May 2012 10:05:48 -0500, gonjah wrote:

I don't know but nice pool.

I'm still unsure if the white is calcium or if the white is the lack of
blue.

For example, here is a closeup of the blue and white.
http://picturepush.com/public/8203361

The white on the tile must be a deposit of something.
The blue below it must be the pool plaster.
But what's the white below the blue?