u/AmphibianConfident86

There’s this white fluffy stuff on the bottom of my pool - anyone have any idea what it is? It doesn’t show up well in the photo but it kinda looks fluffy like mold - it isn’t. When I brush it it dissipates into a cloud of white dust.

All of my water tests are within range except alkalinity is high. I’m thinking it’s calcium, but curious if anyone recognizes it to confirm.