I'm trying to figure out what this white powder is that my cleaner keeps picking up. It has about golfball size clump of white powder each week. Also the white plaster on the walls feels gritty. I don't think it's de since it seems to be coarser even after it dries out. My calcium was out of whack earlier in the summer. Around 600 and my cya was well over 100. The dot disappears almost instantly. I drained water twice and my numbers are as follows. My pool is also salt. The powder was there before converting to salt a few weeks ago.