I have these white, thin, pieces of stuff that comes out of my returns. Tons of it. It is also the stuff that you find in your cell when cleaning. What is this stuff and how do you keep it out of your pool? I test my pool on reg. basis and all is well other then adjustments for ph. Saltwater - intellichlor. My pool is about 4 yrs old and we first started noticing it last summer. EVery once in awhile we would find it on the floor of the pool (pebble tec). But this summer it is a constant issue! Suggestions?