Hello everyone i just joined the forum. I have started cleaning pools and have been doing this for about a month now. My brother and i are working a guys accounts and will be taking over them. currently we have a big pool right now that has this crystal like stuff at the bottom of the pool that accumulates over time. Its in the pool every week when i go to service the pool. When i pull it out of the pool and let it dry out it turns into a white flake when i rub it between my fingers it turns into a kind of white powder so the stuff is soft. Now the stuff started to show up when my boss drained the pool and filled it back up. but it didn't start to show up until about 6 to 7 months later. I took it to my pool store that i get all my pool supplies from and surprisingly non of them really seemed to know what it was. but what they said it most likely was was calcium but they weren't sure. I've done a ton of research for this and have only found a few people with the same problem but never really got a forward answer on how to fix it. one of the things that i read was that it might be a fungus of some sort. I know its not DE either. So before i go and try anything i wanted to see if i might be able to find someone that has or had the same problem and has fixed it. If you guys could help me out that would be great because the people i talk to don't seem to have any idea and i would hate to loose this customer.