Pool chemicals are where they should be, we have a 20 foot by 48" soft side intex pool. We have something going on on the bottom of the pool. Looks brown, but is green in the vacuum filter. when you vacuum it separates like powder, but clumps together when settled...is this pollen? If so any ideas what I can do. I vacuum and vacuum, but the next morning there it is again. I know I'm stirring it up some when I vacuum as I can see it doing that while I'm vacuuming. Thanks for any help you can offer, I really appreciate it!