We get brown dust in our pool. It is very very fine, will suspend in the water if stirred up, even by vacuuming. It is worse in dry years, and this one sure is dry out here. We are out in farm country in a very small town surrounded by corn fields. The sand filter will catch some of it, depending on how patient I want to be about backwashing and vacuuming frequently. I've found that the best way to deal with it is to give it a basic vacuuming, turn the filter on high and have the kids jump in and swim and splash like crazy. Then I leave the filter running all night long. The next morning most of it is gone. If the rains don't come, it appears a little more each day.

By the way, it IS a bit slimey to the touch but it absolutely is not algae, it is just dust from the fields.

Jean