Hi, Nicole,

Thanks for your answers....helpful.

I believe the dirt is coming from your filter somehow. This may be incredibly difficult to do, but one way I can think of to identify that is to redirect the water so it makes a stop before it goes back into your pool. (Sort of like a white settling tank) so you could identify any very fine particles coming from the filter. The overflow from that "tank" could then be directed into the pool. Are all your lines hard PVC?

Perhaps easiest would be to thoroughly empty all the sand from your filter and rinse it out well and then turn the pump on with no sand (or fine dirt) in the filter at all....If the filter is the source, the dirt will stop. In so doing it would give you an opportunity to carefully inspect the laterals for any small damage that may be letting very fine particles thru.

Those are troublesome experiments but, based on this entire thread and your descriptions, the filter seems to be the logical culprit.