Sand (or fine silt?) coming from return vent?

[Achilles]

Hi all,

I am wondering if someone can comment (or point me to a thread) on sand coming out of the return vent. I have a sand filter and have noticed lately that when I run it for a longer period of time like overnight, I get small buildups of brown sand (or fine silt, maybe?) on the floor of the pool. My pool floor will start out clean before running the filter, and then will have the small brown piles. As I say, I am not sure what they are made up of - maybe it isn't sand at all. Could it be dirt or sand so fine that the filter doesn't trap it? Besides that, the water looks great, levels are fine, flow and pressure are good, I backwash as required, etc. Any hints?

Thanks!

 

[Smykowski]

Can you get some and put it between your fingers? If it's sand, it will be obvious. If not sand, it's likely dirt or dead algae.

 

[Achilles]

Haven't done that yet with my fingers yet, but according to my wife's toes, and the way it "vaporizes" when brushed, it is very fine and probably not sand. If it's not sand, do I just keep vacuuming it up and hope it stops collecting, or could it be recirculating?

Anyway, I'll get my fingers on it and examine it better.

Thank you.

 

[Smykowski]

Can you post a full set of test results? Any areas of poor circulation that algae might be hiding? Any algae or dust/dirt collecting on a solar cover that could be getting in the water?