I had an issue with my sand filter blowing sand into the pool, but it was not powdery. I could pick it up with a fine net and feel that it was gritty.
You might be able to catch some water from your return using a skimmer sock or a nylon, so you can look at it more closely and feel it.
You might be able to catch some water from your return using a skimmer sock or a nylon, so you can look at it more closely and feel it.
