Could it be cal-hypo residue???

[lewispool]

I posted earlier about something in the bottom of my pool. I first thought mustard algae, but that is not it. Numbers are good, no FC loss overnight, no cc. Deep end is slightly cloudy. I then started thinking it must be sand, but it is fine particles that seem too small for sand. After doing some internet research, I am now wondering if it is residue from the Cal-Hypo I use. It is a brownish color though and in significant amounts on the bottom of the pool. UGH, I think it must be sand... IDK. We replaced laterals and sand last year. We used the right sand from the pool store and had no problems all last season.
Any thoughts?

 

[Bama Rambler]

If you can gather a sample of it you can test it in a couple of ways. One is to try and crush it. If it crushes relatively easily it's most likely not sand. The second is to drop some of it in a small amount of muratic acid. If it fizzes and dissolves it's most likely not sand.