Normal opening except something sandy in the pool

[Jnet]

Happy spring, everyone! This is my 5th time opening my pool. It's usually pretty predictable. We get some organics that get past the mesh cover over the winter, so the water is a little cloudy, but it was still 53 degrees, and a couple days of running the filter and it's nearly crystal clear. When I opened, most of the numbers were pretty good:
FC: 0
pH: off the chart high
CH: 420
CYA: 30
Salt: 2200
I added 12.5% lc, and it's holding. In total, I added 1.5 gallons of MA with almost no effect, but it had been sitting through a rough winter, so it's possible it was bad. I bought a fresh gallon and the pH came down as expected. So the weird part: my cleaner keeps picking up what looks like silica sand off the bottom of the pool. Maybe 1/2 - 3/4 of a cup with each run. I have a cartridge filter, so it's not filter sand. Could the really high pH have made something bad happen? There's been no construction or anything in the vicinity of the pool that I can think of that could make this happen? Any input is appreciated.

 

[ajw22]

MA does not go bad over a winter. 2 1/2 gallons of MA on opens not surprising. My pool took 3 1/2 gallons of MA to get pH into the 7s.

I doubt anything bad happened. You just picked up the sand from winter runoff.

 

[mknauss]

One way to check any unknown material pulled from the pool, is to pile some up and drip some acid on it. If it fizzes, scale, if not, likely sand or other dirt.

 

[Jnet]

Mknauss: Smart! I knew there was a reason I hang around here. I'll try that. My fear is that it's my plaster somehow going back to Earth... But I think it's just sand.