It's been reading over 1000ppm higher than the pool store, then salt dropped to 400ppm knew I needed to clean and I find this...( only a year old)

That is copper carbonate, 30 minutes diluted muriatic acid bath for the cell, remove remaining fouling with brush. Stop using copper algaecide. Get your metal levels checked in your water.

Thanks, every time before for the last 7 years I had never seen much of anything in there to clean, but did it anyway. So I was shocked to see this blue mass.

In the past I had used "Yellow Stuff" to treat for algae but my pool store said it was discontinued and recommended BioGuard algae complete which has copper sulfate in it.

I would love to hear any suggestions on a copper free algaecide.