Over the past 6 months, my pool has begun to develop spots. These sports are at the bottom of the pool, in both the deep end and shallow end.
I do not have any items falling in the pool (coins, nuts, etc.). I get the regular leaves, but I have a Hayward pool vac that runs daily.
I've tested my water consistently over the past several months, even bringing in samples every month to a local pool supply store for them to verify and check additional things. My pH is good, chlrine is good (it's a salt pool), TDS, Phosphates, Alkalinity, calcium, etc. Everything seems normal.
A wire brush will not scrub these off either.
I'm attaching pictures. I have no idea what this is, I hope somebody here does.
Thanks in advance!