Cloudy water and algae(?)

[zenzic]

I had an equipment failure that took long enough to resolve that my pool turned a lovely shade of green. With everything in working order, I'm SLAMming it and have the following measurements before starting SLAM:
ph: 7.4
TA: 48
CYA: 70 (I know it's on the high side, but I have a stingy private well and refilling isn't always an option)
CH: 180

Current chlorine readings:
FC: 25
CC: 0.5

The water appears to be clear of algae, but is still cloudy with what I assume is dead algae. When I brush the bottom, it puffs up in clouds. I'm hoping it'll clear up with time and effort.

The problem I don't understand is this black "stuff" on the sides. I thought it was black algae and tried to treat it as such, but it neither matches the pictures/description of black algae here nor does it respond to the recommended treatment, so I've probably misidentified it. It isn't slimy and I can't scrape it off with my fingernails. These are the best pictures I could get of it. It's hard to capture.

Can anyone tell met what this is and how to deal with it?

 

[ajw22]

How do you measure a TA of 48?

The black stuff could be metal staining - copper or iron.

Complete the SLAM Process and pass the exit criteria and then we can work on the stain in your pool.

Better to work on one problem at a time.

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

 

[zenzic]

Weird, I thought I'd replied, but it apparently didn't go through. The TA measurement was apparently just a typo. I've finished SLAMming and everything looks good (chemically). Now I'm going to drain some and refill to get the CYA down. Of course, this will mess up my chemistry, but it might give me a better look at what's on the sides.