Big black spots in the pool how to go

[aboloqmn]

I bought a new house about a month ago and this problem was in the swimming pool. I am trying to adjust the chemistry of the swimming pool because the acid is high and the alkaline is low, but these black spots do not go away, does anyone know how these spots go
https://youtu.be/7lYG8ledx0A

[PoolioMan]

Most likely black spot algae. In short, you'll need to scrub them away, then follow up with shock treatment and maybe an algaecide. They can be a real pain to get rid of.

[Teapot1]

Algaecide unless is copper based won't touch black algae normal stuff isnt strong enough. Neither is shock unless you can get a chlorine tablet on top of the marks. You dont say what the construction of your pool is and dont do that if its a vinyl pool. Specialist chlorine dioxide treatment can help but black algae as the pool industry calls it is wrong, it is a cyanobacteria and very persistent.