Green stains on pool wall

[Vanitynglory]

I have green stains on my pool walls. Tried to clean with a brush but it is not going. The pool water and chemistry itself is good with just shock needed per the pool store. I already shocked it twice but it is not going. Any ideas on what I can do? See pictures attached.

 

[mknauss]

Welcome to the forum!
You need a proper test kit. I suggest the TF-100 / TFPRO or Taylor K2006C. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.
Once you get your test kit, run a full set of tests and post the results here.
The staining may be organic or possibly metal (copper).
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool