I have a brand new in ground shotcrete pool with Krystal Krete finish. Quartz Pool Finishes | Krystalkrete. It was filled March 18th. I am battling black algae for the past two weeks. I have a pool service and technician has not eliminated it yet. I have the owner coming out today to look at it. I am thinking I may have a phosphate problem. I always thought that black algae was a problem in older pool not new pools. I am wondering if this could be a construction issue? If so I will need to contact my pool builder.