We recently remodeled, and the contractor (who also has a CA c-53 pool license) was charged with replumbing and replastering the pool. He was subsequently fired for problems other than the pool, but this left us with a pool that was unfinished.
The pool was left basically ready for plaster, with plumbing in place, and old plaster gouged out. There the pool sat for over two years, becoming a black swamp populated by mosquito fish and plants provided gratis by county vector control (one of the few government entities I’ve ever actually enjoyed working with.)
Fast forward to recent times. I hired a new pool guy with >35 years in the business and high praise from customers. He pumped the swamp, installed fittings, and replastered the pool. The pool has been full for about 5 weeks now.
I’m doing maintenance myself, and recently noticed that there are some small black spots here and there that don’t vacuum up. I have been able to dislodge most with the nylon pool brush, but a few persist. Otherwise the chemistry is under control (starting about 2 weeks in,) and the plaster looks pretty good.
[list=2:2xs1otz6]1) Can black algae for that quickly, or is this more likely dirt?
2) I know this is not related, and possibly way too paranoid, but should the contractor have bleached the shell (remember, he had to pump out a shallow black swamp) before replastering to stop any growth that might start from the back side of the plaster, or does the lye in the fresh plaster take care of that?[/list:2xs1otz6]