This season I have had an incredible problem with my pool. It appears to be a case of pink slime / white water mold, but you never can tell. Long story, but bear with me:
It got to the point where - after brushing and vacuuming - in 2-3 days, a 1/2" layer of jellyfish-looking white blobs would attach themselves to the side and bottom of the pool, with a standard chlorine residual of 2 ppm or so. My local pool store said this was the worst case they had ever seen, and even sent samples off to be looked at. They put a treatment plan that included borates and shocking, but it didn't keep it from coming back. It infested my sand filter, gumming it up completely, and all of my laterals contained horrible amounts of gloppy **** that gummed everything up. We flushed and added new sand. We ensured every little nook and cranny was cleaned.
After trying to treat it in this way, I got to wits' end -- only 3 options left, continue some sort of treatment plan, drain and refill after spraying everything down with bleach and letting it sit, or create a lovely rock garden and patio out of it. Because of heavy rains this year, draining really isn't a possibility right now so I decided on a "go-for-broke" treatment plan that I devised. It was simple - add chlorine until the pool reaches 20 ppm or so and let it clean out what it can. 6 hours after adding 100 lbs. in 20 lb. increments, the pool only had a FC reading of 1 ppm. That's right, after ONE HUNDRED POUNDS, it showed only ONE ppm. An additional one hundred pounds brought us up to the 25 ppm mark, and I held it there for 5 days (an additional 25 lbs was required). Once Cl PPM reached 3-5, the white blobs started releasing themselves from the smoother surfaces (walls, floors, etc.)
5 days later, I have a crystal clear pool. We spent the first 2 days cleaning the skimmers and pump basket HOURLY to get the globs of **** that came loose and were gumming it up. We brush the sides 4 times daily.
The problem? It's still growing, but not as bad as it was. It no longer grows on the walls or angular surfaces. I'm finding it growing small masses of jellyfish-looking white material attached to the skimmer gaskets, the light niche ring, and the strips where the vinyl liner attaches to the fiberglass steps. This despite a very high borate level (~100 ppm or so) and high Cl level (~20 ppm or so). And it's not in low-circulation areas - inside the skimmers, it's growing where water is circulating all the time.
TC > 10 ppm (test strips go to 10)
FC ~ 20 ppm
As I understand, the standard treatment for tough pink slime / white water mold is to use high borate levels to break the biofilm apart, and high chlorine levels to kill the bacteria. I would think my current levels would preclude the growth.
At this point, the pool is closed to swimmers.
My next steps are to try a specific algaecide marketed by a company for the "pink" algae, and/or use a high dose of algaecide, but before that I wanted to reach out here for any suggestions.