Hello: Question about Water Mold/Pink Slime

[ghostcat]

Hi. I am in NJ. I have an inground pool. 31,000 gallons, Hayward Sand Filter, Automatic Chlorinator, Aqua Comfort Heat Pump. I had water mold on my ladder, light, steps etc and fought it last year. This season there was no sign of it until last Saturday. I scrubbed, removed steps, and vacuumed on waste. I also backwashed the filter very well. I have been keeping the free chlorine at 5 for the whole season. I shocked last Saturday night with liquid shock. There has been no sign of it since last Saturday. I am closing the pool on September 14th. 2 weeks! What level of chlorine should I keep it away until I close?
Current readings(today) with a Taylor K-2006:
FC 7.5
CC 0
Ph 7.4
ALK 90
CYA 130 (High) Chlorinator is at 1
CH 230
I am using liquid shock 12.5% Sodium hypochlorite and scrubbing everyday..
This weekend is Labor day and the kids want to swim. I want to avoid the pink slimy water mold but let them swim this weekend. Any suggestions? Thanks in advance...

[ghostcat]

Forgot to add...Concrete pool with vinyl liner and running the filter 22 hours a day..Thanks...

[aylad]

For a CYA that high, your chlorine needs to stay in the 8-15 ppm range. I personally would keep it closer to 10 ppm, to allow yourself a little wiggle-room, but you don't want it drop drop below 8 ppm at all.

If your water is clear, and unless you need it for the heat pump, you don't really need to run the filter for that long everyday unless you just want to--you'd save yourself some $$ on the electric bill if you cut it back to 10-12 hours/day, and even that is excessive for some pools......

[ghostcat]

Thank you very much. I will follow your advice.