I'm in the process of SLAMing a friends pool. The pool is a 1970's vintage. It has a skimmer and main drain and 2 return eyes. There is an attached spa with a separate drain and 5 return eyes.
My trouble is the cya is running at 60 giving a shock value of 24 (28000 gallon). I dosed the pool to FC=27 after dark last night. This morning around 8 am it had dropped to 15 so we added 4 jugs of 8.25% bleach. The next reading a couple hours later read 30. This is higher than I expected. A subsequent reading gave an even higher result, 40, without adding more bleach.
I don't think I'm doing anything wrong but I'm confused by these readings. I suspect the pool is not mixing well due to only 2 returns. I also question whether the filter is filtering well because when I vacuumed this morning the pool clouded up pretty quick.
I have a related post in the Pumping Station forum. I hope to do a deep clean on the filter pending more info about the filter.
The readings so far
Last FC 40
CC not read
CYA 60 (after dumping water, was 100, didn't get as low as hoped)