FC level borderline low despite balanced water and high SWG %

[jeffblue]

Hi all, having a strange issue. i'm seemingly unable to get my chlorine above 5ppm. It is consistently staying between 4 and 5ppm which is on the low side for 80-90CYA. I'm running the pump 8 hours per day at 87% duty cycle (which seems high to me just to be maintaining FC of 5. the cell is appropriately sized for the pool. i suspect it is caused by 1 of 3 things but would love some input.

1. is it possibly that my ph is on the low side so chlorine is oxidizing?
2. is it that my cell is just dying? its a few years old.
3. is it just maybe that if i'm only running the pump 8 hours per day that i will need it cranked this high. last year i do remember keeping it lower 60% or so, with a lower CYA (60-70) and i'd run into situations if i left my solar blanket on a day here and there the FC would rise significantly. i was also running higher salt last year, about 3500ppm.
4. is it because maybe with my CYA being high, my chlorine dipped too low at one point and now i have an algae issue that i dont realize is there? CC is 0 though and water is clear.

pH: 7.2
FC: 4-5 (9 drops with 10ml dpd test)
CC: 0
CYA: 80-90
TA: 70
Borates: 50ppm
salt: 3200

Thanks!

 

[Texas Splash]

I would rule-out #1 as having any significance. But the others are certainly possible. Even #2 as I believe SWGs have a typical service life of about 5 years or so. But you left-off one other possibility .... a dirty (scale) SWG. Have you cleaned it (plates) recently? Just a thought. Either way, that is some TFP-perfect looking water. Very nice.

 

[jeffblue]

I would rule-out #1 as having any significance. But the others are certainly possible. Even #2 as I believe SWGs have a typical service life of about 5 years or so. But you left-off one other possibility .... a dirty (scale) SWG. Have you cleaned it (plates) recently?

I did rinse it out after i cleaned out my filter from my first slam before adding CYA, but i didn't use acid. i'll try that. hopefully i don't burn it out having it cranked like this and hopefully it can maintain at least 5ppm until i can get this sorted out. i really dont want to have deal with partial drain/replace to lower CYA and then slam. This might be the original cell that the original homeowner purchased when the pool was built in 2011, so it might just be dying. not looking forward to buying another one if that's the case:thumbdown:

Either way, that is some TFP-perfect looking water. Very nice.

Thanks! TFP ftw! this year was my second pool opening, it was such a breeze. water was clear in no time