SWG Chlorine Output Troubleshooting Help Needed

[Mm314297]

Hey Everyone,

This is our 2nd year with our in-ground vinyl pool (bought the house last year), and TFP helped me a TON last year! This year I was off to a good start again, however, it seems like our SWG is not producing the same amount of chlorine as it did last year with the same settings. Last year I was able to run the pool pump for about 4 hours a day with SWG set to around 40-50% and it had no issues producing enough. This year I have had to run the pump 6 hours a day with SWG set to 80% and it still doesn't seem like it is keeping up.

About a week ago we did have a very slightly cloudy pool when FC dropped below minimum for about a day before I realized something was up with SWG. I quickly brought it up to about half SLAM level and it cleared right up. My initial thought was that maybe even though I thought I had killed all the algae that there might be some residual Algae using up the FC as fast as the SWG could use it, so I did a OCLT last night, but it passed. I'm not sure what to do at this point. I know Salt Cells are about a 5 year life span, and this one looks kind of old, but there is no serial number on it for me to figure out the year of MFG. we currently are a turbocell 9, which is rated for 25k pools (We have about 18,000), and I saw somewhere on here that you guys recommend a cell that is 2x or more for your pool size, so do I need to upgrade to a turbocell 15? Any help with troubleshooting or recommendations would be awesome.

OCLT:
Saturday Evening 6/20/20
FC = 8
CC = 0.5 (Did a bunch of swimming during the day)

Sunday Morning 6/21/20
FC = 8
CC = <0.5

Full test results Sunday Morning 6/21/20
FC = 8
CC = <0.5
pH = 7.5
CH = 125
ALY = 70
Cya = 70 - 80 (Always have a hard time judging on this test, but it's definitely at least 70)
Salt = 2800 (I know this is a little low at the moment, but it is above the minimum for my SWG, I will add some today. Also this low amount of FC problem was still an issue when Salt was at 3200+)

 

[mknauss]

It is pretty hard to believe your pool was consuming only 0.8 ppm FC per day last year. Do you keep it covered? No sun, no swimmers?

Your settings this year at 1.2 ppm FC being added each day. Still very low.

If you pass OCLT and the water is clear, I would raise the generation level to 3 ppm FC per day and see if the SWCG maintains the FC level you need for your CYA. That would be 100% generation setting for 12 hours per day.

 

[Mm314297]

Yeah I'm not sure I guess about last year, but I'm pretty positive my pump run time and SWG were that low, which is also where they still were when I opened the pool this year.

I will try your suggestion and see what happens. It seems like 12 hours at 100% is working the cell pretty hard. Is my cell undersized for my pool then?

*Edit* forgot to answer about sun. Pool stays uncovered, has part sun for about 4 hours per day, and full sun around 5 hours per day. Only typically 1-2 swimmers unless we have people over

 

[mknauss]

A T9 is rated for a 25K pool. Your pool is 19K. So yes, your SWCG is small based on our recommendation to have the SWCG rated for at least 2X pool volume.

 

[Jimrahbe]

Mm,

I show that your SWCG, in your pool, should generate about .24 ppm of Chlorine per hour at 100% output.. or 5.8 ppm per 24 hours.

So 6 hours at 80% is only 1.15 ppm of FC... Since most pools use 2 to 4 ppm per day that is dreadfully low.

Thanks,

Jim R.

 

[Mm314297]

I must be mis-remembering something about last year then. I will switch settings to 100% for 12 hour run time and go from there. Once this cell eventually fails I'll look at upgrading to a turbocell 15. Thanks for the help!

 

[revitup]

Our SWG keeps up producing between 1.1 - 1.7 PPM per day so I don't find the OPs use level so out of line. We get 8 or 9 hours of sun and typically only 1 - 2 swimmers (adults) per day.