SLAM sanity check

[AW139]

Been maintaining my pool for a couple years, using the TFP method. So far so good.

Last year I opened to a crystal clear pool with 7.4 pH and even a trace of FC left. This year I opened to a green pool, pH around 6.8 and no FC obviously. Got the pH up, and stared the SLAM process. In about 3 days the water was decently clear, and was losing around 3 ppm FC overnight. Vacuumed out all the dead algae, cleaned the filter. So far so good. A couple days later the water is crystal clear, less than 0.5 CC (started at 1.5-2.0 CC), but still burning through the liquid chlorine. It’s been a week and still no end in sight. I top up to 24 ppm FC, and 4 hours later I’m down to 20. I’m still burning like 20 FC a day.

In the past I have SLAMed for minor issues, but didn’t take more than a couple days. Is it typical to take longer than a week even after the water has cleared to finish?

Number from before starting the SLAM:

8.0 FC
7.2 pH
60 TA
280 CH
60 CYA
1200 SALT

 

[PoolStored]

Have you done ALL of these:

• Brush the entire pool once a day if you can. Brush inside skimmers, under main drain covers, on weir doors, inside ladders, and behind removable lights if applicable.

 

[AW139]

Have you done ALL of these:

• Brush the entire pool once a day if you can. Brush inside skimmers, under main drain covers, on weir doors, inside ladders, and behind removable lights if applicable.

Yup. Brushed the pool pretty extensively a number of times. It’s a pretty basic fibreglass pool with no ladders, so not too many nooks and crannies for algae to hide in. Substantial algae came off the walls the first brushing, but nothing visible after that. Vacuumed a few times too.

 

[PoolStored]

Check weir doors for algae.

 

[AW139]

Check weir doors for algae.

I'll take a peak. I removed it for winterization so I don't suspect it will have any algae, but I can't be sure.

 

[AW139]

From 8am till 3pm today I burned through 10 ppm FC.

I’m still at a loss. Inspected and cleaned/brushed every accessible surface that touches the water. Cleaned the filter (it was very clean), and I’m still burning through chlorine like it’s going out of style. Combined Chlorine is at 0.0 with not even a hint of pink when adding R-0003. Double checked my CYA levels, and it’s at the expected 60 ish ppm.

I’m going to just continue maintaining 24 ppm FC for the next few days and hope this is near the end. It just feels like I’m missing something here.

 

[Newdude]

Do an unofficial OCLT at whatever is convenient times. If there is some daylight on either end it wont account for much, but will give you an idea about how much was lost to UV.

Was the CYA test today with overhead sun ? If its not bright enough you'll lose the dot early and think its 60 when its 20.

 

[AW139]

Do an unofficial OCLT at whatever is convenient times. If there is some daylight on either end it wont account for much, but will give you an idea about how much was lost to UV.

Was the CYA test today with overhead sun ? If its not bright enough you'll lose the dot early and think its 60 when its 20.

OCLT will unfortunately have to wait a few days (yay EMS nigh shifts), but that’s first on my list when I can. I’m happy to see the CCs at zero, at least that’s progress.

I have done the CYA test a couple times this year in different lighting conditions with identical results. Dot visible at 60, gone by 50. It tracks with my closing numbers from last year.

 

[Newdude]

. It tracks with my closing numbers from last year.

How so ? We lose 3 to 5 ppm a month which isnt noticable during the season, but is definitely noticable when you walk away from the pool for 7 or 8 months. (Maybe even 9 up by you. )

Thats with a solid cover / tarp. With a mesh cover the rain and melted snow wipe most of us out by opening.

So if you closed with 30 or more CYA and now its down to 60, then it tracks, but its suspicious if you closed and opened at 60.

 

[AW139]

How so ? We lose 3 to 5 ppm a month which isnt noticable during the season, but is definitely noticable when you walk away from the pool for 7 or 8 months. (Maybe even 9 up by you. )

Thats with a solid cover / tarp. With a mesh cover the rain and melted snow wipe most of us out by opening.

So if you closed with 30 or more CYA and now its down to 60, then it tracks, but its suspicious if you closed and opened at 60.

Interesting. I don’t get any real reduction of CYA over the summer. Certainly not 5 ppm a month. The test visually looks exactly as it did when I closed, which if atypical means either I’m testing incorrectly or for whatever reason my pool doesn’t lose CYA very much. The pool was closed for 6 months this winter.

 

[Newdude]

either I’m testing incorrectly or for whatever reason my pool doesn’t lose CYA very much.

If you were testing incorrectly you'd be consistently incorrect and you'd still see the reduction. For example you thought it was a 60 when it was an 80. If it dropped to 20, you'd think it was 40.

So its more likey your CYA holds unusually well.

Stay the course the best you can and get us an OCLT when possible.