Pool opening SLAM

[Mam262]

Hello,

Thank you for all that everyone does here, it has been so very helpful. This is my 3rd pool opening. I seem to really struggle with my opening SLAM each year. I open early when air temps are in 50's - 60's and water temps are in 50's.

My question is regarding my opening SLAM as my FC loss keeps fluctuating.

30,000 gallon SWG gunite pool. Live in Southeastern, PA and opened my pool 4/19. Water was clear with usual debris as expected. Pump has been running 24/7 and all debris vacuumed out. Have been brushing daily. Air temps have been between mid-30's and mid-50's. Water temp is currently 51.

Last year I dealt with what I thought was ammonia upon opening, so I had to get my FC really high.

Upon opening my results were:
FC: 0 CC 0.5
PH: 9
TA: 40
CH: 275
CY: 20

Before starting SLAM on 4/20 I adjusted PH to 7.2 and
TA: 50
CH: 375
CYA 30

Starting night of 4/20 I have been using liquid chlorine 10% and 1lb bags of cal-hypo to SLAM, testing every 3 hours other than overnight and adding FC frequently,

Here is my log starting 4/21. In call cases CC is 0.5

4/21
6:00am FC 17.5
6:00am add 5.9
9:45am FC 17
10:00am add 9.2
12:30pm FC 24
12:45pm add 3.3
4:00pm FC 21
4:30pm add 5.9
7:30pm FC 23
9:00pm add 5.9

4/22
6:00am FC 30
10:30am FC 18
10:30am add 5.9
1:30pm FC 23.5
5:15pm FC 15.5
5:15pm add 5.9
8:45pm add 8.5
10:30 FC 31

4/23
6:30 FC 28

Water has been crystal clear since the morning of 4/22.

There are periods where the FC seems to hold and others where it drops. For instance it held overnight 4/21 - 4/22. But then it dropped significantly morning of 4/22 from 30 to 18 in 4.5 hours then again from 23.5 to 15.5 in another 4 hour period. Last night it went from 31 - 28. I realize my FC is really high but I am trying to push through this SLAM as quickly as possible.

Should I consider that holding or dropping?

I welcome all thoughts, suggestions and even criticisms!!

 

[Texas Splash]

"Mam", I would continue the SLAM Process, but definitely let the FC drop to the proper FC level of "12" which is based on your current CYA of 30. See FC/CYA Levels. The problem with going too high, in your case 2Xs the SLAM level, is that there is not enough correlating stabilizer to support the chlorine. Therefore it will drop quickly and you'll see some erratic testing behavior. So maintain the FC of 12 and continue with the SLAM protocol. Hopefully testing will look much more stable. Let us know if you ave any questions.

 

[Mam262]

"Mam", I would continue the SLAM Process, but definitely let the FC drop to the proper FC level of "12" which is based on your current CYA of 30. See FC/CYA Levels. The problem with going too high, in your case 2Xs the SLAM level, is that there is not enough correlating stabilizer to support the chlorine. Therefore it will drop quickly and you'll see some erratic testing behavior. So maintain the FC of 12 and continue with the SLAM protocol. Hopefully testing will look much more stable. Let us know if you ave any questions.

Thank you. I do have a question. Even though it has been cloudy and cool this week, the FC would still burn off during the day if not enough CYA to support it? I thought that would only occur in hot/sunny weather.

Mike

 

[Texas Splash]

I do have a question. Even though it has been cloudy and cool this week, the FC would still burn off during the day if not enough CYA to support it? I thought that would only occur in hot/sunny weather.

That's a reasonable assumption sure. The FC consumption rate varies on several factors, some of which you noted, and others that probably get a little deeper (chemistry) than I can even explain. One of those molecule discussions that hurt my head. But I do know from my own younger TFP days during my first SLAM, speaking to one of our founding chemists who told me, if I overshoot my SLAM level by too much, the FC will be unpredictable and fluctuate, potentially resulting in a failed OCLT or other odd testing behavior. This is one of those cases where more is not better.

 

[Mam262]

That's a reasonable assumption sure. The FC consumption rate varies on several factors, some of which you noted, and others that probably get a little deeper (chemistry) than I can even explain. One of those molecule discussions that hurt my head. But I do know from my own younger TFP days during my first SLAM, speaking to one of our founding chemists who told me, if I overshoot my SLAM level by too much, the FC will be unpredictable and fluctuate, potentially resulting in a failed OCLT or other odd testing behavior. This is one of those cases where more is not better.

Thank you very much. I really appreciate it. I will put this statement in my notebook: "if I overshoot my SLAM level by too much, the FC will be unpredictable and fluctuate, potentially resulting in a failed OCLT or other odd testing behavior. This is one of those cases where more is not better."

Thanks again!!!!

 

[Casey]

It's also a huge waste in chlorine.