I have a few questions about the optimal FC/CYA ratio when adding polyquat at closing. It says on here to add it at 1/2 SLAM level so FC/CYA ratio is 20%. I did that the last time that I used Polyquat with a CYA of 40 and the polyquat lowered the FC from 8 ppms to 4 ppms so FC was barely above minimum FC level. If you are using polyquat when the water temperature is 62 degrees, have a mesh cover, and have mild winters, would it help prevent algae better if it was added at 2 ppms above 1/2 SLAM level so the FC might be a bit higher? Or is polyquat more effective if it is added at 1/2 SLAM level so FC/CYA ratio is 20%? I skipped the polyquat last year and opened up to dark green water so I don’t want to skip it this year.
FC/CYA ratio when using polyquat at closing
- Thread starter al27
- Start date
- Jun 24, 2021
- 15,883
- Pool Size
- 29000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
1/2 slam is 1/2 way between normal FC and SLAM level. Assuming your CYA is 40, 1/2 slam would be half way between 7 and 16...or about 11-12 FC. At 50 CYA that would be 1/2 way between 8 and 20...or 14 FC.
Get the pool to 1/2 slam as described above, add the polyquat, circulate for 24 hours and close. Good to go!
Get the pool to 1/2 slam as described above, add the polyquat, circulate for 24 hours and close. Good to go!
The algaecide directions on “pool school” say to add it at 1/2 slam level so the FC/CYA is 20%. If it is supposed to be added at halfway between normal FC and SLAM level, someone might want to change this on pool school so the directions are more clear because halfway between normal FC and full SLAM level is much higher than a FC/CYA ratio of 20%.
- Jun 24, 2021
- 15,883
- Pool Size
- 29000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Can you post a link to the algaecide directions so I can resolve?
As for closing,
SLAM – Two or three days before closing, I bring the pool up to shock level and hold it there until FC holds overnight (which it generally does right off on the first night). Then I let the chlorine level fall about half way back to normal levels, typically another day and a half.
From here:
www.troublefreepool.com
As for closing,
SLAM – Two or three days before closing, I bring the pool up to shock level and hold it there until FC holds overnight (which it generally does right off on the first night). Then I let the chlorine level fall about half way back to normal levels, typically another day and a half.
From here:
Closing an In Ground Pool
Winterizing a pool is essential for keeping your in-ground pool protected during cold-weather months. This Pool Repair guide will show you how to do it.
www.troublefreepool.com
1/2 SLAM is 1/2 way between 0 and SLAM or a FC/CYA of 20%.
- Jun 24, 2021
- 15,883
- Pool Size
- 29000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
- Jul 21, 2013
- 65,062
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
To phrase it another way, any FC level between normal FC and 1/2 SLAM level (20% of CYA) is ok for adding Polyquat 60. The specific value does not matter.
Thanks for clarifying this. Two years ago when I added the polyquat at 1/2 SLAM (20% of CYA), it lowered my FC from 8 ppms to 4 ppms. 4 ppms is only 1 ppms above the minimum FC for a CYA of 40. If you are adding the polyquat when the water temperature isn’t quite below 60 yet, would it be beneficial to add the polyquat at 2 ppms above 1/2 SLAM so the FC is 3 ppms above the minimum CYA level? We’ve been having a heat wave here so my water isn’t going to be below 60 when a pool company closes it on Friday. The water temperature is hovering around 62-63 degrees and it probably won’t drop below 60 for another week. Im just wondering if it might help if I added the polyquat at slightly above 1/2 SLAM so there is more residual chlorine left or if I would likely have better results at just adding it at 1/2 SLAM. I’ve got a mesh cover that is probably 20 years old so it doesn’t do a very good job at blocking out the sun.
- Jul 21, 2013
- 65,062
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
The minimum FC level does not apply when you have chlorine and Polyquat in the pool.
Too much chlorine will undo the polyquat.
You are fine the way you are doing it.
Too much chlorine will undo the polyquat.
You are fine the way you are doing it.