SLAM

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DBarry

Member
May 2, 2025
15
Easton, MA
Pool Size
42500
Surface
Plaster
Chlorine
Liquid Chlorine
Hello again!

I started the SLAM process yesterday, added 17 gallons of liquid chlorine and this morning my FC is still reading 0.5. Pool math keeps having me add 4.5 gallons each time. (About every 2 hours)

I am very new to this, but that sounds like a lot of chlorine for no movement in results.
1. Is that normal?

2. I understand too that this process can take days, does the filter need to run 24/7 for the entirety of the SLAM process?

3. My goal is 12. How long does it have to maintain that level? Or are we just looking for the -1 loss overnight (plus the other two criteria) and then I can bring the FC back down to the desired level based on my CYA.

43000gal gunite
pH 7.4
TA 80
Calcium 350
CYA testing had mild blurring initially, so I was instructed to measure this as 10 and add in CYA for a goal of 30, which I did prior to SLAMMing
 
1: Not unusual, but not normal. Sounds very much like an ammonia issue, which sometimes happens over the winter. If the FC drops to zero then a common water bacteria may get in the water and begin consuming the CYA and excreting ammonia. This needs to be cleared out with chlorine as well as killing off the bacteria causing the issue.

Getting Rid of Ammonia in Pool Water​


  1. Dose the pool to a SLAM level of 10 ppm
  2. Do not add any CYA until chlorine begins to hold
  3. Test chlorine every 30 minutes until chlorine begins to hold. Add chlorine as needed to get back to 10 ppm. FC will likely test close to 0 until you get to the next step
  4. You will know when the chlorine begins to hold when you see FC testing > 3 ppm after 30 minutes.
  5. When you see a significant jump in FC from the prior 30-minute test CYA can be added back into the pool. Limit the CYA to 30 ppm for the duration of the process
  6. Increase the FC target to 12 ppm and follow the steps in the SLAM Process until the criteria of “Done” are all met.
  7. Follow the SLAM Process FC test procedures. You no longer need to test every 30 minutes at this stage.
Click to expand...
When you get to step 5 you should re-test your CYA in case there was any of the CYA eating bacteria in the water when you added the batch. Bring it back to 30 ppm if it is reading below that.

2: Yes, you want water to circulate well through the pool and full filtration during the process.

3: Once you complete the process above the drop should be much less severe between tests.
 
Also, have you checked the date code on your liquid chlorine to make sure it is fresh? Liquid chlorire starts to degrade and if its really old, those 17 gallons added could have been mostly water.
 
Donldson said:
1: Not unusual, but not normal. Sounds very much like an ammonia issue, which sometimes happens over the winter. If the FC drops to zero then a common water bacteria may get in the water and begin consuming the CYA and excreting ammonia. This needs to be cleared out with chlorine as well as killing off the bacteria causing the issue.


When you get to step 5 you should re-test your CYA in case there was any of the CYA eating bacteria in the water when you added the batch. Bring it back to 30 ppm if it is reading below that.

2: Yes, you want water to circulate well through the pool and full filtration during the process.

3: Once you complete the process above the drop should be much less severe between tests.
Click to expand...
I am on step 4 right now. I added in 4.25 gallons initially and 30minutes later FC is now 1.5. I just added another 3.5 gallons.

When it says FC is holding when it’s >3, does that mean my next reading should be higher than 3 or does it mean 3 higher than my 1.5 result (4.5)?
 

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Still at 2.5, this is so discouraging ! Lowe’s is going to ban me for a suspicious amount of buying activity :LOL:

Can anyone provide reassurance that I’m doing the right thing still? I’ve gone through 28 gallons today …
 
DBarry said:
Can anyone provide reassurance that I’m doing the right thing still? I’ve gone through 28 gallons today
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You are doing great !!! Ammonia is nasty stuff. I'd go with 30 min tests/adds if possible.

Use no UV burnoff to your advantage in the late afternoon and later. With no CYA you probably lost a bunch of FC to the sun.
 
Newdude said:
You are doing great !!! Ammonia is nasty stuff. I'd go with 30 min tests/adds if possible.

Use no UV burnoff to your advantage in the late afternoon and later. With no CYA you probably lost a bunch of FC to the sun.
Click to expand...
Thank you both!!! Been doing 30 min all day long - as close to it as possible with 3 kids!

Trying to get to 3ppm before bed so I can use the CYA tonight. If not, will I be back to zero in the morning!?

Curious to know why the chlorine amount between adds isn’t increasing when I’m getting the same results. Is this so we don’t eventually overload it with chlorine once the bacteria and ammonia are destroyed?
 
DBarry said:
Been doing 30 min all day long - as close to it as possible with 3 kids!
Click to expand...
OK awesome. Do the best you can. We all have life in the way. We get it.
DBarry said:
Trying to get to 3ppm before bed so I can use the CYA tonight. If not, will I be back to zero in the morning!?
Click to expand...
If you get there, you get there. If not, progress is still progress.
DBarry said:
Is this so we don’t eventually overload it with chlorine once the bacteria and ammonia are destroyed?
Click to expand...
Yes, but before that point, chlorine is harsh on the pool and equipment with no CYA to buffer it, even only for the few minutes before it depletes. It would seem to make sense to just nuke the ammonia, but a slow and steady controlled burn has proven safe and effective many many times. Unfortunately, it takes time at 10 FC to 0, 10 to 0, 10 to 0, repeat lather rinse........
 

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