SLAMing and not holding chlorine

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leahhobday

New member
Apr 11, 2025
4
cincinnati ohio
Help me understand chlorine. We opened our pool last week. Pretty quickly it went from green to a teal color and our pool store (we love them and they aren’t trying to sell extra chemicals) said that is the dead algae. It’s 30k gallon chlorine pool with a vinyl liner. When we opened we dumped in 8 gallons of liquid shock and algaecide. Fast forward and we have been dumping 4 gallons every day since and it’s not holding chlorine. Our cya is 30. Our ph and alkalinity are both in the normal range and so is our hardness. There are no phosphates. On Tuesday we decided to add floc to get rid of the cloudiness. We’ve been letting it rest since then (2 days). It got a little bit clearer and we could see the ground in the shallow end and barely in the deep end. But, because it was sitting for two days a little algae is starting to grow. Then I discovered pool math and I followed pool math and slammed it with thr powder chlorine. I added 5 bags (per the app recommendation) and two hours later I tested it and the free chlorine is still at 1ppm. I just added 5 more bags. What else can I be doing to help this pool hold chlorine? It’s driving me nuts. 🤣🤣🤣🤣
 
Welcome to TFP! :wave: Several things you noted are contradictory to TFP philosophy and how we treat/manage algae, so I'll lay it out as clear as I can:
- Algae can only be killed by applying the correct free chlorine-to-stabilizer ratio (FC-CYA) as noted on the FC/CYA Levels. I can just about guarantee you that your local store is not equipment to test FC at these levels, and certainly not going to test your water 2-3 times as day to ensure that elevated FC level is maintained. If you don't have your own TF-100/Pro Series test kit or Taylor K-2006C, that must be step #1.
- To kill algae, we use the SLAM Process. It works when followed properly, but you must have on one of those test kits.
- Floc does not kill algae and can most certainly complicate your pool situation by compromising the filter media. We almost never recommend floc or clarifies.

It all boils down to the proper test kit and the SLAM Process. Take a few moments to look that link over and let us know f you have more questions.
 
These links may also help you.

www.troublefreepool.com

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why shouldn't I use test strips? Our recommended test kits will pay for themselves in no time!
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Test Kits

tftestkits.net tftestkits.net
 
Hello,

What are you using to test with? You need your own TFTPRO TEST KIT, don't rely on the pool store results. Vets here will ask you to share these test results:

FC:
CC:
PH:
TA:
CH:
CYA:

At 30k gallons your CYA is low which is why your pool is not holding on to chlorine. However don't add anything else until you share these test results from a dependable test kit. The previous advice should be followed. It sounds like you will need to SLAM, OCLT, brush, vac, add liquid chlorine, and get that cya in a range that will hold your chlorine, otherwise you'll continue doing what you're currently doing and seeing what you're seeing. I'll let more seasoned folks give you the details though. 😊
 
Texas Splash said:
Welcome to TFP! :wave: Several things you noted are contradictory to TFP philosophy and how we treat/manage algae, so I'll lay it out as clear as I can:
- Algae can only be killed by applying the correct free chlorine-to-stabilizer ratio (FC-CYA) as noted on the FC/CYA Levels. I can just about guarantee you that your local store is not equipment to test FC at these levels, and certainly not going to test your water 2-3 times as day to ensure that elevated FC level is maintained. If you don't have your own TF-100/Pro Series test kit or Taylor K-2006C, that must be step #1.
- To kill algae, we use the SLAM Process. It works when followed properly, but you must have on one of those test kits.
- Floc does not kill algae and can most certainly complicate your pool situation by compromising the filter media. We almost never recommend floc or clarifies.

It all boils down to the proper test kit and the SLAM Process. Take a few moments to look that link over and let us know f you have more questions.
Click to expand...
We have a home test kit (Taylor k 2006c) that I’ve been testing every two hours today at home. We just started the slam process today because I just learned about it.
 
elleb said:
Hello,

What are you using to test with? You need your own TFTPRO TEST KIT, don't rely on the pool store results. Vets here will ask you to share these test results:

FC:
CC:
PH:
TA:
CH:
CYA:

At 30k gallons your CYA is low which is why your pool is not holding on to chlorine. However don't add anything else until you share these test results from a dependable test kit. The previous advice should be followed. It sounds like you will need to SLAM, OCLT, brush, vac, add liquid chlorine, and get that cya in a range that will hold your chlorine, otherwise you'll continue doing what you're currently doing and seeing what you're seeing. I'll let more seasoned folks give you the details though. 😊
Click to expand...
leahhobday said:
We have a home test kit (Taylor k 2006c) that I’ve been testing every two hours today at home. We just started the slam process today because I just learned about it.
Click to expand...
I just tested again (1 hour after adding the second addition of shock today)

Free chkorine is 8
Ph is 7.4
Alkalinity is 120
Cya is 30
Hardness is 200.
 
Only FC matters now, skip the others. Maintain it at 12 (per your 30 CYA) as often as it dips. As the process plays out, it holds longer and longer between doses.

IMG_2607.jpeg
 
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Powdered products for chlorine add additional CYA or calcium to your pool alsong with the chlorine. I would perform a complete panel of tests again if you havent yet, just to make sure you are using the latest values for each level (particularly CYA, Calcium)

Liquid chlorine is always preferable.
 
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