High PH, Low Alkalinity - need to SLAM

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H

harrell_ashley

Member
May 24, 2022
20
mississippi
Pool Size
24000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hello,
New to pool maintenance, and I am at a loss. We've had service techs out, but our pool is still green. PH is 8.4 and Total Alkalinity is 40. I think I need to lower the Ph before I start the SLAM process. We have a 24,000 gallon in-ground pool with a filter, chlorine pool. I need some step by step instructions. I've watched the SLAM youtube videos, but with my PH being high and Alkalinity being low, I do not know what I need to do first. Muriatic acid to lower PH? Then once PH is lowered, how much shock do I need? Or what kind of liquid chlorine do I need? Can I use Clorox bleach? I've had pool techs working on this for about two weeks now, and it's still just as green as when we started. They are great, but I really think we need to SLAM.
Thank you, ARH
 
Welcome to TFP!!

How are you testing your water? To be able to proceed with an effective SLAM you are going to need a reliable test kit. Either a TF-100 (link on my signature) or a K-2006C. See Test Kits Compared

harrell_ashley said:
Can I use Clorox bleach?
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You can use unscented, non-splashless, no additives household Bleach. Clorox has additives.

Don't worry, we will help you to get your pool TFP clear.
 
I'm no chemist, but I have the Taylor K-2006c kit and HTH test strips. I've been comparing the two. The Ph is purple with the test kit, which I read is 8.4, and when I added the drops (not sure what drops they were at the moment) to measure alkalinity and multiplied that by the number of drops I used, I got the 4 drops x 10 = 40.
 
harrell_ashley said:
I'm no chemist, but I have the Taylor K-2006c kit and HTH test strips. I've been comparing the two. The Ph is purple with the test kit, which I read is 8.4, and when I added the drops (not sure what drops they were at the moment) to measure alkalinity and multiplied that by the number of drops I used, I got the 4 drops x 10 = 40.
Click to expand...
We call them guess strips around here :)
As long are you are not squeezing reagents bottles any more than a very gentle squeeze and you are counting the drop correctly I trust your test.
Check if this helps: TF-100 kit quick reference guide testing instructions
 
I would add baking soda to get TA up to 60 or so, then muriatic acid to bring down the pH. This will lower your TA, but baking soda increases TA with a small increase in pH, so going to about 60 looks like a good spot to end up about 50 TA once the pH is lowered.

Add 113oz by weight of baking soda (about 7 lbs) - increase of pH by .04 and raises TA by about 20.
Add 48oz of 20 baume MA (31.45%) - decrease pH to 7.2, lowers TA by about 10.

The baking soda is pretty safe to add first without doing a partial add, but I would probably only add half the MA I put above and re-test pH to see if it dropped the expected amount. I used 24000 gal but you could be off on that by a bit (not unheard of) and don't want to crater your pH by adding too much acid.

Can you post the full test results from the K-2006c? Advice on next steps will depend on the remainder of the test results.
 
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IceShadow said:
I would add baking soda to get TA up to 60 or so, then muriatic acid to bring down the pH. This will lower your TA, but baking soda increases TA with a small increase in pH, so going to about 60 looks like a good spot to end up about 50 TA once the pH is lowered.

Add 113oz by weight of baking soda (about 7 lbs) - increase of pH by .04 and raises TA by about 20.
Add 48oz of 20 baume MA (31.45%) - decrease pH to 7.2, lowers TA by about 10.

The baking soda is pretty safe to add first without doing a partial add, but I would probably only add half the MA I put above and re-test pH to see if it dropped the expected amount. I used 24000 gal but you could be off on that by a bit (not unheard of) and don't want to crater your pH by adding too much acid.

Can you post the full test results from the K-2006c? Advice on next steps will depend on the remainder of the test results.
Click to expand...
I only tested the Ph, alkalinity and the CYA using the test kit. CYA was 0! I filled that tube all the way up and could still see that little black dot. Using the strips, my readings are: Total Hardness - 250; Total Chlorine - 0; Free Chlorine - 1; PH - 8.4; Total Alkalinity - 40; Stabilizer - 100. Did I mention the pool is green. Vacuumed to waste and it is coming out just as green as it looks in the pool. It's safe to put both the baking soda and the MA in back to back?
 
harrell_ashley said:
I only tested the Ph, alkalinity and the CYA using the test kit. CYA was 0! I filled that tube all the way up and could still see that little black dot. Using the strips, my readings are: Total Hardness - 250; Total Chlorine - 0; Free Chlorine - 1; PH - 8.4; Total Alkalinity - 40; Stabilizer - 100. Did I mention the pool is green. Vacuumed to waste and it is coming out just as green as it looks in the pool. It's safe to put both the baking soda and the MA in back to back?
Click to expand...
I would add the baking soda at one return jet, wait about 15-20 minutes with the pump running, then add acid to a different return jet. My thinking is you want the TA increased first so you don't have the acid working in a localized spot that's concentrated in baking soda. After another 15-20 minutes after the acid is added, test TA and pH again. Add rest of acid if necessary. The TA test isn't exact, so you might end up needing a bit more baking soda too. You want the TA at 50 or above and the pH at 7.2 before you SLAM.

However, with 0 CYA and 0 FC and a green pool, you'll want to check first to make sure you don't have ammonia (and the bacteria that eats CYA and makes ammonia) in your pool.

- Add 10ppm of FC to the pool with liquid chlorine / bleach / liquid shock / etc. (all the same thing, just different concentrations)
- Let pump mix for 10 minutes
- Measure FC. See if it is still holding any FC at all.

You can do this before or after you mess with the acid and the baking soda. Just don't add the MA and the liquid chlorine at the same time as that can make not good fumes. Let us know if it is still holding FC and we can work from there!
 
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IceShadow said:
I would add the baking soda at one return jet, wait about 15-20 minutes with the pump running, then add acid to a different return jet. My thinking is you want the TA increased first so you don't have the acid working in a localized spot that's concentrated in baking soda. After another 15-20 minutes after the acid is added, test TA and pH again. Add rest of acid if necessary. The TA test isn't exact, so you might end up needing a bit more baking soda too. You want the TA at 50 or above and the pH at 7.2 before you SLAM.

However, with 0 CYA and 0 FC and a green pool, you'll want to check first to make sure you don't have ammonia (and the bacteria that eats CYA and makes ammonia) in your pool.

- Add 10ppm of FC to the pool with liquid chlorine / bleach / liquid shock / etc. (all the same thing, just different concentrations)
- Let pump mix for 10 minutes
- Measure FC. See if it is still holding any FC at all.

You can do this before or after you mess with the acid and the baking soda. Just don't add the MA and the liquid chlorine at the same time as that can make not good fumes. Let us know if it is still holding FC and we can work from there!
Click to expand...
It has since rained and now I’m testing again.
I used the Taylor k2006c. Got my sample water to test Free and combined chlorine. Filled water to the 25 ml mark, followed the steps and got 0.6 ppm for free chlorine and for 0.4 combined chlorine. Ph still a beautiful shade of purple meaning 8.4. CYA is 0 b/c I still see black dot. TA is reading 50 today.
 
OK. You can use 10ml to test for FC, one scoop of powder, and each drop is 0.5ppm. That's close enough for us.

Have you tried adding 10ppm of liquid chlorine yet and seeing with the FC was after 10 minutes of mixing?
 

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IceShadow said:
OK. You can use 10ml to test for FC, one scoop of powder, and each drop is 0.5ppm. That's close enough for us.

Have you tried adding 10ppm of liquid chlorine yet and seeing with the FC was after 10 minutes of mixing?
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Not yet. It seems that the rain is moving in. Hoping it passes soon. What exactly is 10ppm? I have 4 bottles of 1.34 quarts of Clorox bleach.
 
harrell_ashley said:
Not yet. It seems that the rain is moving in. Hoping it passes soon. What exactly is 10ppm? I have 4 bottles of 1.34 quarts of Clorox bleach.
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Rain won’t affect this at all. It might make you a little uncomfortable though!

You can use the Pool Math app to figure out how much to add, or the link to the old Pool Math website at the bottom of the page. It depends on your pool volume. Standard bleach is 6.25% I believe. You’ll want to be sure that that is plain bleach though. Clorox usually adds stuff to make it splash less or scented or Cloromax, which can make the pool foam and not look good. Liquid pool chlorine is best to use. They sell it at 10% or 12.5% at most hardware stores.
 
IceShadow said:
Rain won’t affect this at all. It might make you a little uncomfortable though!

You can use the Pool Math app to figure out how much to add, or the link to the old Pool Math website at the bottom of the page. It depends on your pool volume. Standard bleach is 6.25% I believe. You’ll want to be sure that that is plain bleach though. Clorox usually adds stuff to make it splash less or scented or Cloromax, which can make the pool foam and not look good. Liquid pool chlorine is best to use. They sell it at 10% or 12.5% at most hardware stores.
Click to expand...
Just ordered liquid pool chlorine from Amazon. Should be in by Friday 🤦‍♀️
Our local hardware store doesn’t have any in stock. I’ll get it faster from Amazon rather than waiting their delivery.
 

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