SLAM if CYA is zero?

cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#1
For past few years, every time I let my water go green over winter, all I really need to do is SLAM, and alll other numbers remain in good range. This year, I started the SLAM, and went to test my water, and found my CYA is zero. I assume it to be zero because the test is as though I am just putting water in the tube, it never gets cloudy at all, and I fill it to the top. SO my question is, do I need to get the CYA up before I start the SLAM? If you say no, and go with SLAM, then how do I calculate the target FC shock rate? DO I just go with the chart at CYA 20, or what? Here are my other numbers:

pH - 8.0 (1st time in years it has been above 7.4 - 7.6)
TA - 50
FC - 5 (was about to add more)
CYA - 0
 
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cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#3
Ok, so based on the article, I should lower pH and raise CYA first, then start the SLAM. Is there any order to the pH and CYA adjustments? Like do I add the muraic acid first, then wait 24 hours and add the stabilizer? or can I add at once, or?

Also, is the stabilizer something I can buy somewhere besides the pool store, I don't think I have ever had to buy that.
 

mknauss

Mod Squad
May 3, 2014
12,729
Laughlin, NV
#4
Put the CYA in a sock into the skimmer and add the MA. Circulate for 30 minutes and check your pH and adjust if necessary. Then add liquid chlorine and start your SLAM. The CYA in the sock will dissolve in a day or so. Assume you have 30 ppm CYA in the water for FC determination (SLAM level will be 12 ppm FC). Run your pump 24/7 during the SLAM.
 
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cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#9
Do I really have to add CYA using a sock? I have almost 7lbs to add, which is going to fill a bunch of socks. I do not have an nylons to use. The directions on the package say to slowly add to the deep end of the pool. Can I do it that way, or do I just need to use a bunch of socks?

Also, I have heard some of you say drop the sock in skimmer and other say hang it in front of jet. Are either of these methods acceptable if using the sock method?
 

mknauss

Mod Squad
May 3, 2014
12,729
Laughlin, NV
#10
Do not dump directly in the pool. It will most likely stain your liner.

You can put the socks in the skimmer (do not let them block the flow) and/or hang them in front of a return. Do not let the sock rest on the liner.
 
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cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#11
Thanks for the quick response. I just filled and packed a large tube sock, and probably only got about 1-1.5 lbs in it. At this rate, it is going to take me 5 days to get 7 lbs in, is this normal? I only have 1 skimmer. I guess I could hang 2 more socks in front of my return jets at same time? Is that OK to do?
 

borjis

LifeTime Supporter
Aug 19, 2014
2,669
Pacific NW
#14
Something very important first, before you take that cya reading correct.
What is your water temp?

If it's less than 70 degrees, you really should take a sample then bring it inside and allow it to get to room temp first.

It definitely reads differently when extremely cold.
 

ssgumby

LifeTime Supporter
Feb 17, 2012
403
Maryland
#15
Something very important first, before you take that cya reading correct.
What is your water temp?

If it's less than 70 degrees, you really should take a sample then bring it inside and allow it to get to room temp first.

It definitely reads differently when extremely cold.
Yep, totally agree with this. Mine always reads zero when I open if I dont bring it up to room temp first.
 
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cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#16
So I added my MA and CYA about 24 hours ago, and just took a reading and CYA went from zero to 50. I was shooting for 30, and added 6.75 lbs, which based on Pool Math, should have raised it to 30. Is it possible that I am testing too soon after I put it in? To go from zero to 50 would have required 11.25lbs, so the only other explanation is that my first reading was off because of the water temp being well below 70. But if that is the case, then why would I be getting a reading of 50 now?

Also, after adding the MA, the pH dropped from 8.0 to 7.0, when my target was 7.2. I added 48oz of MA, which should have dropped it from 8 to 7.2, and now it is at least down to 7, maybe a bit less. I guess I will throw 2 lbs of baking soda in now and see where that gets me.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
2,578
Damascus, MD
#17
CYA can take 2-3 days to totally dissolve. It's also possible your pool is smaller then you thought. Especially if you are going by what the builder told you. ;)

Also I want to add that reading the CYA test tube is as much an art as it is a science. You will get a lot of arguments on both sides of the coin. For me, I bought the 50 ppm reference CYA fluid and tested it. To get to 50, I can still see the dot. So when I test my water, I replicate what I saw in the test which is seeing the dot. Meaning my CYA tests a good 10-20 ppm lower than what it would test if the dot disappeared. Much like what you tested.

This is what I see in my test, testing a standard solution of 50 parts CYA. I did this test multiple times both indoors and outdoors and this is exactly what I saw, every time.

cya.jpg
 
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borjis

LifeTime Supporter
Aug 19, 2014
2,669
Pacific NW
#18
So I added my MA and CYA about 24 hours ago, and just took a reading and CYA went from zero to 50. I was shooting for 30, and added 6.75 lbs, which based on Pool Math, should have raised it to 30. Is it possible that I am testing too soon after I put it in? To go from zero to 50 would have required 11.25lbs, so the only other explanation is that my first reading was off because of the water temp being well below 70. But if that is the case, then why would I be getting a reading of 50 now?

Also, after adding the MA, the pH dropped from 8.0 to 7.0, when my target was 7.2. I added 48oz of MA, which should have dropped it from 8 to 7.2, and now it is at least down to 7, maybe a bit less. I guess I will throw 2 lbs of baking soda in now and see where that gets me.

Did you use the sock method to dissolve the cya completely, in front of a return jet or did you place it in the skimmer?

If it was sock in front of jet, you can test within about 2 hours while the pump is running the entire time (after it is all gone from the sock).

I have found that pool gallon capacity seldom matches the paperwork. My 23,000 gallon pool at my first home was actually 19,000
My current pool was 15,000 but in actuality 13,000. I believe that is why your cya is now 50, which is really not a big deal.
I run mine at 50 after initially trying it at 30 for a short time....in my case the 50 does help the chlorine last longer. So that's what I roll with now.

The ph went down a bit because you added CYA which will slightly lower ph. And I think you meant Washing Soda or Borax and not Baking Soda.
Baking soda will raise your T/A, not the ph.
 
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cholmes28

Well-known member
Jun 9, 2014
120
Marietta, GA
#19
So if it takes 2-3 days and it is not totally disolved, will that mean my test results would go up or down after fully disolved? Re size of pool, I have been using Pool Math since 2014 based on 27k gallons, and up to this point, it has been spot on, so not likely I am off on size.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
2,578
Damascus, MD
#20
So if it takes 2-3 days and it is not totally disolved, will that mean my test results would go up or down after fully disolved? Re size of pool, I have been using Pool Math since 2014 based on 27k gallons, and up to this point, it has been spot on, so not likely I am off on size.
Realistically, it would show a lower amount not being fully dissolved. Read my comment above I added some after you replied. I would be interested to know what your test shows if you make your CYA look exactly like my picture.