My CYA was at 80–confirmed by 2 separate tests. My SLAM took nearly 2 weeks and a lot of bleach to sustain a shock level of 31ppm (also confirming the CYA Reading was correct). After successful SLAM and OCLT I opted to reduce my CYA to lower my target FC and spend on bleach. I drained about 8” off a 22,000 gallon pool and refilled. I figured my new CYA would be somewhere in the 50-70 range as there is no way I drained more than 3-4K gallons. CYA is barely registering 20–I can still see the dot. Reagents are fresh and using. a TF-100 kit. And I know I’m doing the test correctly. What could possible account for almost no CYA after a 10-15% water replacement on a CYA of 80. Anyone have any ideas?
CYA Frustrations
- Thread starter Poolboy6
- Start date
Mendy48
Bronze Supporter
Mmmmmm ... This is interesting... since you're certain your doing the test correctly, I'm not going to comment on it...Another things is that CYA does oxidize with strong UV impact. I'm not sure if this has something to do with it. I'll await for others to chime in here shortly.
- Jun 7, 2017
- 9,056
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
Was this the first test after the SLAM? Test again today and see if it registers the same. Do a complete set of tests to see where you stand. If all looks good and your FC is good and CYA has not budged, add more CYA.
I retested twice and even begrudgingly went to the pool store--my CYA is 10 after removing 3-4k gallons from a 22k pool, that had a CYA of 80. Pool Math said I would have had to remove and replace 65% of my water to achieve a CYA of 30--no way I replaced more than 10-15%. I just don't understand how that is even possible. Again the 80 PPM was definitely accurate based on multiple tests and a successful SLAM and OCLT (@ 31 ppm FC). Water temp was 82. It is definitely a mystery. I'd appreciate anyone's insight to how this is remotely possible.
But I've accepted the readings and now after all that I have to raise my CYA after wanting to lower it. I'll bring it to 30 but I want to try and do it with some remaining Sodium Dichloro-S-Triazinetrione Chlorbrite. Does anyone know how much CYA is in Chlorbrite and how to calculate the increase in CYA I want to achieve? I'll obviously go slow and test often. This is beyond frustrating.
Many thanks.
FC: 6
CC: 0
PH: 7.7
ALK: 120
CH: 30
CYA 10
But I've accepted the readings and now after all that I have to raise my CYA after wanting to lower it. I'll bring it to 30 but I want to try and do it with some remaining Sodium Dichloro-S-Triazinetrione Chlorbrite. Does anyone know how much CYA is in Chlorbrite and how to calculate the increase in CYA I want to achieve? I'll obviously go slow and test often. This is beyond frustrating.
Many thanks.
FC: 6
CC: 0
PH: 7.7
ALK: 120
CH: 30
CYA 10
According to PoolMath you need 3lbs 11 ounces. I would add half that amount first. Put it in a sock and drop the sock in the skimmer basket with the pump running. After it has dissolved test again.
Well, it's not possible. There is an error somewhere. You can accept and go forward or you can dig back and likely figure it out.
1. It has nothing to do with UV
2. What tests did you perform to get 80 (what type and by whom)
3. How are you now getting 10 ppm CYA? The most refined test only goes to 20.
I ran the TF-100 twice (once with an old R-0013 reagent; and again with a newly purchased bottle of R-0013) both had readings of 80; I had a third test done at the pool store confirming the 80. I feel confident about the 80 because I also SLAMMED using that figure to calculate the 31 ppm FC that ultimately lead to a successful OCLT. I redid the test twice AFTER the drain and replace of 10-15% and got reading of ~20 both times; and the pool store reading was 10 (I think it is likely closer to 15).
It's truly befuddling as I am highly confident all CYA testing is accurate and the volume of water removed cannot be more that 10-15%. 6-8 inches on a 22k pool (3.5 and 7.5 feet 18 x 36) drained for 6 hours; and refilled with a garden hose (I timed and measured the flow =10 gallons per minute =600 per hour and it ran for about 5 hours = 3,000 gallons). No way it was the 65%+ Pool Math said was needed to reduce CYA that much.
I've moved on and accepted it but please try and pick apart my math.
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thanks!! somehow I'm not seeing where in pool math it gives that specific weight on dichlor to raise CYA. as the dichlor field is for FC and the CYA field has separate values. Are you doing an independent calculation?
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thanks!! somehow I'm not seeing where in pool math it gives that specific weight on dichlor to raise CYA. as the dichlor field is for FC and the CYA field has separate values. Are you doing an independent calculation?
Your math is not the issue.
The Pool Store test is a non-starter. I don't trust it nearly as much as I trust your own testing.
Proving the 80 ppm with a successful SLAM is not relevant.......The SLAM could be equally successful with CYA of 40ppm.
So the latest Pool Store test is 10 or 15? Again, throw that out....no test goes that low.
You apparently have a valid CYA test that YOU performed and got less than 20, is that correct? Did you do the tests that yielded 80 ppm?
You have an event that simply cannot happen so something is making it APPEAR to have happened. Are the test results you post above your test or the pool stores?
The Pool Store test is a non-starter. I don't trust it nearly as much as I trust your own testing.
Proving the 80 ppm with a successful SLAM is not relevant.......The SLAM could be equally successful with CYA of 40ppm.
So the latest Pool Store test is 10 or 15? Again, throw that out....no test goes that low.
You apparently have a valid CYA test that YOU performed and got less than 20, is that correct? Did you do the tests that yielded 80 ppm?
You have an event that simply cannot happen so something is making it APPEAR to have happened. Are the test results you post above your test or the pool stores?
I was just quoting how much CYA alone you would need to raise it to 30. Down at the bottom of poolmath is a section called "effect of adding chemicals" If you plug in 16 ounces of trichlor for a 22,000 gallon pool, it will raise FC by 5ppm and CYA by 3ppm. Its ok to use when you are a little low on CYA, but since you want to raise yours by about 20ppm, it is not the most efficient way to do so, unless you want your FC to be 25ppm.
The 10 ppm CYA was the pool store. All other findings are testing I did with the TF-100. As you know the CYA test is a little subjective. At 20 on the cylinder its starts to obscure the dot but it can still be seen. I use the other data point from the store to suggest it might be 15 ppm. You're right. Something is wrong but even if did the 2 previous CYA tests wrong and was off by 50% or 40 ppm. To get a CYA of 20 after the replacement would require a 50% water replacement (10-11k gallons) and that just didn't happen. Your correct I could have been over SLAMMING but again the minimum amount of water exchange is the compelling data point I feel. Oh well. I'm moving on. Thanks.
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Thank you. I didn't know that function was there!!!
Flying Tivo
TFP Guide
- Jan 24, 2017
- 2,946
- Pool Size
- 7500
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Link below to a chemgeek post I found after I had a loss of about 20 CYA over 5 weeks earlier this summer. If I read it right (it is admittedly way over my head) he supports the idea that CYA oxidation can happen, but the amount of loss Poolboy saw sounds extreme. In my own case, I accepted oxidation as what must have happened as I was confident in my testing.
The other possibility in the chemgeek post is ammonia conversion by bacteria. Would that be noticeable just by the smell of the pool?
https://www.troublefreepool.com/threads/8498-Degradation-of-Cyanuric-Acid-(CYA)
The other possibility in the chemgeek post is ammonia conversion by bacteria. Would that be noticeable just by the smell of the pool?
https://www.troublefreepool.com/threads/8498-Degradation-of-Cyanuric-Acid-(CYA)
I syphoned off 3,000 gallons 1 time over a 6 hour period. Why does that matter?
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Interesting. I’ll read. Thanks.
Not necessarily, apparently people vary widely in their ability to smell ammonia. OSHA states an odor threshold between 5 and 50ppm. A pool is probably more like 0-10ppm. So some overlap but not always.
Hard to see the bacteria showing up mid slam.
For your 80 results, how soon after you last put in cya were those tests done? Just wondering if it was fully mixed at that point.
Flying Tivo
TFP Guide
- Jan 24, 2017
- 2,946
- Pool Size
- 7500
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Just because it's called dilution. The first siphon dropped about 17-20% of your CYA. Your next few backwashes could have dropped it even further! Just as everyone else mentioned don't obsess about it , just test and adjust accordingly!
Thanks. I’m not obsessing. Just want to find out what happened so it’s not repeated. It’s rather peculiar. Still unsure of what your suggesting by “next few backwashes”. ?
It was a singular event to siphon off 3,000 gallons, which should have been ~13% of the total volume (22k) and CYA of 80. No additional backwashes were conducted.
- Jun 7, 2017
- 9,056
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
It is possible you had a bacteria infection that was feeding off your CYA and your SLAM killed the bacteria before they could consume all of your CYA.