CYA Degradation - Happen Once - Will it Happen Again?

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happyheathen

happyheathen

0
Aug 18, 2012
224
Sacramento CA
As mentioned months ago, I OD'd the pool with CYA - it tests out at 100 ppm.

Last year it started the winter at 50 and came out 0 - ammonia formation or some such reaction was the diagnoses here.
We have a very serious drought out here, so draining 7000 gallons is not going to happen.
One change: it now has a blue "solar" cover on it (hides all the algae growing).
Aside from dumping a bit of bleach whenever I see mosquito larvae, it has no FC.

What are the odds that the CYA will dissipate?

Thanks Again!
 
Since it's happened before, it's likely to happen again if you effectively have no FC. CYA is "known" to be converted to ammonia by some soil bacteria. With no FC, you let the bacteria live in the pool. Since it's happened before, you have the right conditions and biota for it to happen again. I'd say the odds are high.
 
If it does happen again, please collect a water sample in a water-tight jar with no headspace (i.e. water filled to top) and I'll pay to have it analyzed. I've had conversations with the CEO and inventor/scientist at CuLator who doesn't believe the bacterial conversion theory because he doesn't think the conditions in pool water are anaerobic enough. The only way to be definitive about this is to analyze the water contents after such conversion to see what chemicals there are and, if still present, what bacteria or other biological microorganisms there are (some fungus is also known to do such conversion, but in soil and not reported in water).
 
I'm doing the closing on my pool this year so I likely won't have a conversion on my hands again, but if it happens, I'll let you know.

From this spring:
20140428_123454_zpslbmoatyc.jpg
 
Will collect.
Always thought there should be a thriving market for the right bug - draining is a much bigger effort than letting the pool go for a couple of months.

- - - Updated - - -

Just thought: Should I remove the cover?
Last time it was completely exposed to air and sunlight - I can see a bug not being wild about sunshine, but the oxygen was much more accessible.
 
Joel, did you measure that ammonia before you added any chlorine or was that after adding chlorine and you noticed a huge chlorine demand? Do you recall how much CYA was lost and how much FC needed to be added before an FC registered and held at least somewhat?

Dave, the scientific literature says that anaerobic conditions are needed or at least low oxygen conditions as found in aerate activated sludge systems (< 4 mg/L; pools in equilibrium with oxygen in air would have 7+ mg/L) and that it's difficult to degrade CYA in aerobic conditions, but since we see something happening in quite a few pools and they don't all seem to be anaerobic (as far as we know) it's more important that this be reproduced, however that may occur.
 
chem geek said:
Joel, did you measure that ammonia before you added any chlorine or was that after adding chlorine and you noticed a huge chlorine demand? Do you recall how much CYA was lost and how much FC needed to be added before an FC registered and held at least somewhat?
Click to expand...

I had a thread for my SLAM this spring. The ammonia issue, testing and bleach usage is fairly well documented. http://www.troublefreepool.com/threads/70486-New-Member-from-MN?p=627867&viewfull=1#post627867

I performed the chlorine demand bucket test as part of the process. http://www.troublefreepool.com/threads/6749-Bucket-test?p=54963&viewfull=1#post54963

EDIT - I don't know what the CYA was at before pool was closed as I took ownership in November of last year and did not test pool until spring thaw. It was a very cold winter, with thick ice over the entire pool. A good amount of snow melt also entered the pool.
 
Thanks. 136 ppm FC was a large demand from the bucket test, but the ammonia between 4 and 8 alone would require roughly 40-80 ppm and there may have been partially degraded CYA as well as some algae. 136 ppm FC would correspond to around 45 ppm CYA that could have been degraded.
 
chem geek said:
Thanks. 136 ppm FC was a large demand from the bucket test, but the ammonia between 4 and 8 alone would require roughly 40-80 ppm and there may have been partially degraded CYA as well as some algae. 136 ppm FC would correspond to around 45 ppm CYA that could have been degraded.
Click to expand...

This is true assuming none of the ammonia degraded to other nitrogen species and/or gassed out as nitrogen so CYA could have been higher than that, if I remember the potential mechanism suggested.
 

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Just to add an example, every winter/spring I experience about a 50% drop in CYA levels. During the winter, the water temp regularly gets below 50 F and the SWG shuts down so during this period, I just shut down the pump for a few weeks until the water gets above 50. But the downside of doing this seems to be a loss in CYA and large FC demand coming out of the low temps. But it is more than made up for by 0 run time and 0 energy cost for a few weeks.
:party:
 
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