1st test results - CYA down to ZERO?

OK, so really it is my second full test, but I thought the 51 degree H2O might have affected things. Here are my numbers:
FC 1
CC 0
TC .5
pH 7.6
Alk 110
Cal 360
Cya 0
Temp 67

30K gal., IG plaster, 2nd season. SWG.
Since I haven't been able to keep my chlorine up any higher, I'm guessing that the Cya number must be right, but it was at around 35 all last year. Could it go to zero? All the other numbers are consistent with my "real" first test this year and my numbers from last year.

Any suggestions?

Hi, Brian,

Yeah, that's a pretty easy one. My CYA has disappeared the last 2 seasons as well. Some folks dont have that problem (the "chosen ones", no doubt :D :D ) but it looks like you and I are stuck.

Solution is easy as well....add the CYA per your SWG's recommendations. It'll probably be somewhere around 60-80ppm.

Dave S.

Two other thoughts:

I don't think temp will significantly affect your tests...could be wrong..anybody have any thoughts?

Secondly, TC is the addition of FC and TC. So if FC = 1 and CC = 0, then TC is always the total of those two....1

Yeah, I know FC+CC=TC,I prolly shoulda changed it to agree but I left it the way the tests came out. The drops and the color scale aren't always easy to read - especially at that low level! CC really was 0 so that's the important thing there!

Thanks for the affirmation.

Quote:

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Originally Posted by duraleigh

I don't think temp will significantly affect your tests...could be wrong..anybody have any thoughts?

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Low temerpature can slow or inhibit the precipitation of the melamine in the CYA test. It would be best to allow the sample of water to come to normal room temperature indoors before doing it if the outside temp is cold. It would also be a good idea to let the test bottle sit for a few mintues and then shaking again before transfering to the measurment tube (with the black dot on the bottom) to insure a more accurate reading.

WARNING: This post is rated "CN", and is for Chemistry Nerds only!

Quote:

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Originally Posted by waterbear

Low temerpature can slow or inhibit the precipitation of the melamine in the CYA test. It would be best to allow the sample of water to come to normal room temperature indoors before doing it if the outside temp is cold. It would also be a good idea to let the test bottle sit for a few mintues and then shaking again before transfering to the measurment tube (with the black dot on the bottom) to insure a more accurate reading.

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Evan, while that may be true, it's very, very common for pools to be opened to ZERO CYA, even when they were closed to high levels. I'd noticed this for years, before I understood the cause, which is biodegradation of CYA. I stumbled across the cause while investigating simazine, which used to be used as an algecide. It turns out that the biodegradation of simazine involves common soil bacteria. As it happens, these bacteria usually happen to be present in pool biofilms. And, it further turned out that CYA is an intermediate of this process.

So while no one started out to study the biodegradation of CYA, it happened that they did so, along the way of numerous University and EPA funded studies of pesticide breakdown. I usually try to avoid going too far in explaining this stuff, but with your college chemistry background it should be a breeze.

Information about this is much more common now, than it was when I stumbled across it. But, it still hasn't penetrated into the pool industry.

Here are some links:

http://www.pubmedcentral.gov/article...i?artid=106326
http://en.wikipedia.org/wiki/Atrazine
http://umbbd.ahc.umn.edu/cya/cya_map.html

To quote from the last link,
"Cyanuric acid is widely used in swimming pools and is generated as a metabolic intermediate during the bacterial metabolism of s-triazine pesticides. (Karnes, 1999). It is further metabolized by bacteria and fungi via hydrolytic enzymes that ultimately release the nitrogen as ammonia. For twenty five years, it was thought that cyanuric acid metabolism proceeded through urea as an intermediate. More recent studies (Cheng et al., 2005) have shown that urea is derived from spontaneous decarboxylation of allophanate during purification of metabolites. Thus, cyanuric acid metabolism to 3 mol of ammonia is now shown to proceed exclusively via biuret and allophanate."

Please note the bit about urea and ammonia -- it's this part that's so very relevant to the spring time problem some have of adding chlorine in huge quantities, but never getting a residual: they are trying to oxidize all that ammonia!

As a concomitant, they will often note that all the algae is dead, and the pool is very clear. This happens if the pool pH happens to remain at a high (7.8+) pH level. In that case, much of the ammonia is oxidized to monochloramine, which is more effective against many forms of algae and especially, biofilms, than free chlorine. (The whole Yellow OUT process is based on monochloramine creation.)

On the other hand, if their pH is low (7.2 or less) they'll tend to form dichloramine and nitrogen trichloride, neither of which are good for much anything, but are both very 'stinky' with what most people think of as a chlorine odor.

You can investigate this further by using the following term groups:

"cyanuric acid atrazine pathway" or
"cyanuric acid atrazine biodegradation"

Ben

Ben,
I remember you stating before the board crashed that CYA CAN biodegrade! After reading through the links I wonder if it might be a good idea to test for ammonia and/or nitrogen compounds in a newly opened pool with no CYA to see if this can predict the possible high chorine demand? (realize this is just something off the top of my head There are a few easy tests for ammonia but there are some interactions that can give inaccurate results. Not sure if testing for nitrite and nitrate would be useful but if there are any areas in the pool where denitrifing bacteria might live in a closed pool with no sanitizer it is possible that it might give us an indicator.) Might be an interesting bit of research that could possibly provide us with another testing weapon to determine just what is going on in the water.

I want to STRESS that this is just conjecture on my part (and I am no expert--just a guy with enough knowlege to be dangerous:eek::rolleyes: so I am not suggesting that anyone try this!) but I would love to hear your thoughts on this.
I am going to google the search terms you suggested this weekend when I can devote some time to it and see what I can learn. Thanks!

You *could* test for ammonia and/or nitrate . . . but I don't see the point.

The solution is the same, regardless: if you add chlorine in the late PM, and it's gone by the early AM, then you need to add a lot more chlorine that same PM, regardless of whether the 'goo' as CYA leftovers, PHMB leftovers, or algae.

In other words, since the test isn't going to change* what you do, why bother?

Ben

*There is a bit of an exception. If it's ammonia or urea, keeping the pH high is best. But, if it's algae or Baquacil, low is probably better. However, the 'differential diagnosis' turns on the CYA level now, vs last fall. If it dropped a bunch, you should assume that the pH needs to be at the high end.

Wasn't good at HS chem, never took it in college - my apologies in advance. Since my pool is just 1 year old, I've been told to keep my pH down.
But since my CYA was down to 0 and my pH was on the high end when I opened up the pool, my understanding is that what I should be doing at this point is to let my pH stay on the high end and keep adding bleach in the PM until I get things under control? I'm assuming I should also add CYA now as well.

Thanks for the input!

Don't worry about the discussion above between waterbear and Ben, they're making it sound a whole lot more complicated than it really is. Just keep it simple: Yes, you need to add some CYA, either in the skimmer or in a sock or stocking in front of your return, and remember not to retest or backwash for a week or so because it takes a long time to dissolve and show up. How much you need to add will depend on your SWG instructions. And yes, keep adding bleach until you get your chlorine under control. As far as pH goes, if you're between 7.0 and 8.0, you're basically okay--the general consensus is that the lower you are on that end of the scale, the more effective your chlorine will be.......but then again, my pool "likes" a high pH so I don't try to fight it.

Hope this helps!

Janet

Question about CYA: Where does one get it and what are some product names? While waiting for a better test kit to arrive, my test strips indicate my cya is zero. Thks.

You may be able to find CYA at Walmart, Lowe's or Home Depot. If not, you'll have to get it from a pool store. Sometimes it is called stabilizer or conditioner. If the ingredient label says cyanuric acid or isocyanuric acid, it is the right thing.

First, where to find CYA: I got it at Lowes in MD, the Home Despots in the area didn't have much in the way of chemicals in stock yet. (I'll have to talk to my HD manager friend about that) approx. $10/3 lb.

Second: Tested tonight CYA up to 23. should I add some more to get in the 30-50 range? Other numbers FC/TC 2, CC 0, pH 7.8, Alk 150, Cal 350, Temp 81

Have a SWG 26,000 USG pool here in Katy (West Houston) Texas.

Just went to local Pool Warehouse on Mason and got water tested again an CYA is still low at 30 ppm and that's after adding 2 4.5 lb jugs !

So bought another jug for USD16.99+tax and will re-test after 2 weeks. You can also buy via web companies. I've looked and never seen in WalMart or Home Depot.

Walmart sells it as HTH Conditioner (almost drove my wife crazy trying to find it). Home Depot and Lowes both sell it around here. Williams Lumber sells it and has the cheapest price by far.

Does CYA degrade? Seems like a good "end of summer sale" purchase at the hardware store if it will store through the winter.

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Originally Posted by tphaggerty

Does CYA degrade? Seems like a good "end of summer sale" purchase at the hardware store if it will store through the winter.

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Not in the jar but it CAN be degraded in a closed pool under the right conditions by anerobic bacteria. (The phenomenom of closing a pool with a decent CYA level and opening it to find that there is little or none left)

Anybody have any new words of wisdom on this subject?

I closed last October with water in perfect balance, and opened the pool last weekend with green water, zero Cl, and zero CYA. The ice had only melted a few days ago.

I'm running the clorinator wide open with triclor pucks to add Cl and CYA, and kept the safety cover on to keep the sun load down. I'm thinking I'll keep up that strategy until I get the CYA up to 30 or so, then switch to bleach.

Any thoughts?

Sounds like a good plan. If you are impatient and want to get your CYA level up faster you can:

1) Put CYA into panty hose and have it hang over the side of your pool over a return. That's PatL's idea and people swear by it. Dissolves in about 24 hours.

2) Buy Instant Pool Water Conditioner by Natural Chemistry which is a slurry of the monosodium salt of CYA. It dissolves quickly in water (unlike regular CYA which takes a long time to dissolve).

3) Add Dichlor to your pool. For every 1 ppm FC you add, you will also add 0.9 ppm CYA. Dichlor quickly disolves in water.

However, your current plan should be fine as even a small amount of CYA protects chlorine from breakdown from sunlight.

As for the CYA going to zero, that is explained earlier in this thread by waterbear where there are anearobic bacteria that consume CYA. This explanation makes sense when the FC level gets to zero. What I have yet to understand is how this happens when the FC does not go too low -- I would hope that this bacteria could not survive in the presence of FC.

Richard

I wondered the same thing about how this bacteria gets into the pool and survives when there's FC.

At one point, someone said that this is a soilborne bacteria. I do have a mesh safety cover, think the bacteria could get into the pool after closing before the ice comes, when the Cl level has drifted down?

I also would have thought that the winter temperatures here in Michigan would kill this bacteria.

I hoped to be ahead of this for this year, the ice had only melted less than a week before I checked the water, and already zero CYA, zero Cl.

Winter temps don't kill all bacteria. Many just slow down their metabolism. It's only if the water in their cells freezes over that there would be a problem so bacteria living under the ice could survive. There are even some bacteria that survive in sea ice by secreting their own "anti-freeze" (essentially any high concentration of ions that can fully saturate the water in their cells will do).

It's not the temps that are the mystery so much as the survival with chlorine. The breakdown of cyanuric acid is shown in this link where you have to click on some links to see that the end product is not only carbon dioxide, but ammonia. waterbear mentioned this in another post somewhere. Anyway, so far in my own pool I haven't found any decline in CYA over the winter and I kept the FC level up the whole time. So, at best, we have inconsistent results.

The chlorine level still declines in cold water; it's just slow. In my pool with water temps around 50F and with a pool cover, the chlorine drops barely 1 ppm FC in 2 weeks at a level of around 4 ppm FC. In the summer at water temps of 88F I lose about 1 ppm FC every 2-3 days and that's with an opaque pool cover. If you never added chlorine after your winter closing, I can certainly imagine the level dropping to very low values after several months, especially if there was still some sunlight on the pool.

Richard