Where did my CYA go?

[czipper]

The end of the season, I did an ascorbic acid treatment. I had a CYA of about 60 mid-season, I stopped measuring CYA because I stopped adding tricolor pucks and my understanding was that the CYA should remain steady. To do the ascorbic acid treatment, I dropped FC to zero, I added polyquat60 at the manufacturers recommended amount. When I added the AA it worked like magic and the pH dropped to pH 7.0. I added Metal Magic and I slowly brought up the FC (1 gallon of 12% bleach daily) until FC went up to 6 (6 because I was expecting a CYA of about 50-60). The staining returned, and I was disappointed, but knew that could happen that based on everything I've read. But then I took a battery of readings after everything settled down and my CYA went well under 30! Some cloudiness was evident in the CYA test, so there was still some CYA left but way less than 30. My alkalinity dropped to about 30 as well.

I replaced less than 10% of the water all season, so dilution doesn't explain my drop. Does anyone know whether the polyquat/ascorbic acid/Metal Magic treatment depletes CYA as well? Alternatively could the presence of these interfere with the CYA assay?

I'm glad to have my CYA back down so that I don't need to keep the chlorine as high, but I want to know if there is something else going on.

 

[chem geek]

CYA does slowly break down from chlorine, but that's normally around 2-3 ppm per month in pools (it's around 5 ppm in hotter spas). The larger drop might have been from bacterial degradation of CYA. Did you notice a very high chlorine demand after the AA treatment where chlorine would be consumed almost immediately?

 

[czipper]

CYA does slowly break down from chlorine, but that's normally around 2-3 ppm per month in pools (it's around 5 ppm in hotter spas). The larger drop might have been from bacterial degradation of CYA. Did you notice a very high chlorine demand after the AA treatment where chlorine would be consumed almost immediately?

2-3 ppm accounts for maybe 10 ppm of CYA. I think there was 2 bottles of bleach to get FC back on the chart, not sure whether that counts as high demand. I suppose some bacteria could have been there with the low chlorine and polyquat, as long as the AA treatment and polyquat don't impact CYA then I suppose that bacteria must be the explanation.

 

[Catanzaro]

CYA does slowly break down from chlorine, but that's normally around 2-3 ppm per month in pools (it's around 5 ppm in hotter spas).

Is that 2-3 ppm per month in pools only during certain times of the month. My pool was closed today. will I be loosing CYA in October-May of next year? Just curious? It was also my understanding that CYA does not disappear? Thank you.

 

[pragmatic]

CYA does slowly break down from chlorine, but that's normally around 2-3 ppm per month in pools (it's around 5 ppm in hotter spas). The larger drop might have been from bacterial degradation of CYA.

Thank you Chem Geek-this explains a lot! Most of the posters here don't realize CYA does in fact break-down over time / higher water temps!

 

[chem geek]

The chlorine oxidation of CYA is temperature dependent so should be negligible over the winter when the pool water temp drops. Of course, we have other ways for CYA to drop over the winter including partial drain/refill for people who close their pools and winter rain overflow for those who don't. And then there's the bacterial conversion of CYA into ammonia with huge chlorine demand upon opening or to nitrogen gas (or nitrate) which doesn't have the chlorine demand upon opening.

 

[Catanzaro]

Based on the bacterial conversion of CYA into ammonia and the chlorine demand, it seems like upon opening a pool the CYA will have a tendency to drop. So should the CYA be tested immediately upon opening a pool or about one week later?

 

[duraleigh]

Test the CYA when you open the pool and do all your testing. Once the pool water has been thoroughly circulated (maybe an hour), all your tests should be dependable and accurate.

Collectively, I think the forum worries a bit too much about disappearing CYA. We like to think of it as a stable parameter much like CH and it just isn't quite as much.

As chem geek explains there are several reason why CYA can drop in your pool (it won't go up).....some of those reasons we can't predict or fully understand but they happen nevertheless.

The takeaway is to remember to check your CYA at opening and adjust. I would also check it at least monthly during swim season and then once more when the pool is closed or stops being used for the cool season. This will be enough to insure you will have adequate CYA to manage your pool properly at all times.

 

[Catanzaro]

I would like to be prepared and purchase the CYA before hand. No one carries it around here in NJ & the Liquid Form is just too expensive. Everything else I have. I am even trying to order enough liquid chlorine 12.5% delivered so it can be split up between 4 homeowners. It just seems like the bleach at some of the stores are older then 6 months, etc.

 

[pragmatic]

I would like to be prepared and purchase the CYA before hand. No one carries it around here in NJ & the Liquid Form is just too expensive. Everything else I have. I am even trying to order enough liquid chlorine 12.5% delivered so it can be split up between 4 homeowners. It just seems like the bleach at some of the stores are older then 6 months, etc.

Use the trichlor pucks-they are CYA+Cl. A perfect way to deliver and cheap.

 

[JVTrain]

Use the trichlor pucks-they are CYA+Cl. A perfect way to deliver and cheap.

This can be a good short term, slow delivery method to raise CYA while maintaining free chlorine levels. If you need to raise quickly, granular CYA in a sock is best. Long term use of Trichlor pucks can of course cause problems.

 

[Catanzaro]

I removed my FROG System for this reason. No minerals and No bac pac (stabilized chlorine granules), just like pucks for this reason. Hard to control the amount of CYA in the pool. Liquid chlorine is instant.

I like the liquid chlorine method. It may just be worth the extra $10 for the liquid CYA next year in the event I need to raise it. I am between 40-50 (No more then 50) and this is where I should be. Unless I drop to 30, then I will need some.

 

[timerguy]

Found some at the Kmart in brick, nj http://www.kmart.com/aqua-chem-my-salt-pool-6.5-lb-saltwater/p-004W006376877001P

 

[Catanzaro]

I believe I need this as I have a Sand Filter. This is only available on line.



http://www.kmart.com/aqua-chem-stabilizer/p-004W545180110001P?prdNo=9&blockNo=9&blockType=G9

 

[timerguy]

The filter is irrelevent. But that will work too. The one I recommend yesterday was in stock at the Brick store. But the price is right for your linked bottle. 3 lb for $5 is a great price! To bad it isn't available for instore pickup. How much will it cost to ship it? Oh! And though It says My Salt Pool, Stabilizer is Stabilizer and will work in any pool!

 

[Catanzaro]

Yes, you can not beat that price. Maybe I can have them deliver it to the store.

 

[timerguy]

It says not available for instore pickup. If the shipping is over $6.50, what I recommended yesterday is a better value.

 

[Catanzaro]

I will pick up the stabilizer in the store in Brick when I am down there or look for another K-Mart near me, etc. Thank you.

 

[czipper]

My goodness, so much activity on my post about CYA depletion! I have been floating pucks since discovering my CYA was low (see the posts that started the thread). My CYA is just about 30 a week later and shouldn't climb much higher before closing. I am hoping to have it around 40 ppm on closing day.

I thought about using the liquid CYA at the start of the season, but the 1 gallon bottle was only for treating 10,000 gallons (my pool is 25K) and I wanted to go from zero to about 30 or 40. This would require 10-12 bottles, and at 35 bucks a pop I would be paying 10 times more than other ways to add it, either directly or in combination with chlorine. I often pay for convenience but I felt that price was abusive.

For the record, I actually think that using the Trichlor pucks until the CYA gets to the level you are looking for is the best way to add CYA, it kills two birds with one stone while your CYA levels are low. After understanding the TFP approach, anyone will realize that you can't rely on them exclusively and you have to stop using them at some point, but everyone here is aware of the CYA problem and can easily figure out when to stop using them and convert to bleach. Starting up with them reduces you chlorine budget for the time that you are using them, who doesn't appreciate that?

To re-address my stains, I raised pH to 7.6 and added 3 bottles of ProTeam Metal magic and within an hour the rust stained steps were white again. This year I didn't take the metal staining into account at all with my pool chemistry since it was my first season with a pool. the pH was pretty steady at 7.4 for most of the season, but these conditions obvioulsy permissive for metal precipitation. I guess I'll have to play around with the chemistry to prevent metal stains next year. I am guessing keeping the pH slightly higher and keeping sequestrant in the pool will be part of my regimen next year.

 

[Catanzaro]

Where is your CYA level @ this moment? Did you use the Calculator? I started with fresh water last year and there was only 3 bottles on the instant placed in the pool. My stabilizer level has stayed @ 40 all year long and I have had no issues. Each bottle does treat 10,000 gallons but it is the calculator that will tell you what you need.

I checked the CYA on Pool Math and even if you lost all your CYA and were @ 0 and needed to go to 40, you would need 346 oz. of liquid stabilizer. Unless something funky is going on in your pool and you keep loosing CYA. But this is for the experts to respond on this one.

How did you figure out that you needed all those bottles. 3 lbs. of stabilizer or 54 ounces is $5 on the K-Mart website. You would only need about $12 worth of powdered stabilizer, which is a lot less expensive then the liquid that the pool store sells @ around $25 in NJ. So the liquid form would cost $75 vs. $20 with shipping.