How Do I Chlorinate Without Raising The Cyanuric Acid (CYA)

by Pool Water Solutions right HERE
(Virginia)


I have a 18 X 36 28,000 inground pool with a sand filter. The first test this season with the pool store gave us a reading of 90ppm in cyanuric acid. The pH was low and chlorine was low.


After balancing the pH, and shocked with liquid chlorine, the pool was still green. Pool store checked again now the cyanuric acid level is 160ppm.

Said drain 24 inches and refill. We did that.
My home test is showing about 100 on stabilizer, but I am afraid to shock or add chlorine.

We have granular and slow release tabs, both dissolve into CYA, right? How do I chlorinate without raising the CYA?

Thank you




Thanks for the question

Some granular chlorine and most chlorine tabs do have CYA and will raise the level.

The most potent form of stabilized chlorine is Dichlor. For every 10ppm of chlorine using Dichlor, your CYA will increase by 9ppm.

For every 10ppm chlorine using Trichlor tabs your CYA will increase by 6ppm.

Your Chlorine should be at least 7.5% of your CYA level and the normal CYA range is 30 - 50ppm. As the CYA increases through using Trichlor tabs the chlorine needs to increase as well.

If you allow the CYA to get to 100ppm, you need to run the chlorine at 7 - 8ppm for the chlorine to be effective. When the CYA gets this high the only way to reduce it is a partial drain and refill. There's no chemical to reduce the CYA. If your CYA is at 100ppm, and the range is 30 - 50ppm, then by draining 1/2 of the water and refilling it you'll drop the CYA to 50ppm.

The first thing to do is remove any chlorine tabs. You don't want more CYA in your pool.

Normal liquid chlorine and much of the granular chlorine is unstabilized, so it won't raise the CYA. You can use those to chlorinate your pool.

If you have hard fill water, use liquid chlorine because you don't want to add more hardness to your pool water.

Hard fill water is anything over 100ppm.

Unfortunately there's no chemical to lower the CYA. The only way to reduce it is to drain 1/3 - 1/2 of the water, refill, and balance the chemicals out.

Hope this helps and have a fun and safe swimming season.

Robert

Comments for How Do I Chlorinate Without Raising The Cyanuric Acid (CYA)

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Aug 20, 2016
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Stabilization Alternatives
by: Anonymous

So, once CYA is in the proper range it really doesn't go away? Ever? Or what causes it to have to be replenished?

Once the pool was full with fresh clean water the service man added a container (about 1 quart of powder) of what he said was stabilizer, and then a gallon of liquid chlorine.

What should the label information say about the liquid's composition? Is it possible to unintentionally get hold of a liquid that contains CYA or are all liquids unstabilized?




You only need stabilized dichlor or trichlor chlorine when the CYA get too low. It can decrease through dilution such as rain, partial drain and refill, splash out and topping off, etc... Liquid chlorine and bleach is sodium hypochlorite. Check to be sure you have that ingredient.

I've written eBooks and have devoted several pages specifically about stabilized and unstabilized chlorine. They go into much greater detail.

Clear Blue Pool eBook
How To Clear Up A Green Pool eBook
Resources

Robert

Aug 17, 2016
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High CYA
by: Anonymous

Thank you so much for all this information. My question is, is it safe to change back and forth between trichlor and liquid chlorine. Some sources advise against mixing.




Once you get your chemicals in the right range there's no reason to use trichlor granular chlorine. Liquid chlorine will take care of 99% of your needs.

Aug 16, 2016
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Stabilization Alternatives
by: Bruce Frank

I recently had to drain our pool completely because the CYA was almost 300. My pool is in full sun for about 7 hours a day in the Summer. Is there a way to stabilize the chlorine WITHOUT CYA?

Do the phosphate killer chemicals help or are they creating a buildup of any kind?




Hi Bruce. There's no effective way that I'm aware of that can stabilize chlorine without using CYA. We need to understand what CYA's role is. It's to lengthen the life of your chlorine because it's unstabilized.

First, you should only use liquid chlorine, rarely use any kind of granular chlorine, and never be totally dependent upon tabs for weekly chlorine levels.

Once you get your CYA to 30ppm only use liquid chlorine or unscented bleach. That will take care of 99% of your chlorine needs. Maintain a CYA level of 30 - 50ppm.

Robert

May 01, 2016
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Stablizer Problems Too!
by: Anonymous

WE have had an above ground 24' X 4' pool for 24 years. Last year was the first year we ran into the problem of CYA over the limit!

We had to drain our pool 3/4 down. We have been using 3" tabs in a auto clorinator all this time.

This year, same problem! Now we were told to drain our pool down 2/3 and we did. Still had the problem. Now we were told to drain the pool by 43%. This is getting rather costly!

What can we use to clorinate our pool so we don't continue to have this problem?

Steve




Hi Steve. It depends on the number of tabs your using in relation to your size pool. If you're only using tabs to chlorinate your pool the CYA will rapidly increase. If you're using 8 tabs per week in a 10k gallon pool that's lightly used, the CYA will increase.

Also, you should only be using liquid chlorine. I would suspect you might be using stabilized granular chlorine for weekly chlorination and shocking. Get the CYA to 30ppm then only use liquid chlorine for weekly chlorination. The CYA level is 30 - 50ppm. Be sure to sweep very well after adding liquid chlorine or bleach. It's heavier than water and will sink.

Remember I have eBooks available to help all of your pool water related issues.

Clear Blue Pool eBook

Resources

Robert

Sep 29, 2015
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CYA Troubles
by: Stefan from Houston

Now I don't claim to be some pool guru. Here in Texas our cya levels should be around 60-90ppm.I have found that it's very difficult to add chlorine tablets and not eventually run into stabilizer issues. Such as " chlorine lock". When this eventuality happens I normal shut the pool off "service" mode until
The water becomes still. I have found that cynaric acid does NOT mix evenly with water and will rise to the top of the water. Then I put panty hoes over the tip of the water hose and over-fill the pool for an hour or two out of the overflow drain. Then restart the pool" auto" mode and retest your chemicals the following day. In my experience it's a very rare occasion to ever drain a pool especially for chemical imbalance issues.

-Stefan b.

7 years of experience in the pool industry.

Jun 25, 2015
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CYA Reducer
by: Anonymous

Actually there's now a product called Bio-Active that's sold by Leslie's. It uses micro-organisms that target the nitrogen found in the CYA molecules and destroys them.

Once your CYA level reaches around 90ppm, the chlorine that is no longer bound by the high CYA will attack the micro-organisms and halt the reduction process.

Just FYI...less expensive than draining your pool...at least here in California.


Sep 01, 2014
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CYA Balance
by: Anonymous

Depends how the pool is used by swimmers and how much of nature gets into it via both them and vegetation. Depends on the pollution you are eliminating.
If it is not polluted much (unused for a couple of sunny weeks away from home or longer if winterised)a little chlorine/bleach (no triclor tab use) will keep the pool water looking OK and the sun (some rain would help) will speed the rebalancing/CYA elimination. If heading into winter (pool unused) CYA will dissipate (assuming the tabs are kept in store)long before your family jump in again.

If you have high CYA and high use together then yes best change the pool water. You could however switch to a short closure with a heavy shock application and after about a week the pool will be usable by the less fussy and another week by most everyone.

Lesson is if you must use triclor tabs use them as intended = to preserve chlorine in peak sunny times but when the sun is not burning off the chlorine, so CYA is not important in stabalising chlorine,change the treatment to less stable forms of chlorine or switch to other methods.

Jul 07, 2014
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CYA
by: Steve

I have a CYA turbidity tester and based on the amount of Diclor I have put in after 2 weeks clean water ,that works out to 10ppm of CYA like the tester reads.

Is there any point raising the CYA to 30 - 50, cos im just adding a tablespoon of diclor a day which is no hassle.Would the extra CYA save me from adding chlorine every day to every 2 days, if so there's not alot of point adding it.

Also once I get to 50ppm CYA do I start using unstablised chlorine to keep it at this level.




Thanks for the question Steve

Yes you can use Dichlor to chlorinate your pool but once the CYA gets to 30ppm you need to stop and use regular liquid chlorine. Don't shoot for 50ppm. That's the top range. You want to start low because using Trichlor tabs will slowly increase the CYA. For very 10ppm of chlorine added with Trichlor you'll raise the CYA by 6ppm. Or if you don't want to use Trichlor tabs you'll need to be more vigilant in testing and adjusting your chlorine level. Perhaps 2 - 3 times pe week and especially after a heavy rain or a large group swimming.

Using unstabilized chlorine will keep the CYA at the range because you stopped with the stabilized chlorine.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great Summer.

Robert

May 25, 2014
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Thank you
by: Anonymous

Thank you so much guys! I appreciate your feedback! Have a great day!

May 25, 2014
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Cya Is High
by: Anonymous

I am having the same problems. Can I use Clorox bleach because I can't find the liquid chlorine anywhere and need it right away. Also I have been afraid to partially drain the pool because of pressure. Therefore I have been letting it over flow instead, in hope that it would rid of the old water. Do you think this will help. Thanks... :)




You can use regular unscented bleach, just double the amount because it's half strength of pool chlorine.

You can fill from one end and drain from the other but doing it this way it's difficult to say how much has been drained. It's effective but you may end up wasting more water this way. You can use the multi-port valve or regular submersible pump to drain and use a couple of garden hoses to fill. Be sure to close the skimmer valves so the system is not pulling air through the system.

Aug 04, 2013
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CYANURIC ACID
by: TILDEN FROM ARKANSAS

I HAVE AN ABOVE GROUND POOL (16X48). MY TA AND PH WAS AT THE UPPER END OF THE CHART. I CHECKED WITH A LOCAL POOL CHEMICAL SUPPLIER ABOUT SOME HELP ON GETTING MY POOL CHEMISTRY BACK IN LINE. I WAS TOLD TO USE MURIATIC ACID TO LOWER THE TA AND PH.

I USED 1 GAL THE FIRST DAY AND A SECOND GAL. THE FOLLOWING DAY.THE NEXT DAY WHEN I TESTED THE WATER MY CYANURIC ACID DROPPED FROM 150/300 PPM TO 30/50 PPM. I DO NOT KNOW IF IT WAS FROM USING THE MURIATIC ACID OR IF IT WAS BECAUSE OF THE OTHER CHEMICALS GETTING INTO THEIR PROPER LEVELS. I KNOW THAT IT IS SAID THAT THERE IS NO KNOWN CHEMICAL TO LOWER THE CYA BUT THIS HELPED ME.

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