Cyanuric Acid 200ppm - Drain Pool?

kim stroud · Postby **kim stroud** » Fri 20 Jul, 2012 08:01

We have this same issue going on in our in ground pool after 5 evenings of pouring down rain, hail and wind that blew all the dust, debris and leaves from surrounding trees into our pool. What is the cause of this in an in-ground pool? What will be the treatment once I've drained the pool 6" below skimmer, refilled, drained again, and refilled again?

Postby **chem geek** » Fri 20 Jul, 2012 08:46

Most likely, the debris created extra chlorine demand so the chlorine level dropped and algae began to grow faster than chlorine could kill it. You need to shock the pool to kill off the algae and then after completing the shock process (it is NOT just a one-time dose of chlorinating liquid or bleach), you thereafter maintain an FC appropriate for your CYA level. Read the Pool School for more info.

Postby **czechmate** » Sat 21 Jul, 2012 16:02

It is a good practice to rectify effects of a hard rain at least as soon as the next morning.
Especially one that last longer and puts a debris in a pool.
Even rain alone with all the stuff from dirty atmosphere can upset the water balance quite easy.
Whenever you have high levels of CH or CYA you have a free water to at least bump the backwash with. The minimum amount of DE that you need to put back more then offsets the hazards presented by organic debris trapped on the surface of filter elements. Deteriorating debris is a source of phosphates that in turn consumes your free chlorine.
Just because it is out of sight and pool looks sparkling, it does not mean that there is no hidden culprit there.

Guest · Postby **Guest** » Sat 28 Jul, 2012 10:23

Pool Volume 16,000/In ground plaster/Inline Chlorinator. I used 32 oz of 6% chlorine yesterday and had Leslie's test water this morning. Of course, they said to drain pool 80% and/or replaster. We've never had these issues before and pool is 14 years old in full TX sun all day. They stated we should only use 1-2 tablets in chlorinator at a time, which may be the issue since we've always filled it and ran it at 4 for 9-10 hours a day.
FAC 0
TAC 0
CH 200
CYA 200
TA 225
pH 7.6
Copper 0
Iron 0
Is it ok to add Lye to help lower CYA. If we add overnight with pump running will it be OK to swim next day?

Postby **chem geek** » Sun 29 Jul, 2012 16:14

No, lye will not lower the CYA level. You lower CYA by a partial drain/refill since fill water has no CYA.

Your CYA got high because you are using stabilized chlorine (Trichlor tabs). There is no mystery here. The following are chemical facts independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

Read the Pool School for more info.

Postby **czechmate** » Sun 29 Jul, 2012 17:16

Pool User wrote:Is it ok to add Lye to help lower CYA. If we add overnight with pump running will it be OK to swim next day?

Daydreaming is harmless. Suggested treatment that can damage someone's investment is dangerous and irresponsible.
If there was a fraction of truth in this claim, it would be widely used all over the Globe.
Since pool industry does not benefit from the rise of CYA, but definitely from just the opposite, it is also self-explanatory that your claim or the product is a HOAX FOR THE GULLIBLE!
Chemgeek is right, as always.

CNAvSODAash · Postby **CNAvSODAash** » Sat 23 Mar, 2013 08:15

Will Soda Ash remove cyanuric acid from swimming pools?

Postby **chem geek** » Sat 23 Mar, 2013 20:47

No it won't. It is only removed by water dilution. There are some obscure ways it can go away from breakdown by bacteria if the chlorine level gets to zero and this sometimes happens over the winter, but it's not controllable and can result in a huge chlorine demand upon spring opening depending on whether the bacteria break the CYA down into carbon dioxide and nitrogen gas vs. ammonia or other chemicals.

Your suggestion of adding a base will neutralize the acid portion of CYA -- that is, it will change the pH -- but it does not break down the CYA organic ring itself and chlorine still binds to that ring so the problems of high CYA lowering the active chlorine level persist and in fact are not affected as much by changes in pH (compared to hypochlorous acid).

The following are chemical facts independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

TSH Tech · Postby **TSH Tech** » Wed 27 Mar, 2013 01:56

Whoever invents a drain-less CYN acid level reducer for swimming pools, with no adverse affects to the pool surface and pool equipment, stands to be sitting on top of a multi-billion dollar profit machine.
That individual will have more repeat business than they know what to do with.

lvrd14 · Postby **lvrd14** » Mon 06 May, 2013 18:17

Me... wrote:Shocking/chlorinating with Liquid for a bit will raise that pH also.

actually chloramines lower ph and alk

Postby **chem geek** » Wed 08 May, 2013 04:06

lvrd14 wrote:
Me... wrote:Shocking/chlorinating with Liquid for a bit will raise that pH also.

actually chloramines lower ph and alk

Huh? What are you talking about. The "liquid" is a solution of sodium hypochlorite and raises the pH upon addition but the pH drops when the chlorine is used/consumed. Chloramines are chlorine combined with ammonia and there usually isn't that much in a residential pool so chloramines won't be that high. Besides, chloramines don't lower pH and TA if you mean adding monochloramine -- what exactly are you talking about?

Gregman · Postby **Gregman** » Mon 13 May, 2013 20:39

Airate the pool. Add 1cup of baking soda per 10,000 gallons then run the pump with the Airator on full

Postby **chem geek** » Tue 14 May, 2013 01:12

Aerating the pool increases the rate of carbon dioxide outgassing and raises the pH. Then adding baking soda will raise the TA where 1 cup per 10,000 gallons raises the TA by by 4.5 ppm. Why would you do that?

Eric in San Diego · Postby **Eric in San Diego** » Mon 07 Jul, 2014 12:46

I have a similar problem in my 17K gallon in ground plaster pool with the CYN at 170. Leslies told me to drain at least half of the water. I drained more than 2/3rds. Imagine my surprise when I went back in and everything looked great EXCEPT the CYN which stayed at 170! They told me that I drained it wrong since I drianed from the bottom. They said the acid is all at the top. Is this true?

Postby **chem geek** » Mon 07 Jul, 2014 22:36

If you had circulation in the pool, then what they said was not true and it's most likely that their testing results are incorrect (and if there were no circulation then CYA might be slightly more concentrated near the bottom, not near the top). You should buy your own proper test kit, either the TFTestkits TF-100 or the Taylor K-2006.