Cyanuric Acid 200ppm - Drain Pool?

What is floc, clarifier, stabilizer, cyanuric acid,
algaecide, brightener, dichlor, sodium hypo,
sodium bisulfate, ....??
firehall90

Cyanuric Acid 200ppm - Drain Pool?

Postby firehall90 » Fri 09 Apr, 2010 15:52

chem geek wrote:
firehall90 wrote:The idea of draining a pool to lower cyanuric acid is a bit outdated. A 40k pool can have this level reduced by 100ppm by adding 2lbs of lye. It will in effect raise the pH, but only slightly and lye can be purchased at most home improvement stores in the plumbing department as a drain unclogger. Only pure lye should be used as any other product will contain additional metals such as alluminum. the ingredient will list 100% calcium chloride if it is ture lye. The same is used in water treatment at plants the utilize isocyanuric acid to stabilize chlorine.

What? It is true that a high pH of 9-10 AND high levels of chlorine can oxidize Cyanuric Acid and is sometimes done for water treatment, but this isn't something to be done safely in a pool. The high pH can create calcium carbonate scale and the very high chlorine levels required can oxidize and corrode what is in the pool (including metal).

Lye is just sodium hydroxide (not calcium chloride -- you are thinking of calcium hardness increaser) and raises pH. There is NOTHING special about lye. Any strong base can be used to raise the pH, even 20 Mule Team Borax (sodium tetraborate decahydrate). Adding 2 pounds of lye to a 40,000 gallon pool that has a TA level of 150 ppm with CYA of 100 ppm would raise the pH from 7.5 to 8.9. If the pool was near saturation with calcium carbonate to protect plaster surfaces, the index would get to about +1.5 which would very likely cause scaling.

Also, the CYA will not drop just from high pH alone. It requires either an enzyme-driven pathway or a lot of oxidizer in the water. This scientific paper talks about the biodegradation of CYA by bacteria and this link describes that pathway in more detail, but this isn't a very reliable way to degrade CYA in a pool and it produces a LOT of ammonia that then needs to be oxidized or otherwise removed. [&u=%2Fneurl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1tahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4,075,094.PN.&OS=PN/4,075,094&RS=PN/4,075,094]This patent[/url] describes the oxidation of CYA by chlorine at a pH of 9-10, but it takes a LOT of chlorine to do so -- needing a minimum of 2.5 times as much FC as the CYA you want to eliminate (so 250 ppm FC to get rid of 100 ppm CYA) -- clearly impractical.

Apologies for the calcium chloride, and for references I provide these:

Patent US 5,194,162 http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5,194,162.PN.&OS=PN/5,194,162&RS=PN/5,194,162
Patent US 4,389,318 http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F4389318
Patent US 5,021,186 http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F5021186

The later two referred to by the first as supporting references. The pH of 5.0 to 7.5 is markedly different than 9.0-10. The addition of sodium hypochlorite only assists in speeding the process. The idea here is simply to reduce the CYA, not increase the pH…it is simply a side effect of reducing the CYA concentration which increases the pH. Once the CYA is reduced he can adjust the pH as needed.


chem geek
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Cyanuric Acid 200ppm - Drain Pool?

Postby chem geek » Fri 09 Apr, 2010 23:13

The first (most recent) patent is the relevant one and it says to add 1/2 gallon of 5% sodium hydroxide (equivalent to about 3-1/2 ounces weight of sodium hydroxide) to 10,000 gallons. If I assume a TA of 120 ppm and a CYA of 100 ppm and a starting pH of 7.5, then the pH would rise to only 7.64.

This is absolutely ridiculous to assume that this would have any effect on the CYA level. This is a patent, not a peer-reviewed scientific paper and is essentially bunk. Patents don't have to actually make any sense -- they just have to be novel enough to get past the patent examiner. There are plenty of crazy patents on the books.

Note that in the patent you listed that in the detailed description of the invention it says, "In order to treat swimming pool water which has accumulated isocyanuric acid therein as a result of repeated use of stabilized chlorinating tablets or other isocyanurate additions, the inventor contemplates the addition of an effective amount of sodium hydroxide (NaOH) to the pool water." (bold emphasis mine). This particular inventor appears to be contemplating his navel. The patent is not assigned to any corporation and there are no experiments or specific exhibits with actual results listed.
Guest

Cyanuric Acid 200ppm - Drain Pool?

Postby Guest » Fri 09 Apr, 2010 23:41

This particular inventor appears to be contemplating his navel.
:lol:
Would be great if it worked, though.
Pool Rookie

Cyanuric Acid 200ppm - Drain Pool?

Postby Pool Rookie » Mon 11 Jun, 2012 18:19

I am in a similar situation. i had an algea issue and went through a process that Leslie Pools set me up with. It for sure got rid of the algea but now I have no registered chlorine of any kind and my Cyanuric Acid is off the chart. What to do??? I have been told that the only thing to do is drain it. I tried draining some but it got to the point where my pump began to cavitate. Can any thing else go bad? All i want to do it SWIM! Please help!
chem geek
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Cyanuric Acid 200ppm - Drain Pool?

Postby chem geek » Mon 11 Jun, 2012 23:11

Leslie's probably had you use Chlor-Brite which is Dichlor to shock the pool and that increased the CYA level a lot (if they had you use Power Powder Plus then that's Cal-Hypo and increases Calcium Hardness). You can just use chlorinating liquid or bleach and raise your FC level to around 7.5% of the CYA level to prevent algae growth and over time do partial drain/refill or continuous dilution to get the CYA lower. Or if you want to have a lower FC level and not get algae then use a supplemental algicide such as Polyquat 60 weekly.
kim stroud

Cyanuric Acid 200ppm - Drain Pool?

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?
chem geek
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Cyanuric Acid 200ppm - Drain Pool?

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.
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Cyanuric Acid 200ppm - Drain Pool?

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

Cyanuric Acid 200ppm - Drain Pool?

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?
chem geek
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Cyanuric Acid 200ppm - Drain Pool?

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.

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