CYA over 100 despite using liquid chlorine

[hhoran]

Switched to liquid chlorine for all the reasons documented on this site. I had to empty and refill pool every 18 months because of excessive CYA, and here in Phoenix that water is very expensive.
But as temperatures reached triple digits this year, discovered CYA was back over 100 despite regular use of liquid chlorine. Only 24 months since last empty/refill.
Any ideas as to why the CYA got so high and how to avoid in the future?
There are maybe three 10 day periods a year when I'm out of town and use 3" tabs--otherwise all liquid chlorine

 

[PoolStored]

CYA is not naturally occurring.
So, either you added it, or your reagents are bad, you are not testing correctly, or you are using pool store testing.
How are you testing CYA?

 

[proavia]

How old are your reagents?
How do you store them?

On a side note - what is your present CH result.
Ch will climb to an unmanageable level in 2-3 years with our hard water. Many of us have plumbed our water softener to our autofill lines to mitigate this.

I can drain/refill my 12k pool in Chandler for less than $50 increase in water bill? Are you in PHX proper or one of the 'burbs?

What is the pH, TA and CH of your fill water?

 

[Donldson]

Just to confirm as there's sometimes confusion: you are saying you filled the CYA test tube with just a small amount of liquid before the dot was completely obscured?

 

[hhoran]

Yes just a small amount of water in the CYA test tube completely obscured the dot. CYA reagent is roughly a year old, Taylor R-0013 purchased from TFtestkits.
Not adding any chemical to pool other than chlorine.
I am in the city of Phoenix. At current (shoulder season rates) refilling my 16K pool would cost $98 before tax

 

[JamesW]

Only 24 months since last empty/refill.

How much CYA was added after the refill?

Any ideas as to why the CYA got so high and how to avoid in the future?

Do you ever use dichlor?

 

[JamesW]

When was the last CYA test and what was the level?

 

[TinFoilHat]

We don't have CYA in the fill water so it's being added from somewhere or your testing is bad.

 

[PoolStored]

Explain exactly your procedure and the number on the bottle of the reagent you are using.

 

[hhoran]

As explained in previous posts reagent is Taylor R-0013, purchased a year ago March. Per instructions 7ml mixed with 7ml pool water, then added to test tube until black dot at bottom could no longer be seen. Last tested late last year CYA was <40. Tested this week CYA >100.
No retail stores in Phoenix carry R-0013. Is it really possible that a bottle of R-0013 could go completely bad between November and May? There is no retail store in Phoenix that sells R-0013, so would have to do an online order to get a "fresh" bottle to test whether the problem was that my reagent went completely bad. If it is not spoiled reagent then question of how CYA could shoot from 40 to over 100 given regular use of liquid chorine.

 

[TinFoilHat]

The water levels for the test are 7.5 ml and 7.5 ml but that wouldn't cause such a large swing. Have you tried any of the local pool stores that aren't Leslies? If you do reorder the reagent from TFT then also buy the 50 ppm CYA test sample to verify your testing. Yes, they make a test sample for purchase and I should have added it to my last order just for comparison to my own tests. This is such a subjective test that the sample might help you understand the test better.

 

[magiteck]

If it is not spoiled reagent then question of how CYA could shoot from 40 to over 100 given regular use of liquid chorine.

The short answer is that it can't by that alone. The possibilities are:

• The original test result of 40 was wrong. (Either read wrong or bad reagents)
• The new test result of 100 is wrong. (Either read wrong or bad reagents)
• Something other than liquid chlorine was added to the water (Dichlor, Trichlor, CYA/Stabilizer Granules)
• A combination of the above (Maybe 40 was really 50, 100 is really 90, and something else was added ... etc.)

You mentioned some occasional tab usage during vacations - it would take > 200oz of trichlor to raise CYA from 40 to 100, or about 25 tabs. Would your occasional use have possibly added up to that?

 

[PoolStored]

Last tested late last year CYA was <40. Tested this week CYA >100.

Print these out, and START at #8.

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

www.troublefreepool.com

 

[JamesW]

question of how CYA could shoot from 40 to over 100 given regular use of liquid chorine.

It can't.

Test error or CYA is being added.

 

[Donldson]

Hey OP. I just want to give a little encouragement.

I know a lot of things are being thrown at you and can seem obvious questions are being asked or the same questions being asked more than once. It's because there is an answer to this problem and we know it can be figured out. Don't discount anything as irrelevant, it's amazing what small detail can possibly light up the bulb above someone's head. Some of the smartest people on this board are working with you on this, don't get discouraged if it seems like the impossible is happening. It's not and you're in the best place to figure out what possible thing is happening.

 

[JamesW]

Last tested late last year CYA was <40.

I recommend testing at least once a month to avoid these types of issues.

Is it really possible that a bottle of R-0013 could go completely bad between November and May?

Unless the bottle froze or got really hot, probably not.

Get some new reagent and see what it shows.

 

[Newdude]

Can we get a full set of test results, including the diluted CYA test linked above ?