CYA Removal

[JKB121]

So here's my situation.

27' round above ground, figuring roughly 18,000 gallons.

CYA has leaped to 212 this year. Feeding 1" Trichlor only and maintaining 7.0 ppm FC (give or take).

Used about 50 pounds of Trichlor in 5 1/2 months. Hard to believe there is that much CYA in a 50 pound bucket. I started new last year and only added 30 ppm of Stabilizer. At the end of that year we were at 130/140 ppm.

I'm at 212 this morning. (about 5 1/2 months open this year)

Other numbers just in case: FC 7.25; CC 7.25; ALK 125; CH 200; PH 7.4

My goal is to get down to 40 ppm, but slowly. I've read a lot of negative stories about draining an above ground pool. Using simple logic, since tap water has NO CYA, to get down to 40 ppm from 212 ppm I'd basically have to drain almost all the water.

I'm wondering if I wait until we are ready to shut down the heater for the year, and before winterizing, if I would pull about 1 foot out and replace, circulate a day, pull another foot out and replace, how many times would it take to get down to where I want to be? Anyone ever do it that way. I really don't want to take 75% of the water out at one time. The tarp method seems awkward..... uggh.

 

[JohnT]

If I was doing it, I’d wait until spring. Many people lose a significant amount of CYA over the winter without doing anything. Just stop adding anything with CYA in it.

 

[JKB121]

If I was doing it, I’d wait until spring. Many people lose a significant amount of CYA over the winter without doing anything. Just stop adding anything with CYA in it.

I was under the impression that cya was like calcium and once it was in it never came out. I'm thinking it probably wouldn't drop 120 PPM over the winter though? Waiting until spring is definitely an option. If it didn't drop drastically it still leaves the original question on slowly draining and refilling.

 

[Bperry]

ColorQ digital tester. ColorQ high limit is 125, so I mixed equal parts of pool water and tap water and used that sample to get 106. 106 X 2 = 212.

TFP generally doesn’t rely on that sort of equipment to get reliable test results. I haven’t used that one personally though the guidance around here is to get a reliable test kit and then report back with test results from that kit to get good advice. If your CYA is actually 200+, then you’d need to exchange 3/4 of the water to get back down to ~50ppm. But if the test isn’t reliable you may drain for reason or not enough.

 

[TexEdmond]

Scratch that.... tested CYA this morning.... I'm at 212. Uggh.

YOWWWZER!

I simply expected the CYA to creep up over the summer.

Looks like you got your wish... What were you using for chlorine? I see you mentioned the tabs were CYA test tabs, not trichlor.

Fix it and go liquid Chlorine!!!! The fix it part is causing me worry.

Tell us more about your worries. Is your fill water super expensive? Looks like you'll probably need at least 2 partial drain / refills if you want to go that route for the safety of your liner. Otherwise I think folks have had good luck with the tarp method for sequestering fresh water on one side of the pool while draining from the other. It's so worth it to just not have to worry about things anymore... I did mine in June with 2 partial drain / refills and even though it was a hassle at the time, I am super grateful I did it. I read the stories of people SLAMming their pools and it seems like I got the easy job in comparison.

 

[JKB121]

TFP generally doesn’t rely on that sort of equipment to get reliable test results.

I think the LaMotte ColorQ is pretty reliable. In comparison, I took a sample to the store where they have the fancy spin test.

My CYA: 212. Their CYA 203
My CH: 200. Their CH 209
My PH: 7.4. Their PH 7.3
My ALK: 120. Their ALK 90
My FC: 7.6. Their FC: 7.2
My TC: 7.6. Their TC: 7.5

Other than CL and ALK, I call them dead on.
I got the ColorQ almost 2 years ago based on comments here. I've compared numbers with the pool store about 3 times each year and found nothing alarming.

 

[JKB121]

YOWWWZER!


Looks like you got your wish... What were you using for chlorine? I see you mentioned the tabs were CYA test tabs, not trichlor.


Tell us more about your worries. Is your fill water super expensive? Looks like you'll probably need at least 2 partial drain / refills if you want to go that route for the safety of your liner. Otherwise I think folks have had good luck with the tarp method for sequestering fresh water on one side of the pool while draining from the other. It's so worth it to just not have to worry about things anymore... I did mine in June with 2 partial drain / refills and even though it was a hassle at the time, I am super grateful I did it. I read the stories of people SLAMming their pools and it seems like I got the easy job in comparison.

Water cost is not the issue. My only issue is exposing the liner and it moving or wrinkling. Other than that, I have no issues. Reading some have issues with it not going back properly. I can fill the entire pool from empty to max in 32 hours with a hose.

 

[Newdude]

I got the ColorQ almost 2 years ago based on comments here

It's generally not reccomended, although there are people that like it. Per pool school :

The LaMotte ColorQ is not recommended as your primary test kit.

The ColorQ is an "electronic eye", aka a colorimeter, and colorimetry can be very difficult to get right. If the light source ages, or the (plastic!!) lenses get a little fogged up or the cuvette is dirty, the results can be easily thrown off.

The ColorQ works fine for routine tests. The problem with any test system that uses the color of the water to determine a test number is that several things can interfere with the accuracy. For the ColorQ, the test tubes need to be newish with no scratches and the inside of the test device, which has a light and a receiver, must also be clean and not scratched.

Another problem is that the test sample is small. This means you have to be very accurate when you fill the test tube and again when you add the drops if you want the results to be the same.[1]

Also, LaMotte is using a reagent that changes hue (intensity) relative to concentration, but the chemistry of that color change is not at all linear. Color changes can be "linearized" over small changes in concentration but pool water typically spans a very large range for CH (<50ppm all the way above 1000ppm). To expect a reagent dye to have discernible color difference over such an enormous range is unrealistic. This also applies to their FC measurement because the unit is looking at differences in the shade of pink generated by the DPD indicator. That change in pink intensity is not linear at all and can be easily thrown off.[2]

This is why Taylor uses titration. While seeing the color change from red-violet to light blue for CH measurements can be difficult, the transition exists and can be easily seen under the right conditions. It's not perfect either, but titration is always going to be way more accurate than color comparison.

The TF-100/K-2006 do not rely on the actual color of the sample, but rather when the color suddenly changes from one color to another. The actual color is not all that important.[3]

You can use the ColorQ to give a feel for any changes to the balance of your pool water. As an example, if you really don't care if your FC is 7 or 8 ppm, you can see what your FC is today vs. the last time you tested. This test info lets you know if you need to increase or decrease the amount of FC in your pool. In most cases this is all the accuracy that you need. When you need to know for sure exactly what your FC is, you should use your TF-100/K-2006C FAS/DPD chlorine test.

 

[JohnT]

I was under the impression that cya was like calcium and once it was in it never came out. I'm thinking it probably wouldn't drop 120 PPM over the winter though? Waiting until spring is definitely an option. If it didn't drop drastically it still leaves the original question on slowly draining and refilling.

I've always had 0ppm in the spring, and most people in cold climates have similar results. You may be pleasantly surprised. You will certainly lose some, which will make dilution easier. Rain and snow over over the winter can also help

 

[JKB121]

I've always had 0ppm in the spring, and most people in cold climates have similar results. You may be pleasantly surprised. You will certainly lose some, which will make dilution easier. Rain and snow over over the winter can also help

Pleasantly surprised.....???? I'd be thrilled !!!!. Doesn't cost anything to wait and see. Plus, I wasn't going to do anything while the water is still warm. Thank you.

 

[Newdude]

Pleasantly surprised.....???? I'd be thrilled !!!!. Doesn't cost anything to wait and see. Plus, I wasn't going to do anything while the water is still warm. Thank you.

We get about 3 ft of precipitation each off season, which is 2/3 of an inground pool and 3/4 of an above ground pool of free water exchange And CYA breaks down 4-5 ppm a month which is hardly noticeable when the pool is open, but when you walk away for 5-6 months……. Yeah. Between the 2, it wipes most of us out. But you need either to stay open or to have a permeable cover.

 

[JKB121]

We get about 3 ft of precipitation each off season, which is 2/3 of an inground pool and 3/4 of an above ground pool of free water exchange And CYA breaks down 4-5 ppm a month which is hardly noticeable when the pool is open, but when you walk away for 5-6 months……. Yeah. Between the 2, it wipes most of us out. But you need either to stay open or to have a permeable cover.

Makes sense. My winter cover holds water tight... We pump it off.

 

[Newdude]

My winter cover holds water tight... We pump it off.

cover it until the leaves are down and then let it be open for the rest of the winter. Drain from the bottom with a submersible pump when needed.