Where is my CYA going?

mharner6

Member
May 25, 2018
9
Manassas, VA
Hello everyone, first post here. We have had our pool for about a year now. The builder finished last May so he got everything in order and it as a fairly easy season for maintenance, just a lot of MA to keep pH down. I opened the pool two weeks ago, it was a little green but cleared up quickly and has stayed crystal clear. Here is what the water test looked like yesterday:

FC - 5.5
pH - <8 (added MA)
TA - 130 (bringing it down with MA)
CH - 210 (ordered, should be here this week)
CYA - ??? can't get a reading.

So last year the builder threw a bunch of CYA in the skimmer and I ordered the 20 lb. Puritech box from Amazon as it needed more, but I never threw it in the pool. Not having a full grasp on the maintenance, I figured everything was good as FC was holding in the 3-4 range but I may have had the SWG working a little more than necessary. This year I tested for CYA and it appears there is none, or it's very low. We had a ton of rain over the winter and I was draining through the skimmer what seemed like every two weeks, so I know I lost quite a bit, salt was low as well. To get CYA up, pool math says I need 13lbs to get to 70. Over the course of the past two weeks I have slowly been adding it, first 6 lbs, then 3, test again, 3 more lbs. The problem is, recent tests are showing nothing. I am using the sock in the skimmer method and it dissolves fairly quickly, and I keep the pump running overnight (except for once, oops!)

I have also read all the threads on proper testing techniques and watched all the videos. After the initial dose, the test showed between 30 and 40, so I thought I was getting somewhere. However, at some point in all the testing I had to order new reagent and I do not recall if that first test was with new reagent or left over from last year. All the tests since then (with new reagent that expires in 2020) show absolutely nothing, I can fill the tube completely and clearly see the dot, back to the sun, facing the sun, to the side, inside with artificial lighting, flash light shining through the tube... nothing.

I am thinking either the reagent is bad, or maybe the CYA as it sat in the garage all winter (unopened). Anything else it could possibly be? Is it possible it's stuck in the filter and needs more time? Maybe something in the water eating away at it? Ammonia (haven't tested for it)?

The last dose was on Wednesday and I am not adding anymore until I can pinpoint the issue. Plus, at this point I am sure I have added more than 13lbs and don't want to have to replace water. I plan to pick up new reagent at the store today and test with that. Thanks in advance and sorry for the long post!
 

Oly

Gold Supporter
Jun 28, 2017
957
Fresno, CA
You are wise to go slowly adding CYA to reach your target. Try letting the test water warm up to room temp before testing and be sure to mix well and for enough time. Also pour the mix back into the mix bottle, shake and retest, there is no time limit.
It's a quirky test and the CYA may take days after an application to register. Adding too much too fast is difficult to remedy.
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,560
Houston, Texas
Hi, welcome to TFP! If you are able to maintain a chlorine level then I would only suspect ammonia if you had dosed enough to reach 10ppm and within a few minutes were down to 5 ppm. Ammonia consumes chlorine very quickly so I doubt that is the issue. Do you still have the container for the CYA you have been adding? If you post a picture of it that may help us troubleshoot your problem.
 

mharner6

Member
May 25, 2018
9
Manassas, VA
Sorry, I meant to add the water temp is 81. Did a test this morning with same results, even dumped the mix back in, shook it more and tried several times more. Getting ready to head out to get more reagent, may as well take a water sample and see if the pool store detects CYA.
 

Mr Bruce

TFP Guide
Mar 24, 2014
2,336
Greenville, SC
Do you have an autofill?

You could make a very high % mixture CYA/water, like a teaspoon in a bucket and test that to see if you get anything.
 

mharner6

Member
May 25, 2018
9
Manassas, VA
No autofill, and we didn't get much rain during this process.

Good idea on the small sample, that should at least rule out a bad batch of CYA. Test results at the store showed CYA at 30, as well at phosphates at 1000. After a quick read, I am not concerned about the phosphates as FC is well maintained. FC showed 6.8 today (.2 CC) so I backed the SWG% down some.

I also picked up some new reagent and that appears to be cloudier, although I think my eyes have a permanent dot etched in them from all this testing :rolleyes:. But seriously, back to back tests did differ slightly.

I went ahead and ordered the blue devil test as well.

Thanks for all the help, this site is awesome!
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,560
Houston, Texas
Are there any dates on the suspect bottle of CYA reagent? Was it in the garage all winter too? Where did you get it from?
 

mharner6

Member
May 25, 2018
9
Manassas, VA
I purchased two new bottles this year, one from Amazon and one from the local pool store and both expire next year. I picked up some stabilizer at the store today and the consistency is very different than what I bought from Amazon. The store bought is like kitty litter, whereas the Amazon stuff is a very fine powder that dissolved from the sock very fast.

I am currently running a small scale test with the new CYA and it takes much longer to dissolve. Yesterday's small scale test with the old CYA still didn't register on the test, so at this point I can only assume that the old stuff is bad or they sent me the wrong product.
 

mharner6

Member
May 25, 2018
9
Manassas, VA
The small scale test is confirming that whatever I received from amazon is not CYA. I mixed .1 oz of the new CYA in a pitcher and it is not even close to dissolved, but the test shows well over 100.
 

mharner6

Member
May 25, 2018
9
Manassas, VA
So I believe what I received from Puritech (Amazon) was actually alkalinity increaser, which would explain why after getting the TA down to around 80 with MA when I opened the pool, it is back up to 130. It is not quite as fine as the Arm and Hammer baking soda I have, but the math works out to about a 50 ppm increase for the 15lbs I have added. I guess that also explains why I have to keep adding MA to control pH.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
20,193
Laughlin, NV
Good catch!
Mis labeling chemicals is not a good business practice. I suggest buying from a different source in the future.
 

mharner6

Member
May 25, 2018
9
Manassas, VA
Thanks! I started a claim with Amazon and will accept either a refund or replacement as I will still need more in the future. If they decide to replace it, I at least know what to look for and will do another small scale test before adding it to the pool.

For fun, I tested the water sample from yesterday's small scale test with the Amazon product and the TA was through the roof. After 100 drops and not seeing a hint of red, I stopped as I did not want to waste anymore reagent.
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,560
Houston, Texas
Thanks for following up on this. We can keep an eye out in case someone else gets a mislabeled batch from Puritech.
 
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