Weird stuff going on with my CYA

zethacat

LifeTime Supporter
#1
Last CYA test was on 10/22 and it was maybe 38. I put 1 lb of HTH granular stabilizer into a sock on Sunday, which completely dissolved by the end of the day. Today I just tested CYA and it is 35. ??????????????????? Did I get a bum jug of stabilizer? :confused:
 

pooladdict

TFP Guide
In The Industry
May 15, 2007
819
New Brunswick Canada
#2
Not sure how you tested, but I believe readings only are in increments of ten, make sure you use the same sunlight and the same angle every time

Cya can take up to a week to give a reading, try it on the weekend.
 

zethacat

LifeTime Supporter
#3
I used the tube with the black dot, of course. I know it only shows increments of ten but there's a pretty big gap between 30 & 40. If I stop seeing the black dot somewhere in between, shouldn't I guesstimate or should I round up or down? I squeeze a little bit out of the bottle at a time until I can't see the dot anymore, and I always do it in the same spot in my kitchen while holding the tube waste high and looking straight down. If I can see the dot even the smallest amount, I squeeze a little more in until the dot is completely unnoticeable. Should it really take a week to show up if it completely dissolved from the sock?
 

Kiss4aFrog

LifeTime Supporter
TFP Guide
May 22, 2013
2,723
Hudson, WI
#4
You can guesstimate if you'd like ;)

If you are doing it in your kitchen :confused: you aren't doing it out in the sun with your back to it (the sun) as is recommended. You results won't be as accurate but it's like rounding up or down. As long as you are doing the same thing the same way each time you have a standard and the results should be repeatable. Your reading might not be as accurate compared to the actual physical CYA concentration as out in the sun but if it's repeatable and you are at a level that protects your chlorine from being burned off ... you're good.

How to test CYA : https://www.youtube.com/watch?v=NxaqoW-_MCs

It can take a week from the time the CYA is completely dissolved for it to show up so wait till Sunday or better yet Monday until you retest.
 

JamesW

TFP Expert
Mar 3, 2011
12,676
#5
1b. will raise the cyanuric acid by about 9 ppm. Your results could be consistent within the accuracy/precision of the tests.

If your first test read high by 4.5 and your second test read low by 4.5, then that could explain the results.

In any case, cyanuric testing can be one of the most difficult to get good precision/accuracy.

Also, if you had any rain, or if you added water, then that would lower the cyanuric acid level.
 

zethacat

LifeTime Supporter
#6
You can guesstimate if you'd like ;)

If you are doing it in your kitchen :confused: you aren't doing it out in the sun with your back to it (the sun) as is recommended. You results won't be as accurate but it's like rounding up or down. As long as you are doing the same thing the same way each time you have a standard and the results should be repeatable. Your reading might not be as accurate compared to the actual physical CYA concentration as out in the sun but if it's repeatable and you are at a level that protects your chlorine from being burned off ... you're good.

How to test CYA : http://www.troublefreepool.com/content/165-getting-started

It can take a week from the time the CYA is completely dissolved for it to show up so wait till Sunday or better yet Monday until you retest.
I have a pretty bright light in the kitchen, and I always do the test in the same spot. I always do all my testing and chemical adding at night, but I'll try doing it tomorrow in the daylight facing away from the sun and I'll let you know if the results are any different. I've been adding a little over a quart of 8.25 each day. I've been going with a target FC of 8 since my target CYA is 50. Does that sound about right for a pool my size?

Your link on how to test CYA did not bring me to a page that tells me how to test CYA, though I know how to do it, and I've seen the back to the sun recommendation in the extended test kit directions. The laminated instruction sheet that comes with the TF-100 does not say anything about doing it outside though.
 

pwrstrk

TFP Expert
LifeTime Supporter
Aug 18, 2012
4,758
Elverson Pa.
#9
Your correct. Target an FC level of 8 and never let it fall below 4 if your CYA level is 50. Adding little over a quart of bleach sounds about right to me. That's basically what I avg adding in my pool and our water volume is almost the same. 😎
 

zethacat

LifeTime Supporter
#11
Well I guess you can say "I told you so" .. for some reason I can see the black dot for a little bit longer when measuring CYA in my kitchen. According to my back to the sun method, it's at 45.. but inside the house it's closer to 40. Hmph. In any case, I hope it goes up to 50 by Sunday because that's where I want it to be. And I had to order another bottle of R13.. I've done so many CYA tests already lol.
 

pwrstrk

TFP Expert
LifeTime Supporter
Aug 18, 2012
4,758
Elverson Pa.
#12
Don't forget the test has an error factor of plus or minus 10 ppm. So if it stays at 45 call it 50. I like to round up so your covered with the FC range. 😎
 

Kiss4aFrog

LifeTime Supporter
TFP Guide
May 22, 2013
2,723
Hudson, WI
#13
Do you know that you can pour it back and forth and do the test a couple times with the same water just to "test" yourself and see if you are consistent in your reading ??
 

zethacat

LifeTime Supporter
#15
I didn't know that the first 25 times I tested CYA, so I used up all my reagent lol. I actually just learned about that today. I think I'm happy with where it is now though. I only had to add exactly 1 quart tonight but my PH keeps drifting up with a TA of 80. Maybe it's the new plaster ... I would prefer the PH drift downward, because I can leave the waterfall running to raise it back up. Would a lower TA cause the PH to drift down?
 

pooladdict

TFP Guide
In The Industry
May 15, 2007
819
New Brunswick Canada
#16
Normally with a Salt water pool we like the TA to be lower then standard, it helps to keep the Ph in check, I do know that some pools like to settle at a certain Ph and are stubborn to move to another number.

If you are seeing no scaling or anything of consequence, then perhaps leave it a tad high for a short period of time, check regularly and see where it goes to.
 

ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
2,923
Long Beach, CA
#17
The plaster is new so you will be experiencing raising pH for about a year due to the plaster going through the curing process. You will need to add acid often to keep the pH in the 7's and I expect by next winter you will see a significant drop in the amount of acid you will be using.

The only way the pH will lower is if you add an acidic component to the water. Tabs, acid, acidic fill water are the some of the things that will lower the pH.

A lower TA will not make the pH lower itself. The low TA can help stabilize the pH for longer periods of time but you need to make sure the water is balanced and not too acidic or the plaster will be etched from the acidic water.

Post a full complement of test results and we might be able to offer a little more advice if anything else can be done.
 

zethacat

LifeTime Supporter
#18
FC 8
CC 0
PH 7.5
TA 80
CH 250
CYA 50

The avg temp here past few days is 65. The PH drifts up about every other day and I was allowing it to get to 8 then bringing it down to 7.5 but the past week I've been bringing it down to 7.5 once it hits 7.8. Pool math says 7.8 is my sweet spot so maybe I should continue letting it get to 8 before I add acid. I was just doing a little more reading and I haven't been diluting the acid before pouring it in front of a return, though I've been doing it pretty slowly and only adding small amounts to begin with... I will start diluting it first as I don't want any etching.
 

ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
2,923
Long Beach, CA
#20
I would not let the pH rise above 7.8 as that is the high limit of the test and when it gets above that you just don't know how high it really is. For now you will just have to keep adding acid to maintain the pH. The numbers look good so you just will have to deal with the rising pH as required.