Best practices for measuring CYA?

bostonpool

Well-known member
May 29, 2017
80
Worcester, MA
Hi folks:

I'm struggling with measuring CYA. I've got the TF Test Kit and am using the squirt bottle into the graduated cylinder until the dot disappears.

Yesterday I got 80ish. Today 60ish. Nothing is different.

How do you guys ensure consistency? Also are you holding the cylinder from the bottom or the top? i.e. is the "dot" at the bottom of the cylinder at your waist, or is the top of the cylinder at your waist?

I'm struggling to hold FC this year. I haven't gotten too low, but every time I add in more chlorine I seem to drift back down to 4.5 in a day or so. I'd like to be upwards of 6. I'm wondering if lack of CYA is to blame.

What's the best way to ensure consistency? I find this test to be very prone to human error.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
11,260
Northern NJ
Consider getting CYA 50 standard solution Standard Solutions You can then practice and see what CYA 50 looks like.

I don't sweat over CYA 60 vs 80 with a SWG. It is not like you have a CYA of 30 or 40 which would be a problem. 60 vs. 80 means a FC target of 4 vs. 6. I can't control my SWG that precisely anyway.

I don't think your CYA is why you can't get your FC up to 6. How long do you run your SWG and pump? What settings are your SWG?
 

bostonpool

Well-known member
May 29, 2017
80
Worcester, MA
I'm running the pump 12 hours a day (8 AM to 8 PM). Last year I was able to keep SWG at 20% and I consistently had FC of 8-9. This year I was at 20% and I'm struggling to keep FC of 4.

I upped it to 60% a few days ago and dumped in some older, liquid shock. I didn't read the FC after adding the shock, but could smell it. 2 days later back down to 4.5 FC.

Problem is I'm not sure if FC of 4.5 is good or bad. It is good if CYA is 60 but bad if 80. Grrr.
 

Catanzaro

Platinum Supporter
TFP Guide
Jul 30, 2014
3,403
Monmouth County, New Jersey
BostonPool:

Regarding your CYA testing, only perform this test every 2 weeks or once a month. With me, it is monthly, unless increasing to a certain level. I assume that it will decrease, so always base my levels on the starting CYA. When you do the test, follow the instructions carefully, and then when the black dot disappears, add 10 and stick with the number. No need to test more often.

A 20% SWG at the T-15 cell seems very low, even with a 12 hour cycle. I believe you are at 1.45 lbs. gas daily at 100%. Plug in figures in pool math and then back off the time. This may be one of the reasons why you have lower levels. The best way to figure this out is to test at 9 a.m. and then test every 3 hours over a 12 hour cycle to see where your levels are.

At 100%, for your pool, the FC increase is 5.4 ppm daily over 24 hours. If you ran the cycle for 12 hours, you would increase your FC by 2.7 ppm. A total of 20% of this is less than 1 ppm daily. Something just does not add up.

My T-9 cell for 15,000 gallons at 50% over 8 hours did not produce enough chlorine. I am at 10 hours and have increased to 70% to see how my levels are over 7 days. I will not test until the end of the week, but will check for presence of chlorine daily.

- - - Updated - - -

PS: Worked for State Mutual/Allmerica for over 10 years before they closed!
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
11,260
Northern NJ
I'm running the pump 12 hours a day (8 AM to 8 PM). Last year I was able to keep SWG at 20% and I consistently had FC of 8-9. This year I was at 20% and I'm struggling to keep FC of 4.

I upped it to 60% a few days ago and dumped in some older, liquid shock. I didn't read the FC after adding the shock, but could smell it. 2 days later back down to 4.5 FC.

Problem is I'm not sure if FC of 4.5 is good or bad. It is good if CYA is 60 but bad if 80. Grrr.
FC of 4.5 with CYA 80 is still above minimum of 4 but not at target. Pool School - Chlorine / CYA Chart

Here is the Aquarite Diagnostics Manual - https://images.inyopools.com/cloud/documents/aquarite-troubleshooting-guide.pdf and Owners Manual https://hayward-pool-assets.com/assets/documents/pools/pdf/manuals/aquarite-120-092538-RevA.pdf?fromCDN=true
What is your salt level and generating voltage and amps?