Where is my CYA going?

[amattas]

Alright, so we opened up our pool and put our usual startup chemicals in. All the chemistry looked fine (minus the alkalinity being a little low). FC: 4.2, CC: 0, PH: 7.6, TA: 42, CH: 157, CYA: 30

I had a plumbing leak that I needed to get fixed, they fixed it when I was out of town, and my wife didn't know she had to start it all up again, so the pool sat for a week, not running, and got pretty gross.

I came home, started everything up, SLAM'd it, and thought everything was good after it cleared up. A couple of days later, it got cloudy again, so I tested my chemicals, and they were way different: FC: .2, CC: 0, PH: 7.4, TA: 79, CH: 68, CYA: 5

I wasn't sure if the CYA number was accurate or if something else was causing it to be low (I know the test kit was okay because my hot tub was reading the correct numbers), so I added enough CYA to bring it back up to about 25, and tested it 12 hours later: FC: 1.21, CC: .37, PH: 7.3, TA: 82, CH: 75, CYA: 21

Since it still didn't seemingly kill everything, I SLAM'd it again and tested it in the morning: FC: 7.13, CC: .46, PH: 7.4, TA: 82, CH: 198, CYA: 11. Yes, Hardness went back up - probably some from the shock - and CYA is low again.

So I added more CYA to bring the levels up again, and SLAM'd it again and checked again this morning. FC: 7.89, CC: 1.23, PH: 7.4, TA: 83, CH: 221, CYA: 33

CYA seems steady now, but CCL is still high, so I slammed it again this morning. I'm using the TFP app to calculate the SLAM, and basing it on what the CYA should be, so I'm likely putting more chlorine in than needed, but I'm still battling this.

Any idea what's going on? Why is hardness coming up so drastically, and what is eating my CYA?

 

[Texas Splash]

So you have a couple things working against you right now:
1 - Your test results doesn't appear to be from a TF-100 or Taylor K-2006C. If you aren't testing with one of those, you'll struggle.
2 - It doesn't appear you are following the SLAM Process page process axactly as written. I would go back there and review the instructions and ensure you perform the SLAM until you pass all 3 SLAM criteria. Very important for success.

Accurate testing and following the SLAM Process are key. If you have any questions about those let us know.

 

[amattas]

You are correct. It's not a TF-100 or Talor K-2006C. I have a Lamotte SpinTouch (that's been calibrated), so the numbers should be accurate. I went back through the calibration process and part of it to make sure that wasn't an issue. I used to have a Taylor-2006c, and the calibrated Lamotte was consistent with the results I got from that test kit, so I opted for ease of use (I have terrible vision and always struggled with the color gradients). I do still have the K-2006C kit, but I believe the reagents have since expired.

I will go back through the SLAM procedure, although I'm still unclear on what would cause CYA to go away. I thought the only way you could remove it was through draining and refilling. Any thoughts there?

 

[mknauss]

Any thoughts there?

Test Error.
Water exchange.
Bacteria. Ammonia will result that will give low pH and high CC.

 

[amattas]

Test Error.
Water exchange.
Bacteria. Ammonia will result that will give low pH and high CC.

Probably not a test error, that was my first thought, and I opened a new pack of disks. I'll go pick up new reagents this afternoon, though, and double-check.

I did add water once with the leak. It was about 500 gallons, but I haven't added any since so probably not enough to drop from a CYA of 30 to a CYA of 5. Our city water also typically has a PH of 7.8-8.0, so adding water usually creates a PH rise for me.

Bacteria might be possible; the PH had gradually dropped from 7.6 to 7.4 with no acid added (and higher PH city water). Does that seem in the proper range for that reaction? Is there any way to test for Ammonia, or does it evaporate off?

 

[PoolStored]

Bacteria might be possible; the PH had gradually dropped from 7.6 to 7.4 with no acid added (and higher PH city water). Does that seem in the proper range for that reaction? Is there any way to test for Ammonia, or does it evaporate off?

Here is how to test for ammonia:

Ammonia - Further Reading

www.troublefreepool.com

 

[amattas]

Thanks! So I've been at least mostly on the right track, I just haven't finished the last step with SLAM to with the overnight loss test and the clarity part.