CYA Decreased After SLAM

[Van G]

Had to SLAM our pool last week due to SWGC being dirty and not producing enough chlorine + roookie mistake on not adding bleach after a few big parties...

Anyway, coming down from SLAM at 24 PPM:

FC 8
CC .5
PH 7.4
CH 100
CYA 35
TA 90
Salt 1800

Everything is where I thought it would be but CYA, which was 60 when pre-slam.

I did just add a few inches of water and let it mix for an hour.

Would a SLAM burn off CYA?

 

[mknauss]

CYA can degrade some naturally. Elevated water temperatures accelerates it a bit.

Your CYA test is 40 ppm (round up). The test is at best a +/-10 ppm accuracy. How long ago did you measure the 60 ppm?

 

[jblizzle]

Increased FC levels can lead to the CYA breaking down more quickly, but it would not think it would be 25ppm in a matter of a week.

Typical degradation due to hot sunny summer dats is like 5-10ppm in a month.

 

[Van G]

It was 60 ppm 2 weeks ago.

I’ll test again this morning.

What is the shelf life of liquid cyanuric acid? Wal-mart sells it in gallon jug and it would seem to be the more efficient way to go if It stays good for a season or more.

 

[mknauss]

The liquid conditioner will stay effective for more than one season. It can settle in the bottle so it is best to use the entire bottle when you need it.

 

[Van G]

CYA was 45 this morning. Tough test to get the hang of!

We had a good rain this afternoon which added a few inches to the pool so i’ll test again and add some stabilizer tomorrow.

Side question: after a pool party or after a rain storm, how much chlorine do you add to help the SWGC out? 1L/10K Gal

 

[IceShadow]

Take it up a few extra ppm and you should be fine.

BTW, the scale isn’t linear, so if it’s between two levels just round it up. Use 50ppm for your CYA calcs.

 

[mknauss]

We don't get much rain.....

Pool party, add 5 ppm FC before and test after.

 

[Patrickoleary]

I have a similar experience I posted in a thread recently. I was around 70, dropped to 50, added liquid, added granules, was up to 70, back down to 60. All in a couple weeks. Perhaps the accuracy of the test isn't that good anyways and I shouldn't worry about it.