Shock or not?

[johnfam21]

Hi, we recently had a gathering with about 15 people in the pool for many hours. I’ve been reading on past forums of shocking the pool (after the fact). I ran the pump during the party and for 24 hours afterwards. I tested the pool the next morning and besides needing to add some muriatic acid, all other values looked good. Is there a need to still shock the pool? Excuse my ignorance, it’s our first pool and season so learning this as we go. Here are my results from the testing using the TF-100 test kit. Of note, my free chlorine has been high and I’ve been waiting for it to decrease over time.
Free Chlorine: 17.5 (previous 21)
Combined Chlorine: 0.5 (previous 0)
pH: 8.2
Total Alkalinity: 70
Calcium Hardness: 500
CYA: 95
Salt: 3200
Temperature: 84°F
CSI: 0.36

 

[Jimrahbe]

John,

With a CYA of 100, your FC target is 7 to 13 ppm..

As long as your FC is at your target or higher, I see no reason to shock anything...

Although I am shocked that your CYA is 100...

Thanks,

Jim R.

 

[wireform]

Well let's slow down, 95 is really 100 as @Jimrahbe. I'd recommend a diluted CYA test to be sure you're at 100 and only then can you know the FC safe level. For now just up the FC to 25 or there about because slam for 100 is in the high 30's so it's safe.

 

[johnfam21]

I added Cyarinic acid when opening the pool slowly with intermittent testing. I may have slightly overshot. How do I do a diluted CYA test?

I forgot to mention that I do run the pump daily for 5 hours or so with the SWG at 50%. I am not sure if that would be contributing to my elevated FC.

 

[wireform]

Water Testing Instructions - Further Reading

 

[johnfam21]

Water Testing Instructions - Further Reading

Thank you. I’ll retest CYA today and try the diluted test.

 

[CreedenceTapes]

Thank you. I’ll retest CYA today and try the diluted test.

Note that, if your pool gets enough sun, it will slowly lose CYA. I can't speak to Pennsylvania's latitude, but from my very sky-exposed pool in the Tampa Bay Area, the sun cooks off a good 15 ppm of CYA each month in the summer.

 

[pjt]

my free chlorine has been high and I’ve been waiting for it to decrease over time.

Turn your SWCG off for a couple days and let the FC drift down, then retest and adjust your SWCG output.

 

[johnfam21]

Well let's slow down, 95 is really 100 as @Jimrahbe. I'd recommend a diluted CYA test to be sure you're at 100 and only then can you know the FC safe level. For now just up the FC to 25 or there about because slam for 100 is in the high 30's so it's safe.

So I must have not been doing that CYA test well. I read through what you sent and retested. I think my real CYA is 70. I think I was reading it previously when the black dot started to really fade but not completely go away.