Attempting to SLAM

[Jbrillo]

I checked my FC this afternoon and it was at 1.5ppm and I had CC of 1.5ppm and my pH was 7.5(via my TF-100). It’s the first time I’ve ever seen my CC greater than 0.5ppm.

We had a storm 2-days ago and I had to drain about 4-niches of water to keep it from overflowing(no overflow lines here). I didn’t do a full chemistry check b/c this has happened a few times before and it’s never affected my chemistry. My FC after the storm was 5ppm so I thought I was good. The family swam yesterday but I had to work so I didn’t check my water till today and nearly panicked to see a CC of 1.5ppm. Water is still crystal clear.

I had to go back to work tonight so I didn’t have time to do a full chemistry test. I did have time to drop in 3-gallons of liquid chlorine. I had my wife test the chlorine level when it got dark so I could do an OCLT. FC was at 20ppm and CC was 1.0ppm. I will check it in the morning when I get home.

I’ve been pondering what could’ve gone wrong and then it hit me.......this is the second time I’ve drained 4-5inches of water in a week. We had a storm last week and I drained it. FC levels had been fine since last week then 2-days ago I had to drain another 4-5inches and two days later my FC is 1.5ppm. I assume when I can test everything in the morning I think my CYA may have dropped a lot. At least I hope that’s my problem and not my brand new SWG malfunctioning. What do you guys think?

(I know I needed full tests, I just was in a time crunch and I panicked seeing a CC of 1.5. I know 20ppm isn’t quite SLAM level but I’m hoping it’ll be ok till I get home in the morning).

 

[Teald024]

I don't think the drain from rain had much to do with it. Granted the CYA probably went down some, but it shouldn't be too drastic, id guess it dropped by 10-15ppm.
It's possible that the storm or family dragged in some heavier organic load. a CC of 1.5 is high, but it looks like it dropped to 1 in a few hours and may have gone back to normal levels by the time you test in the morning.
I wouldn't panic just yet. Keep an eye on it and add some extra chlorine like you did.
I think it's a bit premature to panic about the SWG. Test the salt level and see if the "low salt" light is on. If you were borderline low on salt, the extra rain & drain may have been enough to pause the SWG from turning on.
Test results of concern are FC, CC, CYA and salt. Others don't matter for this issue.

 

[Jbrillo]

I will keep an eye on it and I’ll post my results as soon as I get home to test it. My SWG says salt is 3000. It was 3400 last week. Then I had to drain and it went to 3200. After draining from this weeks storm, it went to 3000. Seems to be pretty consistent when I have to drain. I think the SWG is ok I assume it’s more CYA related. Since my pool is new, I slowly worked my way up to a CYA of 70. I noticed it burned chlorine a lot faster when my CYA was 60 than when I bumped it up to 70. At 70, I was able to turn my SWG from 45% to 40% to maintain a FC of 6. If my CYA has dropped to 60 or even 50, I could see how 2-days of full sun and a lot of people in the water could drop FC from 5 to 1.5. I guess we’ll see what happens when I test this morning. It just got really scared when I started adding the R-0003 and it immediately turned dark purple. I’d never seen that happen before.

 

[duraleigh]

As Teald024 says above, swimmer load likely had more to do with your FC drop than anything else.

Dilution from rainwater is pretty easy to predict. You twice drained 4 inches from a pool that, on average, is about 4 feet deep. That's a total of 8 inches in a 48 inch pool so you diluted (with the rain) about 16%. The actual dilution is a little less than that but that it gives you an idea that the chemistry in your pool is about 85% of what it was before the drain. Lot's of variables there......don't overthink that calculation just be aware that rain, even as heavy as yours was, has little influence on your pool chemistry

 

[Jbrillo]

Thanks Dave! I like the calculation! Makes a lot more sense that way.

So here are my morning results:
FC 18(dropped from 20 last night)
CC 0.5
CH 275(dropped from 300 at last test)
TA 90(same as last test)
CYA 60(dropped from 70 at last test)
****The black dot disappeared between 50 and 60 but IIRC that means round up to 60????***

So, my water is clear, CC is normal, but my FC dropped by 2ppm. Do I need to maintain a high level or do you think it’s safe to let it drift back down?

 

[Teald024]

Keep it high for today and do another OCLT Sunday night to see where you’re at.

 

[Jbrillo]

Will do! Thanks for yalls input!