My post-Ida salt level doesn't make sense

[riny]

Well we got about 6.5" inches of rain here, not as bad as many people but still enough to make the pool overflow. I ran the SWG for extra time before the storm to pre-emptively raise the FC level and that seems to have worked. Now all of my numbers make sense... except the salt level. My CYA and borate levels are exactly the same as the previous test about 2 weeks ago but somehow I seem to have lost a LOT of salt. Here are today's readings:

FC 11
pH 8
TA 60
CYA 70
Salt 2200
Bor 48

The salt level was 3200 when I last tested it. I did the drop test twice to be sure and it took 11 drops each time to get to brick red. Then I took another sample from a different part of the pool and it took 12. If there was enough water replacement to drop the salt by 800-1000ppm, shouldn't I have lost a lot of CYA and/or borates as well?

The other weird thing is that my SWG is still happily generating. It hasn't given me a low-salt message. I would have expected an error under 2500, but I've heard that might not be totally reliable.

I can add some salt but before I do that, I'm looking for a sanity check. Is it possible that I lost salt and nothing else? Or could something be causing an incorrect reading?

 

[ajw22]

Don't add any salt. Your water stratified with the rain water on top of the heavier salt water. Give it a day or two for the pool water to mix. If you have a VS pump crank up the speed.

How are you testing the salinity to get that 2200 Ron? You are testing the rain water with higher salt water deeper down.

 

[riny]

Ah that makes sense. My method has always been: small plastic container, hold it upside down, plunge it in about 12" (just shy of elbow deep), flip and raise. Then I bring it inside and test from there.

That also explains why I got a slightly higher reading with the second sample. I probably went a little deeper. I'll do as you suggest, run the pump on higher speed for a few days and then retest. Many thanks, that's exactly what I needed.

 

[Bvacchiano]

I personally don’t see why this can’t be. We get that type of rain all the time down here Houston and can easily lose 1000 ppm. I mean think about how much rain water that is. I always keep my salt around 4100 ppm (what my SWG says) for these exact exact instances so that if for something reason I’m not home my SWG won’t quit generating chlorine.

 

[mknauss]

I'll do as you suggest, run the pump on higher speed for a few days and then retest.

Run the robot. It will mix things up to.

 

[riny]

I personally don’t see why this can’t be. We get that type of rain all the time down here Houston and can easily lose 1000 ppm. I mean think about how much rain water that is.

I would have believed it if I'd also lost 1/4 of my CYA and borates. With ONLY my salt level being down, I got suspicious.

My normal water level is maybe 4" below the coping so while the pool did overflow, I should only have had 2-2.5" of spillover. And hopefully that was mostly rainwater that just went straight to the overflow without mixing. Even 2" of full water replacement is only 4% of my pool volume so I didn't understand where all of that salt went. It makes more sense for it to have gown down rather than out.

 

[Newdude]

Hey riny !! At most you gained 13% fresh water which would lose 433 ppm of salt. Like you mentioned above, some had to go straight to drain / overflow. So once you mix it up you will be under a 400 ppm loss. It also explains why you don’t see the CYA loss as it’s less than 10 which is iffy to see and rounds up *if* you can tell the difference.