Does adding Salt really spike the level on the SWG sensor even hours later?

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Wolfepack88

Wolfepack88

Gold Supporter
Jun 21, 2020
760
NJ
Pool Size
17690
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
I was at 2600ppm (per my taylor brand new salt test) and my pool math told me to add 89lbs so I just added 80lbs and now my sensor in my SWG (I have it set at 0 but I still get a salt reading) about 8 hours later is saying 4000. Per pool math it should have landed me just shy of 3200ppm. So does the dilution take that long to settle back down because no way it should be off and my water volume is dead on so hmmm?
 
I could see some salty water getting pulled into main drains for up to a day, but not in skimmer only pools. By the time it makes it from the floor to the skimmer, it's well mixed IMO.
 
How’d you add salt over the volume of the pool? Do you have the main drain kit? How was your pump running? How did you dissolve the salt? Did you agitate and brush it in? What kind of salt…water softener pellets or granules? Yes it can take a while depending on several variables.
 
If adding over one or two 40# bags, the pump should run for 24 hours after all the salt is fully dissolved before testing the salt level or using the SWG.

You stated your salt test result was 2600ppm before adding the 80 pounds. What was the SWG reading?
You stated that 8 hours later the SWG reading showed 4000ppm. What does your salt drop test read?

You're mixing two separate reading types. Mixing apples to oranges isn't going to work well.
Use your salt test and record the result. Note the SWG reported salt.
If needed, add salt.
Fully dissolve all the salt.
Pump running.
After 24 hours, test the salt again with your test kit and record the result. Note the SWG reported salt.

Was the pump running the entire time after adding? If so, what rpm?

Let the pump run for 24 hours and retest with the test kit. Report back here. Also report the SWG reading.

I tend to wait 24 hours afterthe salt is dissolved - with the pump running - anytime I add a bag or more .
 
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I had the pump running at 2700 rpm the whole time. I used Mortons premium salt and brushed it in. I did a test using Taylor and it was 2600 before adding salt and that as well as my swg reading agreed at 2600. I was going to wait until today to test again with Taylor but just did a sanity check as I woke up and the reading on my swg was 3600 so it has come down. Once I have my break it's time for the Taylor. I will report back.
 
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Personally I add a full day because there is no rush, especially this early in the season.

At 24 hours I trust its mixed enough to turn the cell back on. I'll check its guess and also test because I'm impatient but I take the results with the proverbial grain of salt. At 48 hours, I start to believe it.
 
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Tested with Taylor and I have 3600 so I'm a bit annoyed that I overshot 3200. That must mean my volume is a bit lower than what I think. So next year I will put even less than what pool math says. I had already put about 1lb less so maybe push that to like 10lbs less. interesting my SWG says 3900 where before they were both the same so I will test again in a few days after I get back from a trip.
 
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They said we have crazy rain coming Thurs night / Friday morning, plus whatever other April showers show . It'll need more soon enough.

Also, the original test may have read a little low and this one a little high and it's not as far off as you think.
 
Newdude said:
They said we have crazy rain coming Thurs night / Friday morning, plus whatever other April showers show . It'll need more soon enough.

Also, the original test may have read a little low and this one a little high and it's not as far off as you think.
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Maybe I should open my autocover and let it rain in there a bit. Hmm or I drain my built in spa and refill that with new water and do that a couple more times and that will dilute it some.
 
Your autocover certainly reduces the amount of rain diluting you, but some still gets in there. It's only a matter of time and there's no harm waiting it out.

Or you lower the salt and then need to top off the CYA and CH that also went down. It's not worth the effort IMO.
 
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Newdude said:
Your autocover certainly reduces the amount of rain diluting you, but some still gets in there. It's only a matter of time and there's no harm waiting it out.

Or you lower the salt and then need to top off the CYA and CH that also went down. It's not worth the effort IMO.
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As someone said to me last year, dip my margarita glasses in the pool water. LOL
 
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Wolfepack88 said:
Tested with Taylor and I have 3600 so I'm a bit annoyed that I overshot 3200. That must mean my volume is a bit lower than what I think. So next year I will put even less than what pool math says. I had already put about 1lb less so maybe push that to like 10lbs less. interesting my SWG says 3900 where before they were both the same so I will test again in a few days after I get back from a trip.
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The salt test has a +\- 200ppm tolerance so just be aware of that next time.
 
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Newdude said:
All Taylor tests are 1 drop variance. Then your 10ml may not have been dead on.

For the tests that need many drops, some of us factor human error in a little more too.
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It would sem that if you used 11ml of pool water, your tests could be high by 10%. Correct? I think a few times i was not precise enough when doing salt testing and results varied more than aniticipated.
 
Newdude said:
I could see some salty water getting pulled into main drains for up to a day, but not in skimmer only pools. By the time it makes it from the floor to the skimmer, it's well mixed IMO.
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I have two skimmers, deep and shallow, no main drain. I had one spike, that shut down the swg, when I added salt. It certainly was the addition of salt.
 
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