Brand new salt cell reading 600 ppm below Taylor test...should I care?

[PointeTaken]

I replaced my cell a couple of weeks ago with a brand new one. Right after I installed it, the K-1766 test (also a brand new replacement) indicated 2200 ppm, which was identical to the reading I was getting from the SWG. I shut it off, added 100 lbs. of salt, and 24 hours after turning my SWG back on, it was reading 2700. The Taylor test was giving me a readout of 3200 ppm, which is exactly where I'd expect it to be based on the salt added. I tried the recalibration method that both Hayward and people on this forum have recommended: turn off SWG, turn back on, press diagnostic button 5 times, wait for 'click' and then momentarily push switch up to superchlorinate when the instant reading lands close to the expected value. The highest choice it ever gave me was 2700, so that's where I calibrated it. It has continued to give me a reading of 2700 since, until last night when it gave me a reading of 2600. A subsequent K-1766 test - performed three times - this morning yielded the same 3200 ppm. This deviation (and the SWG behavior) is considerably different than when the old cell was installed, even as it was nearing end-of-life. I know it's generally accepted that the margin of error is about +/- 400 ppm for both the SWG and the Taylor test, and so with compounding error, the difference could very well be within the margin of error, but it still feels "off" to me. What's especially troublesome is that the SWG is showing declining salinity despite zero water replacement in two weeks.

So...is there cause for concern? Or should I just feed it the additional salt that it wants to keep it happy and not worry about it?

***EDIT to add additional info for reference:

Water temp: 74
Product name set to AL-6

 

[JamesW]

Move the switch from auto to off and check all of the readings.

Move the switch back to auto and recheck the readings.

Move the switch to off for a minute and then back to auto and recheck the readings.

Report all readings.

What are the first seven characters of the cell and box serial numbers?

Is the cell a genuine Hayward T-5?

 

[Newdude]

Is it working and just telling you it’s low ? Or is it not working because it’s reading a low ?

 

[PointeTaken]

Move the switch from auto to off and check all of the readings.

Move the switch back to auto and recheck the readings.

Move the switch to off for a minute and then back to auto and recheck the readings.

Report all readings.

What are the first seven characters of the cell and box serial numbers?

Is the cell a genuine Hayward T-5?

I will do that and report back shortly.

It sure as heck better be. Bought it from Inyo last month.

 

[PointeTaken]

Is it working and just telling you it’s low ? Or is it not working because it’s reading a low ?

It's generating, but since it dropped below 2700 it is throwing check salt and inspect cell warnings, and thus I assume it is operating at reduced efficiency.

 

[PointeTaken]

The average salinity has since gone back up to 2700. Here is my reporting of readings:

Move the switch from auto to off and check all of the readings.
2700
74
31.9
0.00
29P
- 0
AL-6
r 1.47

Move the switch back to auto and recheck the readings.
2700
74
27.9
3.61
28P
-2700
AL-6
r 1.47

Move the switch to off for a minute and then back to auto and recheck the readings.
2700
74
27.9
3.56
29P
-2600
AL-6
r 1.47

First 7 digits of the box are 1A18157
First 7 of the cell are 3E20269

 

[JamesW]

It looks like it's working.

The salinity is a little bit low, but within the margin of error.

Check the salinity a few different ways to be really sure.

Your original cell should have been within the 3 year warranty period from when you bought it.

Did you try to get a warranty cell?

 

[PointeTaken]

It looks like it's working.

The salinity is a little bit low, but within the margin of error.

Check the salinity a few different ways to be really sure.

Your original cell should have been within the 3 year warranty period from when you bought it.

Did you try to get a warranty cell?

No, the previous owner reported buying the cell in 2016. I take it the serial number says otherwise? Sigh...

What are some other reliable ways to test salinity?

 

[JamesW]

First 7 digits of the box are 1A18157

The box is from the 157th day of 2018 (June 06 2018 Wednesday).

What is the serial number from the original cell?

 

[JamesW]

What are some other reliable ways to test salinity?

Try a digital meter and a different drop test kit.

 

[PointeTaken]

Oh, duh. I gave you the new cell serial number. Brain fart.

3F18150 is the old cell. So May 30 of 2018? And still under warranty?
None of this jives with what the owner left me in his notes. He reported replacing the original Mineral Springs system with the current Hayward unit in about 2012. Poor memory, it would seem.

 

[JamesW]

3F18150 is the old cell. So May 30 of 2018? And still under warranty?

Yes. Take it to a store that tests cells, and if it fails, they should give you a new cell.

Bring a water sample to have the salinity tested.

The first number (3) is the number of years for the warranty.

The letter should be E and not F.

 

[PointeTaken]

Well, I took a sample to two stores, both came back with 2700 ppm using a meter. So, given three readings of 2700 vs. 3200 on the drop test, so I’m thinking the drop test is the one that’s off by the greatest margin. Pretty sure my testing method is sound, so either the margin of error really is that high or my reagents are no good. I think I might create a calibration solution and do the drop test to see how far off it is. I also went ahead and ordered a digital testing meter as a comparative method to have on hand.

Neither store tests salt cells.

 

[JamesW]

Dealer Locator

Locate a dealer near you for all your needs: building or servicing your pool, buying a product, or warranty support.

www.hayward-pool.com

Maybe mail the old cell back to Hayward to have them test it if they will accept that.

How did you determine that the old cell was bad?

Maybe file a warranty claim and ask Hayward to send you a new cell.

If they want to test the cell, they can figure out a way to do it.

 

[Newdude]

So, given three readings of 2700 vs. 3200 on the drop test, so I’m thinking the drop test is the one that’s off by the greatest margin

Probably the only thing that sucks about salt is the +/- 200 accepted margin for error. Your own testing can be from 2800 to 3200 and be correct. When you compare with another slightly less accurate method it can vary even more. You test high at +200 and the store tests low on their range at -300. And you’re both right.

Wherever the true level is, it seems to be dancing the low threshold for where your cell wants to work. I’d add 100-200 ppm and monitor the cell to verify it’s happy.

Before TFP I didn’t even know there was a test kit. If the cell complained I added a bag and it shut up. Then we both happily went about our way.

 

[PointeTaken]

I’d add 100-200 ppm and monitor the cell to verify it’s happy.

Yeah, I'm going to add half a bag in the morning once it stops raining and see how we're looking.

 

[PointeTaken]

How did you determine that the old cell was bad?

"Check salt" and "inspect cell" were illuminated and wouldn't stay off, despite inspecting the cell, cleaning it, and keeping the salt level above 3000. Zero chlorine production. Cell voltage was also well out of spec. I don't recall the exact number.

 

[Pool_Medic]

How can it be a new cell with 2018 in the serial #?

 

[JamesW]

First 7 of the (new) cell are 3E20269

3E18150 is the old cell.

How can it be a new cell with 2018 in the serial #?

 

[JamesW]

Put the old cell back in and do this procedure again.

Move the switch from auto to off and check all of the readings.

Move the switch back to auto and recheck the readings.

Move the switch to off for a minute and then back to auto and recheck the readings.

Report all readings.