Salt Levels

[cschnurr]

I have an AquaRite SWG installed in 2005. The recommended salt level is 3200pm, recommended CYA level is 60-80ppm
I have always found the salt level reading to be fairly accurate when compared to my strip testing.

This year started opening my pool during a particularly warm March, wishing that it would continue.
My salt reading was 2000ppm (which is typical since I have to drain much water out of the pool during closing in the fall)
The water temperature was just below 50F.

I added the 100kg of salt necessary to increase to 3000ppm.
After a couple days, the display on the unit read 3100ppm as expected.
Water temperature was still around 50F.

I then added CYA through the skimmer to bring it into range.
During this time the salt reading increased dramatically to 5100ppm, and I don't understand why.

I have a couple theories I would like your comments on
1) The SWG does not operate below 50F, and the salt reading may not have been accurate at this temperature.
Even though this is typical of the amount of salt I've added previous years.

2) My SWG may be near its end of life?

3) Adding CYA somehow affected my salt reading?

The temp is now around 65F and the SWG is generating as measured by chlorine in the pool, and the salt level is 5100, the Voltage and current are within the operating limits, and the High Salt indicator is not illuminated. Obviously I need to get some test strips to validate the readout, but does anyone have an explanation why it jumped so dramatically. Assuming it is accurate I have options
a) operate SWG with high salt level
b) turn the SWG off and chlorinate with liquid for a while until the salt level drops to range.
c) Drain and refill to dilute the water.
Any suggestions

 

[JasonLion]

Your unit is certainly old enough to be nearing the end of it's life. However, an old failing cell will report the salt level as being lower than actual rather than higher.

Cold water tends to cause a lower than actual salt reading.

There isn't any reason for CYA to affect the salt reading.

I suggest leaving everything as is as long as the SWG continues to produce chlorine normally. The salt level will come down very slowly over the course of the season. Salt levels up to 5000ish are fine as long as the SWG doesn't give high salt error messages.

It would be interesting to get an independent check of the salt level. If an independent check shows that the salt level really is 5000ish, then you will know not to add any additional salt next spring. While if the salt level is actually more like 3000 you will know that the SWG is starting to fail in some nonstandard way. But either way there really isn't anything that can or should be done about it right now.