Believe the SWG or test kit?

[roguegeek]

My SWG is reading salt at 3600 ppm. My K-1766 is reading it at 4000 ppm. I feel like that is a large discrepancy, but I've been told that is within the margin of error. What reading should I go by to make further decisions on balancing my water?

 

[Divin Dave]

Those levels are within the margin of error for salt. But since you are itchy about it.....
The SWG has a min and max level for salt, so use the highest value to make sure you dont go over the recommended max.

 

[pooldv]

Salt tests and sensors in SWGs have a margin of error of +/- up to 400 ppm. To further complicate things the salt test measures a different component than the SWG sensor measures. The salt cell will also be subject to temperature causing it to read lower as the water temp drops. All of these things are only really designed to help you keep the salt level in a range where the cell will operate properly and make chlorine. If the cell isn't giving a a high or low salt error and you feel you are within the range of salt needed for the SWG then you are good to go. I know that my cell will operate fine with no error lights with salt between 2800 ppm and 4500 ppm. So anywhere from 3000 to 4000 ppm is right in the middle.

 

[Isaac-1]

As the others have said it is within the margin of error, remember the SWG is really measuring the electro-conductivity of the water which it assumes is solely related to amount of salt in the water and the salt test is chemically measuring the salt level.

 

[JoyfulNoise]

Typical SWG failure modes are for the cell plates to scale with calcium or for the coating to wear away on the plates. Having the independent salt test (K-1766) enables you to diagnose those failures as they will manifest as a low salinity reading on the SWG when the K-1766 is reading normal.

 

[roguegeek]

Ok, so the ProLogic documentation is telling me operating salt level is between 2700-3400 ppm with 3200 ppm being optimal. The Water Balance for SWG article is stating I should start start out 200-400 ppm higher than the ideal recommended level. Using this logic, my target is going to be 3400-3600 ppm. Using this and the current state of 3700 ppm (what the SWG is reading right now), I'll take the steps being told to me by PoolMath to get my salt levels where they need to be. After that, I'll be following the rest of the Water Balance article. Does that rationale seem sound?

Separate, but related, question. Every once in a while I will find the ProLogic showing "Chlorinator off, percentage met" with no "Check Status" light on. I'm guessing this means it's hit the chlorinator percentage (currently set at 50%) and is waiting to turn back on at some time when it's needed again?

 

[JamesW]

Percentage met is normal. Don't raise the salt over 3,000 if pool is going to be heated. Hot water makes the SWG work much better. Actually, too good. The amps can get high enough to trip the high amps warning and shutdown.

 

[firstbase]

I don't know much but will chip in on what I have been told. I have a Hayward salt cell that is 10 years old. Been told thats a really good run for a cell.As they get older they drop in salt reading. Right now mine says 2700 when my salt test says 3200. Thats a little out of the maring of error and I, right orwrong, attribute it to the age of the cell. It still makes chlorine even though it tells me "Low Salt". I think I am good down to about 2600 before it gets whacked out. I check the readings on amps and volts and such that it shows and they are within the range they should be. So... I let it keep on ticking. Don't know if this helps....

 

[Isaac-1]

The water balance for SWG article was written assuming you live in a location where there is significant rainfall which will dilute the pool water with salt free water. If you live in an arid location you should not over shoot salt levels as they will likely naturally build up if you have salt in your fill water (most places do)