Salt cell or motherboard?

[lazybonz]

Living in new home with pool that was installed 7 years ago. Began managing pool last year with TFtestkit and TFP method. Through last years experience and recent observations I feel like something's not right with the salt system.

Last year, maintaining CYA at 80, the SWG was able to maintain FC with 6 hrs a day run time and SWG set at 15-20%. Salt reading was routinely 200-400 ppm lower on SWG display vs test results.

This year, I'm running pump 24/7, with SWG set @ 50% to maintain FC. CYA is still 80. The salt reading is 1000 ppm lower than test results. I'm having to reset the instant salt reading daily to avoid low salt alarm, and keep the SWG generating. Also as an aside, got a new K-1766 kit. Using last years remnants vs the new kit, there have been times where the kits disagreed by as much as 400 ppm. I'm trusting the fresh kit more.

Have been looking for more info on troubleshooting. I have done the re soldering trick once last year. It seems something is going bad, but I don't know how to definitively nail down which part. Through past experiences I have little faith in either the competence or trustworthiness of my local pool stores. Would like a diy fix. Any thoughts?

 

[JasonLion]

There are three possibilities I can think of. First, if the water is below 70 degrees the SWG won't work as well as it does at warmer water temperatures. Second, you should visually inspect the cell plates for calcium scaling. The plates should be clean and free of any chalky residue. Third, cells do wear out eventually. Typical lifetime is three to five years, but it can vary from that. The symptoms you describe match the symptoms of a cell that is wearing out.

 

[lazybonz]

If I take the cell to a pool shop for them to test, what feedback tells whether the cell is good or bad? I assume it has to be an electric readout (measurable data point)?

 

[JasonLion]

Pool stores give you a simple good/bad test result. They can't tell you how much lifetime is left in the cell. Cells fail over one to three months, slowly losing function. If you add way too much salt you can keep them going a little longer.

Yes, they use an electrical readout of resistance between the cell plates at a known salt level and temperature.