Can salt water test strips go bad?

[tnthudson]

I've got the salt water test strips that duraleigh carries, and last season the strips were spot-on with what my SWG was reading.
I had to replace the SWG cell in the off-season, so the cell could be partly to blame here, but this year, the same test strip bottle was reading 4700+ when I tested, while the SWG cell was showing Low salt (which is under 3000, if I remember correctly). I bought a new test strip bottle, and the new strip is showing 3700 or thereabouts, so that means it disagrees with the old strips by 1000 ppm.
And even though the new strips are showing 3700, the SWG cell is still showing Low, when it should be showing Good. I'm afraid my SWG (Intellichlor) may not be producing much chlorine as a result, as I'm right at 2.0 ppm CL, on the low end of the recommended level.
Any ideas?

 

[JasonLion]

Yes, the salt test strips can go bad. They will go bad very quickly if they get damp, even high humidity can do it over time, and they don't usually last much beyond then their expiration date.

 

[grumpy]

So, what was your salt reading last year? Is the new bottle of strips close to what you expected the salt level to be? If your chlorine is only 2.0 ppm, what % is your SWG set on?

There have been a number of us reporting that their fairly new intellichlor units show low salt when the test strips show the salt level to be correct.

 

[tnthudson]

I think the reading on the new strips may be correct...since I expected low salt on start-up this season, I added a couple of bags of salt while the light was showing Low before I realized I had a test strip issue. These new strips read right at 3700, which is more or less where I expected to be. So I think my Intellichlor may be reading Low when the water is actually okay. I had read something about calibrating a SWG, maybe that's the answer?

 

[grumpy]

My IC-40 shows low salt too. It varies between 2700 ppm and 2900 ppm frequently and for no reason that I can detect. The strips say that my salt is 3600 ppm and are very consistent.

I have my unit set on 10% with 12 hour per day run time and it easily maintains 4 to 5 ppm FC depending on bather load.

For now, I've decided not to calibrate the SWG. I suspect that it would begin to drift again and I'd spend a lot of time chasing it. After all, the yellow light on the cell is only telling you to check the salt. If it turns red, that's a different story.

Is your FC still 2.0 ppm? What is your SWG setting? How long is your pump run time? How are you testing your water? We'd like to see a full set of numbers from a complete test to help you keep your pool Trouble Free.