Trouble with salt readings - strips vs. SWG

[chazas]

I just opened my pool and am having trouble with the salt readings.

Test strips (a couple of years old) show the salt level at 3540, which is surprising since that's about where I thought I left it last year before closing.

The reading on the Aquapure SWG shows 2400.

The pool temperature is only about 64 degrees, but there is nothing in the Aquapure documentation that shows that would affect the salt calculation.

Which number should I believe? Could the higher reading be the result of old and faulty test strips?

 

[Strannik]

temperature does affect salt calculations as most of the SWG measure current vs voltage or in best case - conductivity

i would trust the salt strips more but i would get fresh ones

 

[JasonLion]

I have found that the salt test strips tend to go bad quickly after their expiration date. I would not trust strips that were past their expiration date.

 

[chazas]

Thanks. It was the test strips. They didn't expire until next month but were bad already.

New strips showed a reading of 2500, basically agreeing with SWG.

Now to get the salt - we use a maintenance guy to open and he owes us the 200-ish lbs of salt we need.

I am always shocked at the volume of salt needed when we have to adjust our 34,000 gallon pool. Just for grins I plugged it into the pool calculator and it would have required almost 1000 lbs on initial start up! I wasn't around when our pool builder did it but especially since he used Mineral Springs Beginnings that must have cost a pretty penny...

 

[chazas]

Resurrecting an old thread as I'm having the same problem with my just opened pool. The SWG reads low salt, 2300. Probably low due to the cold temperature, but still. The "new" test strips I bought last spring, with an expiration date of 2/2011 are reading 4000. Cannot possibly be right.

I will order new test strips but the expiration date on these things seems to have zilch to do with when they actually go bad.

 

[Bama Rambler]

This makes me wonder what the storage requirements are to get them to last till the expiration date??

 

[chazas]

Good question. They were stored over the winter in a heated space.

 

[Pool Clown]

Doesn't anyones local pool store check salinity with an accurate, non test strip device?

 

[Wild Duk]

Mine do. I believe they have a unit that measures conductivity....

 

[chazas]

What local pool store? (The closest one to me is at probably 10 miles away, in DC area traffic ...)

 

[bk406]

Doesn't anyones local pool store check salinity with an accurate, non test strip device?

Mine does. Almost always comes within 200-300 ppm of my IC-40 reading. The salt strips are usually off by close to 800-1000 ppm (higher reading, not lower)