T Cell 15 bad?

[BigTallGuy]

If you go to the hardware store, you can probably find a 40 Lb. bag of Morton Pool Salt. On the back of the bag, it will tell you that the 40 Lb bag will raise the the PPM of salt by 480 PPM in 10,000 gallons of water. I would add 40lbs, Give the salt a day or so to dissolve, and check your reading. I would add smaller amounts from a second bag if needed, say half at a time. Bring it up slowly. If you over fill with salt you'll be draining and refilling.

[mas985]

Sounds like they are doing a TDS test which can have a lot of error as well unless the probe is calibrated often. Personally, I wouldn't trust a pool store test of any kind.