(4) 40# bags of regular salt -- regardless of grade -- will raise the salinity level of a 10,000 gallon pool 160 x 12 or 1920 ppm (NaCl). I checked this against Zodiac's own manuals, just to make sure of 'apples-to-apples' measurement. (http://www.zodiacpoolsystems.com/Pro...uaPure-Ei.aspx -- your unit is discontinued).

How are you measuring your salt level? If it's from a readout on that unit, then there's a sensor or calibration problem.

BTW, *if* you have an accurate chlorine test (eg, Taylor K2006 or other DPD-FAS kit), you can turn on the SWCG, and collect samples from just in front of the pool return, and compare them to water collected from just in front of the skimmer (should NOT be the same place!). If the return water is significantly higher in chlorine than the outflow (skimmer) water . . . your SWCG is working to at least some degree.