Quote from Goldline Controls AquaRite FAQ http://www.goldlinecontrols.com/Supp....aspx#ar_faq12


Why doesn’t the salt reading match a tester?
The chlorinator, as well as any tester has a tolerance and when tested, commonly the unit will not read exactly the same as a tester. Most test units as well as the chlorinator have a tolerance of roughly 100-300PPM so seeing readings 400-600PPM off is common.
You may want to go through the Diagnostic Display and see what Amperage is being used. I think I read here that 8 Amps is the cutoff where you get High Salts/High Amps.

Further down in that FAQ there's a procedure for "recalibrating" the displayed reading, that may be of interest, especially if you need to "eliminate the error lights."