The Salt Reading Is “Off.” Can I Calibrate The System?

A Few Realities About Salinity Testing

When your SCG measures salinity, it is inferring the salinity from a measure of the water's conductivity. The number it figures, will be good enough but won’t necessarily match another form of measurement.

• Handheld electronic testers work on the same principle and measure conductivity rather than “counting” salt ions. Even when properly calibrated, an SCG and a handheld tester may differ by +/- 200-400 ppm.
• Aged test strips or reagents can throw off results. Generally, factors such as heat, light, humidity, and exposure to air can degrade the accuracy of these methods.
• Pool stores essentially use the same or similar methods with comparable accuracy.
• The uncertainty levels between one source and another can be additive, so if my testing is +/-150 ppm and yours is +/- 200 ppm, we have the potential to be off by +/- 350 ppm.

Is The Salt Reading “Off”

There are several principal causes for bad salinity readings including a dirty cell (and salt sensor), an incorrect cell type setting, or air in the cell.

• Deposits on the cell blades or particularly on the sensor need a thorough cell cleaning.
• Check the Cell Type or Cell Version. This is a brand/model specific issue, but for systems that have provisions for designating (usually) the cell capacity, an incorrect setting will give incorrect salinity readings.
• Air collecting in the salt cell can give you bad readings. If you have a transparent cell housing, look for an air pocket inside the cell.

But, Can I Calibrate The System?

Yes, some SCGs allow you to adjust the salinity reading which turns the question for those individuals into, “should I calibrate the system?”

Having pointed out the margin of uncertainty associated with any salinity reading, reserve calibration for offsetting a reading that triggers a high or low salt warning with the confirmed salinity safely within the recommended operating range. Small, apparent discrepancies should be accepted when they don’t pose a threat of tripping a high/low salt light.

Does My SCG Allow Calibration?

Amongst the SCGs that provide for adjusting the salinity reading are the Pentair IntelliChlor, Hayward AquaRite, CircuPool Universal, and the Jandy AquaPure. Click here for manuals and support information for these SCGs and to confirm with the specific manufacturer whether your SCG has this functionality.