It’s model IC15.Get the proper salt test - or - gasp - take a sample to a pool store and see what they get for a salt content (but still get a test kit for the future). If your IC?? is showing low salt and you have a proper salt content in the pool, you may have a bad flow switch. Somewhat common in the Pentair IC. If under warranty Pentair will replace. If not under warranty, then you can get aftermarket flow switches for around $60 and they are easy to replace.
Can you update what SWCG you have?
Thanks for the info.An IC15 is rated to generate 0.6 pounds of CL each 24 hour period if run continuously at 100% generation. That would put 3.6 ppm FC into your 20k gal pool each 24 hour period.
We here at TFP recommend using a SWCG that is rated for a minimum of 2X your pool volume. In NY, that will be sufficient. So the IC40 (Pentair rated for 40K gallons) meets that criteria.
Do you have automation? There are cheaper/better warranty SWCG's out there but if you have Pentair automation you will need to stay with a Pentair SWCG. You do need to have a timer for the SWCG (if you do not have automation) as you must never have power to the SWCG when the pump is off.