Salt PPM increasing

I have 15000 gallon pool with a Aqua Rite Salt Generator wich I replaced a circuit board in in May. When it was added the salt PPM reading on the panel was running at 3300. After a few weeks the salt PPM went up to 3500-3600 and stayed there unitl this weekend. When I checked it my salt PPM on the display was 4000 PPM. Since I have not added any salt to the water this year, what would cause the PPM on the panel to go up?

The only thing I did different this year from other years was put a chlorine tablet in my pool when the SWG went out to maintian chlorine in the 90 degree weather until I could get it repaired. Chlorine stabilized after system put back in operation.

I have not drained the pool at this point I just don't understand why the PPM has increased without salt?

Is your water level lower? I see the same thing on my aqua rite when the water level drops an inch or two. If water is lost through evaporation rather than splashout it will cause a slightly increased reading.

Might also be worth cleaning the cell; although I bet that's not the problem.

If you're sure there's not been a loss of water, and are still perplexed, I'd recommend getting some salt test strips to compare readings.

Water levels are normal and I will clean the cell to see if it makes a difference if not I guess I will need to check the salt