As I readied my pool for the season, I added the proper amount of salt to reach 3600 PPM. Let me start by saying my IC40 was manufactured in 1/18. With all lights green, I noticed that the low salt light on my IC40 never turned green and was red and was never producing chlorine in the pool. I looked at the control panel and it was reading 0 PPM. It has never read zero, so the first thing I did was acid wash the cell. I then tried to reset by disconnecting. I have held the "more" button down and even spoke to Pentair. Their suggestion was a new flow switch. Today I have installed a new flow switch and the light is still red....maybe it takes a while for it to read with the new switch or does anyone have any other suggestion to remedy this problem. Many thanks in advance!