I an autopilot DIG 220/SC36 which keeps saying low salt, 1900ppm reading, add 112lbs of salt. I had added 80lbs a couple of days back and nothing. I added another 40lbs today and initially it read 4400ppm, then 2800ppm and it was running without the error or light blink. Half hour later back to the same error. My reading yesterday was 21v 5.6amps and this afternoon I replaced the entire manifold with tri sensor as recommended by tech support. I had a spare one that came with new cell. I also added the 40lbs after I replaced the manifold. My reading now is 1900 or 2000ppm and 17v 5.2amps. I have the dig 220 since 2003 and replaced the cell less than 2yrs ago. Any help would be greatly appreciated. I find these forums very helpful for not getting ripped off.