My pool's salinity is fine, 3300 ppm according to the pool store. When my salt cell is resting, the salinity sensor agrees with that reading. However, whenever my "cell on" light comes on, the salinity reading immediately jumps up to 5000 ppm, then reads "H.H" and the salt cell turns back off. After 10 seconds or so, the salinity reading comes back into range. When it drops below 4000 ppm, the salt cell turns on again, and the cycle repeats.
I have performed the front board test, and a couple of the numbers were off by one. I am told that is no big deal and that my front board is probably ok. I also did the voltage checks on the salt cell and the backboard, and all was well.
My next step, I think, is to replace the flow/salinity sensor. This is proving more difficult and expensive than I thought it would, because I have the old-style 2-port cell with the separate sensor. Most of the sensors I find online are designed to fit into the third port of the new-style cells, and I'm not sure if those will work with my system. The price difference between those and the few old-style sensors is significant, though...
Am I doing the right thing here? And do I have to go with the more expensive sensor? Are they interchangeable?