After several weeks my probe settled in and has been pretty consistent. Over the last 24 hours it has varied from 61.2 to be 61.8, and if you overlay the temperature graph on top of the salinity graph, they match up almost perfectly. Of course what I learned a while ago is that I really don't need to follow the salinity, so I just have it as a failsafe to catch a catastrophic problem with my ATOI am fine with my salinity probe for what it costs. There is no way to measure sodium chloride molecules in water aside from a mass spectrometer. The apex salinity probe is therefore measuring conductivity. There are lots of things you can put in water to make it more conductive, salt just happens to be what is in our aquariums. So it’s never going to be flawless, but my experience with the apex probe is pretty good. I agree calibration is tough, but it can be done. Air bubbles: every probe is susceptible to this. Yes even temperature if the bubbles accumulate right. There are a lot of people that have complained about this in this thread, but I don’t see it as that big of an issue. I really think most people would be happy if calibration was done properly (as stated i don’t use apex cal fluid) and measures are taken to avoid noise in the lines. I don’t let any of my probe lines run by power lines.
just my two cents.