DIY Automated salt water mixing system

[sphelps]

Originally Posted by kien

Somewhat related to this discussion, Steve, have you ever noticed your conductivity probe randomly read an incorrect value? I have thought about doing something similar in the past but I have found my salinity probe to be quite unreliable. Maybe I just have a bad probe? My probe (for my Profilux) can read the conductivity fine, but every once in a while it will ready a very inaccurate value. When I notice this I sometimes shaking the probe which helps. Sometimes it corrects itself. I've tried putting my probe in low, medium and high flow area but it still does this from time to time. For example, my probe has been reading 1.021 for the past couple of days but I know for a fact that it is 1.026. Anyway, I really don't trust my conductivity probe at all.

Mine seems pretty stable as every time I check it matches my refractometer but I measure salinity rather than specific gravity as I recall issues in the past relating to programming the controller to display readings in SG, something about a gravity offset calculation or something, can't remember. Anyway you should try recording the actual conductivity over time and see if that is changing before ruling anything out.