Is there a way to connect a salinity/conductivity probe?

[kdx7214@gmail.com]

Right now I monitor pH and several temperatures for the tank.  I'd love to be able to monitor salinity as well.  I saw on Reef2Reef that there are really pricey conductivity probe/sensors that can be used, but is there anything reliable that is more affordable?  I'm not sure I want to spend $200+ to avoid using a refractometer every time I do water testing.

[Rob F]

The Atlas circuit you saw is what most people use but yes very expensive. If you can find a circuit that connects to the Pi and has some sample code to get it working you can use that and edit the code to save the salinity value to a text file which you can then read and import values into reef-pi for monitoring and control. I think I'll have one to offer in maybe 3-4 months that'll be $40 + probe.