I am trying to use conductivity to measure a change caused by a salt tracer at different points along a pipe. My biggest hurdle is response time. Any electronics causes an unknown lag time between them which isn't really acceptable. My idea is to buy just the probe, supply it with a voltage on one side, on the other side put a resistor (of suitable resistance)and then earth it. I will then measure the voltage drop across the resistor by a data logger. I don't care what the conductivity is I just need to know when the tracer reaches the probes. Will this idea work? Are there any better suggestions?

Regards
Craig

 

I did a similar test with just plain salt (NaCl) and a DMM. I found there was almost no measureable change in conductivity for large
changes in salt concentration. You may have a problem with scale and resolution. I didn't take my experiment too far.