Super Accurate Auto Top Off

[Anonymous]

I have this idea for making an auto top off system that used the electrical resistivity of saltwater to sense changes in salinity. All I would have to do is correlate the 1.025 specific gravity with an Ohm measurement, then design a simple logic circuit to activate a pump when the resistivity decreases. Do you guys forsee any problems? Is there anything else in that tank that might change the values besides the salt concentration? This is assuming I don't dose any Calcium.

 

[Anonymous]

There are already salinity-based auto top of out there, IIRC. This is not as accurate as water-level-based approach, since salinity meter that is precise and accurate enough for topoff is not cheap to construct. It is also tends to be affected by biofouling and other sensor issue.