Automated refractometer?

[Formulator]

Conductivity probe salinity meters are unreliable in my experience and I’m wondering why we don’t have a better solution for automated salinity monitoring. I’m sure with a refractometer, dosing pump and a camera with some simple machine vision, it would be easy enough to make something, right?

Has anyone tried or am I missing some kind of major hurdles to automating this kind of testing?

 

[theatrus]

Conductivity probe salinity meters are unreliable in my experience and I’m wondering why we don’t have a better solution for automated salinity monitoring. I’m sure with a refractometer, dosing pump and a camera with some simple machine vision, it would be easy enough to make something, right?

Has anyone tried or am I missing some kind of major hurdles to automating this kind of testing?

It wouldn't even take machine vision or anything fancy. Digital refractometers just use a linear CCD.

The issue is going to be maintaining the clean surface of the sample prism.

 

[danreef55]

As far as answering your question I am useless but here is something to consider...
According to Conor a Coral Vue rep the Hydros salinity probe is accurate. Today just purchased a

Digital Seawater Refractometer MA887 w/Protective Case - Milwaukee from Saltwater Aquarium had them on sale. I will use the Milwaukee to take weekly for a month in an effort to determine how much saltwater is being removed by the skimmer and salt creep. Will add a dosing pump to replenish. After that I may get the Hydros to monitor salinity and cross check simply because I like technology:)​

 

[theatrus]

According to Conor a Coral Vue rep the Hydros salinity probe is accurate. Today just purchased a

Digital Seawater Refractometer MA887 w/Protective Case - Milwaukee from Saltwater Aquarium had them on sale. I will use the Milwaukee to take weekly for a month in an effort to determine how much saltwater is being removed by the skimmer and salt creep. Will add a dosing pump to replenish. After that I may get the Hydros to monitor salinity and cross check simply because I like technology:)​

And thats a prism with a linear CCD sensor and a known light source. The actual accuracy of those is not great but they're relatively repeatable. Make sure to flush the sensor glass well.

Salinity probes are accurate, for a time. They're subject to the same fouling concerns of the electrodes, and the high K probes used for saline measurements just end up with tiny electrodes and lots of salt still causes long term issues with the electrodes.

Platinum black electrodes are what you want in salinity, but they're pricey (though less than a prism). And still can be fouled dropping the conductivity measurement.