Pinpoint conductivity meter craziness!

[capted]

Does anybody have issues with the pinpoint conductivity meter like myself? I calibrated it with pinpoints own fluid, Randy's DIY standard for conductivity meters and accurasea standards. Reads dead on at 53ms after calibration with all 3 standards. Next I have 3 refractometers(all different brands) that I calibrated with both Randy's DIY and accurasea. They are all dead on also at 35ppt. Now here's the kicker, I checked my tank water with all 3 refractometers and my water is at 35ppt on all 3 but the pinpoint reads 52ms. I had the sample water in a beaker so that rules out electrical interference. Driving me nuts!! Oh, I also had the tank water and the standards at 77 degrees to rule out temp issues. Can't figure it out.

 

[Randy Holmes-Farley]

The difference might be a temperature effect or something else, but I'll note that between 52 mS/cm and 35 ppt is only 0.66 ppt, and all of these devices have expected accuracy that likely cannot readily distinguish 34.3 ppt from 35 ppt.

The Pinpoint does not give an error specifications, but the Hanna meter says it is accurate +/- 1 ppt.

Marine Salinity Tester - HI98319

Hanna Instruments HI98319 Marine Salinity Tester measures conductivity (EC) to determine the salinity of natural and artificial seawater within seconds.

www.hannainst.com

 

[capted]

Thank you professor Randy!! I have read your articles from way back and often go back to them when I have a brain fart... Good point about the error spec. I just don't understand how it reads 53mS in the standard but 52mS in my sample water while my refractometers read 35ppt in either solution. I'm a mechanic by trade and being off .05" would drive me crazy!!! I get that .66 ppt is no big deal though.

 

[capted]

@Randy Holmes-Farley. I read a post where you added up your major elements from your own ati test to figure out your salinity. I have my ati results and it showed my salinity as slightly high. Is there a specific # for each element or just a # for all of them added together? I can't remember the # for natural seawater when added together. Sodium + chloride+ the other ones added together that you stated.