ATI ICP - Salinity Issues

[ceaver]

Scroll down to the section on Refractometer standard. Underneath table 2 is the recipe for mixing up some solution
http://reefkeeping.com/issues/2004-06/rhf/index.htm

Sweet, thanks for pointing me to this resource!

 

[ceaver]

Well I'll be d@mned. So I made up the DIY calibration solution to @Randy Holmes-Farley's specs, using a digital scale that measures tenths of a gram, and Morton's kosher salt, which they state can be subbed at the same volume with table salt.

My BRS refractometer calibrated to 35 ppt using BRS juice is reading about 38.5 ppt with the calibration standard I just wipped up, which equates to about 1.029 sg. This seems to be about the same difference my ICP reported, about 3.5 ppt (they showed me at about ~31.5). So apparently my tank has been running at about 1.022 sg for some time now. Lovely.

Is it reasonable to conclude that the refractometer is okay, but my BRS calibration juice is bunk?

 

[ceaver]

And I also just confirmed it at the LFS. They actually used a plastic swing arm hydrometer to measure and it showed between 1.021 and 1.022 sg. Apparently the BRS calibration juice is junk!

 

[minus9]

And I also just confirmed it at the LFS. They actually used a plastic swing arm hydrometer to measure and it showed between 1.021 and 1.022 sg. Apparently the BRS calibration juice is junk!

Like I mentioned, you should never have to shake calibration solution before use.

 

[Randy Holmes-Farley]

Well I'll be d@mned. So I made up the DIY calibration solution to @Randy Holmes-Farley's specs, using a digital scale that measures tenths of a gram, and Morton's kosher salt, which they state can be subbed at the same volume with table salt.

My BRS refractometer calibrated to 35 ppt using BRS juice is reading about 38.5 ppt with the calibration standard I just wipped up, which equates to about 1.029 sg. This seems to be about the same difference my ICP reported, about 3.5 ppt (they showed me at about ~31.5). So apparently my tank has been running at about 1.022 sg for some time now. Lovely.

Is it reasonable to conclude that the refractometer is okay, but my BRS calibration juice is bunk?

It may be that the BRS fluid is off for some reason, yes.