Refractometer calibration???

[thewire]

i have decided to buy a scale since i m expanding my drug business as well LOL....

Make my own solution.

 

[Reef.]

I have 3-different types of solutions right now and they all read different, Brightwell being the highest. I’m not completely sure which one is correct. When I raised my salt to match 34 according to Brightwell, it started doing better.

With my refractometer calibrated with Brightwell at 35ppt. Then the others show
AquaCraft at 32/33
BRS at 30

I have a digital scale, but doesn’t read down to .01, I think I’m going to buy one that does.

I would buy one, if you want you can make a bigger size solution so the .01g doesn’t become as important, but worth buying one if you can.

 

[wilsonline]

That's normal. The zero reading is wrong. As long as the 35ppt is good, you are good to go.

this.

 

[wilsonline]

The question does RODI supposed to read 0 ppt using the standard refractometer? or maybe the Brightwell is correct?

I don't know the Brightwell stuff, but I wouldn't rely on RoDi water as a calibration solution. Ideally, calibration should be to the same salinity you aim for, so something like 35 ppt solution.

 

[thewire]

I don't know the Brightwell stuff, but I wouldn't rely on RoDi water as a calibration solution. Ideally, calibration should be to the same salinity you aim for, so something like 35 ppt solution.

I ended up making my old solution.

 

[ryshark]

Buying a .01 gram scale and making my own solution, ended up being the best thing for me too.

 

[Randy Holmes-Farley Verified Community Expert]

The problem is that most refractometers sold to hobbyists are not true seawater refractometers, but rather industrial brine (NaCl) refractometers resold to hobbyists. The people selling them likely don't even know the difference. The issue is that the relationship between what is measured (refractive index) and what is reported by the device (salinity) is different for seawater and NaCl.

A brine refractometer cannot read both 0 ppt and 35 ppt seawater correctly. A perfectly made brine refractometer that is perfectly calibrated at 0 ppt will INCORRECTLY read 35 ppt seawater as 33.3 ppt.

For that reason, and others, and since you likely want to measure 35 ppt and not 0 ppt, it is best to calibrate at 35 ppt.

Refractometers And Salinity Measurement
http://www.reefedition.com/refractometers-salinity-measurement/

 

[Blakjax]

I ended up making my old solution.

And once you made your own solution what was the result? Did your refractometer still show something different than 0 when rodi was used?

 

[CK00020]

Buy a hydrometer