Red sea refractometer

[Velcro]

I must be missing something. When I used 35 ppt calibration solution to calibrate this thing today, I noticed that 35 ppt corresponds to 1.025 on the SG scale, not 1.026. What gives?

 

[AdamNC]

If you read the instructions it states to use RO/DI water to calibrate it.

 

[Velcro]

If you read the instructions it states o use RO/DI water to calibrate it.

I read the instructions and I was pretty disappointed that that was in there. It's common knowledge that is the worst way to calibrate a refractometer or really any device as far as calibrating at a point that is nowhere near the typical usage range.

I actually initially calibrated it with RODI and when I checked that calibration vs 35 ppt reference solution it was 4 ppt off... Silly.

 

[AdamNC]

I dunno. Been using mine with ro for the past year or so with no visible ill effects. I've always read consistency is best even if it's slightly off.

 

[Velcro]

I dunno. Been using mine with ro for the past year or so with no visible ill effects. I've always read consistency is best even if it's slightly off.

That's true, I just work with measurements for a living so accuracy is a bit of an OCD thing for me.

 

[pugcrush]

I kind of hate mine. You have to calibrate it each time & I've heard this from a lot of people! So that might be something to keep in the back of your mind if it's off each time.

 

[Velcro]

I kind of hate mine. You have to calibrate it each time & I've heard this from a lot of people! So that might be something to keep in the back of your mind if it's off each time.

Since I've calibrated it to 35 ppt with the calibration solution, I've rechecked it 3 times and it has stayed dead on. From my experience using refractometers in homebrewing, it's important to have a religious routine for precision... use it in the same ambient temperature and under the same light.