second guessing my refractometer

[oliver]

You didn't mention chilling the hydrometer sample or the refractometer sample. And I hate to bring this up but the scale you're using is not the issue. If the refractometer is of any quality whatever, the SG and Brix scales have been calibrated with each other. 16.6 Brix equates to 1.068 SG. In the picture above, the Brix is 23.3, the SG 1.091. That's wrong according to the Brix table I reference: It should be 1.098. The problem isn't whether to use Brix of SG, it's a faulty scale in the refractometer.

I've stopped measuring with the hydrometer on brew day because, when I cool the refractometer sample, I generally wind up with 1 to 2 degrees of SG between the two. That's within reading error on my hydrometer so I just go with what the refractometer says. Even the three degree error you mentioned is not that significant in homebrewing. Your call, though. I like the convenience and smaller sample size.

no I get it. the tests I did proved that my refractometer works, but only the brix side of it is trustworthy.

 

[Nosybear]

Agreed. I understood the point you were making is that measuring in Brix was somehow superior to SG as a general case, not just for your specific refractometer. Either are equally useful (the point of my graph). Use the scale that works best for you.

I believe most pros use Plato, roughly equivalent to Brix, but don't quote me on that without looking it up.