Another Refractometer Question for Your Collection

So, I've been having problems with beersmith and my cheap-o ebay refractometer. When I do a distilled water test, it reads as 2brix. I can adjust that up to a higher number, but I can't adjust it down. The screw just won't go any tighter. The lowest I can get it to read is 2.

In beersmith, it gives an option to calibrate the refractometer. I typed in '2' in the blank where it says 'distilled water reading' and assumed that it was doing the correction for me. Out of curiosity, I recently changed that 2 to some other numbers to see what would happen and it didn't change anything when converting my specific gravity.

What do I do? Can I just subtract 2 from my brix readings and assume that is accurate?

I don't have a hydrometer to compare it's readings.

Most likely yes. You will have to subtract 2 from your readings.

I use a refractometer and a hydrometer. I love the refractometer best.