Floating Hydrometer incorrectly calibrated?

[ctdenney]

I have been using a refractometer for a while now, but decided to double check it against my floating hydrometer on my most recent brew.

When I checked my OG, the refractometer said 1.051 (target was 1.044, but I boiled off a bit too much water) and the hydrometer said 1.061! I assumed the refractometer was off and adjusted it to match the hydrometer but then had the excellent idea to check them both against water (before you ask, all samples were within 5 degrees of 60F), now both of them were reading 1.010 instead of 1.000. I re-calibrated the refractometer to read 1.000 but obviously can't do anything about the hydrometer. While it wasn't DI water, I am assuming that the difference between DI water and tap wouldn't be that large.

Did I get a bum hydrometer? Can I use it as is and just subtract 1 gravity point off all the readings?

 

[Naturallight16oz]

Tap it in your hand to make the paper inside slide in the direction that you need it to go.
If that makes sense.

 

[Cyclman]

Not all tools are precision made (or durable over time), one reason an adjustable refractometer is a great tool.

 

[robfar]

Place your hydrometer in 60F distilled water. It should read 1.000. I have two that don't. If the paper scale is just out of position, then adding or subtract the error will work. If the scale wrong, then you would have to really calibrate it with a known sugar solution.

 

[zachattack]

I just have a "SUBTRACT 3" note written on the storage tube for my hydrometer. I've had 3 hydrometers and 2 of them have been off by about 3 points.

 

[Naturallight16oz]

The paper inside of mine is not glued in place, so if it is bumped a little too hard the paper can slide and throw it off. so i gently tap it in my hand to make the paper slide back. Then i check it in water. then repeat till it is correct.

 

[ctdenney]

The paper inside of mine is not glued in place, so if it is bumped a little too hard the paper can slide and throw it off. so i gently tap it in my hand to make the paper slide back. Then i check it in water. then repeat till it is correct.

I tried tapping and it didn't budge. Guess I'll just remember to subtract.

Thanks for the feedback everyone!

 

[WoodlandBrew]

+1 to the tapping trick. Mine moves, but very slowly. Maybe 10-20 times of dropping it 1/4" on a countertop to move one point.