Learn from my mistakes

[MitchK]

Thought my last few beers were finishing way too high gravity. Wasn't sure if it was mash temp, cold ferment, inadequate aeration of wort...

Just noticed my hydrometer floating in a flask of starsan solution. Replaced the starsan with water to check. 1.004. What the fuck.

Guess I'm getting a new hydrometer.

[Lucas]

Or just calibrate it! Use water and sugar in fixed amounts to see if it is just 4 points off everywhere. Then it is still easy to get a good reading.

BYO article about calibration

[sheppard107]

My hydrometer reads exactly the same; they must be twins separated at birth. One of these days I'll get around to doing a proper calibration, but for now I just assume it's reading 4 points to high everywhere on the scale. Good enough for me right now.

[mstead]

Did you account for temperature of the liquid? I believe hydrometers are generally calibrated in liquid at 15 or 20C.

Check online for a temperature adjustment calculator. The instructions that came with it will likely have a temp adj chart as well.

If it is still off, just do what the others recommend.

[MitchK]

Mine is supposedly for 68f which is what I was measuring at.

I'll have to look up how to do the sugar water thing to see if it's equally off across the scale. I also was loaned a refractometer to see if I like that setup better.

For some reason I just assumed since the hydrometer is lead shot and glass that they would be made precise enough to not be this far off.

[CorneliusAlphonse]

there are any number of reasons it could be off - eg, paper gradations slipped down a mm or two after adding shot, or a touch more glass got left at the top than normal when it was sealed. i only really use my hydrometer on a comparison basis - og to fg to calculate alcohol, and fg not changing to make sure ferm is done. otherwise, i judge a beer's sweetness by taste, not by bulk liquid density.