Hydrometer questions

[jitsyeti]

I'm on my 5th batch of beer. This one I switched to BIAB from extract kits. Couple of questions about the hydrometer...

1. I've read they're calibrated. At the bottom of mine it says Sp.Gr. 60/60 F. I'm assuming that means it's calibrated at 60 degrees?

2. How often should I take readings? I was just doing it before the fermentor and before I put it in the keg. This last batch I took a reading before the boil, but it seemed off. (Could be the weird way I ended up doing the brew in a bag)

3. Is a refractometer better, more accurate or easier?

Thanks!

 

[max384]

Yeah, they're calibrated at 60 F.

Take readings as often as you'd like, depending upon what you like to keep track of. I take two readings. One before the boil so that I can determine my mash efficiency, and one before pitching yeast so that I can determine both my brewhouse efficiency and OG.

A refractometer is more convenient. You don't need to cool down the wort and you only need a drop or two. I use my refractometer for all of my prefermentation readings, and a hydrometer after fermentation.

 

[slym2none]

Refractometers are mostly for pre-fermentation readings. Alcohol throws off the equations, and while there are calculators for such things, to me they seem to still be a big guess as to how close the readings really are.

Use a refractometer before fermentation & a hydrometer after fermentation, is my advice.

 

[dsniegocki]

1. Yes, temperature of the liquid does affect the reading. It should be calibrated at 60F, and for water that would read a 1.000; if you are curious, check water at 60F, and then at a couple of different temperatures like 72F, 55F etc to get a feel for how much it drifts.

2. once just before fermentation and then once before kegging will be the bare minimum to give you an idea of how much alcohol is in solution; there are charts (and formulas) around the web to calculate this from these two readings. Some folks (like myself) also measure during fermentation to get an idea of how it is progressing. Taking a reading before the boil is also important, as you may want to adjust the wort prior to the boil to hit a target OG... it will seem "off" from what your target OG is because moisture is lost during the boil, but fermentables are not... so a 1.035 pre-boil might end up as a 1.050 post-boil, since pre-boil the fermentables would have been in 6.7 gallons of liquid, whereas post-boil the same fermentables are now in, say, 5.2 gallons.

3. Tricky question. Refractometer is easier, absolutely... wastes much less beer/wort and quick to get a read too. However, once fermentation begins, the readings will drift off and you will not be able to use the refractometer without adjusting the measurements. There are tools available (such as in beersmith) that make the calculation for you based on your OG. The hydrometer does not suffer from this.