High OG brew w/ low OG hydrometer

[eggraid101]

So I'm brewing an Imperial Stout type beer, but my hydrometer only goes up to 1.070. I'm expecting it to be higher than that. If I dilute the wort with the same volume of water, and the hydrometer reads 1.040, is that equivalent to a OG of 1.080? If not, how do can I figure out what my OG is? Thanks!

BTW, the imperial stout is a partial mash, and this 5 gal batch has grains weighing in at about 8 pounds! I'm psyched. Hopefully I got my water chem calculation right, because I'm adding over 10 g of Calcium Carbonate. :rockin:

 

[suprchunk]

I don't know the formula for dilution. But an extra 5 bucks for a hydrometer would be well worth the investment. Or 30 bucks for a refractometer is money more than well spent.

 

[eggraid101]

I hear you! But it's too late now for this brew. Anyone?

 

[McGarnigle]

I would bet you would just double it. 50% H2O @ 1.000 + 50% wort @1.080 = 1.040.

 

[strat_thru_marshall]

I would bet you would just double it. 50% H2O @ 1.000 + 50% wort @1.080 = 1.040.

You cant argue with the laws of math

 

[eggraid101]

Oooh, I have a beer in the fermenter that is steady at 1.010, I'll do an experiment with that. I'll get back to you all this afternoon I hope.

 

[eggraid101]

Well, the experiment didn't go very well. I used equal amounts of water and beer with the 1.010 brew, and it came out less than 1.005, or it may have been user error.

When I tried it with the high OG wort, it came in at 1.040, which may have been just about right, but I think the water I used in the hydrometer was a little too warm. It's not too big a concern, just interesting to know. The Stout is bubbling away as we speak.

 

[shortyjacobs]

It should work just as you said. Mix 50/50 wort and water and you should get 50% the reading.

With BEER, it's different. Wort is sugar and water. Beer is sugar, water, and ALCOHOL. The addition of alcohol to the mix, (alcohol, which has a SG of 0.79), adds a third variable that you are also diluting.

So, this trick works with wort, not with beer. For you, you should be able to dilute high SG wort 50/50, measure the SG, and double it to get the true OG.

 

[eggraid101]

That makes perfect sense, Shorty. That's why the hydro reading post fermentation was off from the 50% I thought it would be.

 

[david_42]

Shorty's point is also why we talk about apparent attenuation, not actual and using a refractometer for finished beer is tricky.