Gravity Readings - Home Brew Forums

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09-27-2006, 05:39 PM   #1
Willie3

Recipes

Jun 2006
Hackettstown, New Jersey
Posts: 765
Liked 8 Times on 4 Posts

I got the gist of efficiency down but I am still confused on gravity.

First Question:

I read that when sparging you want to wait until your gravity reading is 10 points to be sure you have rinsed all the sugars. Where is this reading coming from (run off from the M/LT? If it is the run off do you stop it - take a reading - continue if necessary?

Second Question:

All malts contain certain Gravity Points (e.g. Pale Malt = 37 (points / # /gal) @ 100% efficiency)

In order to understand total Gravity Points available you have to calculate each type of malt in grain bill - e.g.

8.5 # Pale Malt (2R) = 8.5*37 = 314.5 total available gravity points (tagps)
1# Munich (US) =1*33= 33.0 (tagps)
.5# Carapils (US) = .5*33= 16.5 (tagps)
.5 # Wheat (US) = .5*39 = 19.5 (tagps)

Grain Bill Points = 383.5 (tagps)

Say that the wort volume is recorded as 5.5 gallons then the total expected gravity @ 100% efficiency is 1.070 or 70 gravity points.

Now in order to find out what the efficiency rating is at 100% extraction you need to divide by Wort Volume. In most cases I will be aiming for 5.5 gallons to ferment. However the Boil volume will be about 6.5 to 7 gallons. The question is which measurement do I use?

Then in order to find out what efficiency was achieved you divide the gravity reading into the total expected gravity at 100% efficiency. For example:

My gravity reading is 1.050. So I divide 50 into 70 and come up with 71.4% Efficient. This would be ideal for beginners. However I am confused on those two questions.

Can anyone clarify this for me?

Thanks

- WW

09-27-2006, 07:15 PM   #2
david_42

Recipes

Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
Liked 158 Times on 148 Posts

You can just take a sample from the runnings, you don't have to stop it. Adjust for temperture.

Quote:
I always use the gravity and volume going into the fermenter.
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09-28-2006, 07:08 PM   #3
Willie3

Recipes

Jun 2006
Hackettstown, New Jersey
Posts: 765
Liked 8 Times on 4 Posts

Thanks David that helps out!

- WW