Partial mash and efficiency.

**FuelshopMcgee** · 07-27-2009, 04:35 AM

I know the way to check your efficiency is via hydrometer reading but how do you know what your efficiency is with a partial mash? I'm just curious as how to figure out what my target gravity after my mash is supposed to be because of my malt extract not being added yet I'm not going to be near my SG that is in beer tools.

JMSetzler · 07-27-2009, 04:47 AM

I don't know about Beer tools, but you can treat your mash like a separate beer. You would calculate the efficiency of the mash the same way you would in an all-grain beer. You would just calculate the potential of the mash and compare it with what you actually get to find that efficiency.

**FuelshopMcgee** · 07-27-2009, 02:06 PM

duh...now I feel dumb thanks for the help!

**Bobby_M** · 07-27-2009, 02:34 PM

BTP knows that malt extract additions are always worth 100% efficiency so the number it gives you is only based on malts that are mashed. However, if you wanted to know what your mash efficiency was prior to adding all the extract, measure the gravity and temporarily reduce your batch size down to the actual volume you got out of the mash and enter the gravity into the analysis tab in "OG".

**FuelshopMcgee** · 07-28-2009, 11:50 PM

well if the calculations are correct I hit damn near 80% today!?!! Feels good!

SavageSteve · 07-28-2009, 11:58 PM

I use BTP, but I find this website much easier to use for determining efficiency:

Brewhouse Efficiency Calculator | Brewer's Friend

-Steve

**Bobby_M** · 07-29-2009, 03:35 PM

I have to ask. You already have your grain bill in BTP so why wouldn't you just look at the "efficiency" field to know your efficiency?

**FuelshopMcgee** · 07-30-2009, 11:32 AM

Thats what I did...I started out using 70% and it did not match the hydrometer readings I was getting so I kept bumping it up until it matched.

SavageSteve · 07-30-2009, 04:19 PM

Quote:

Originally Posted by Bobby_M

I have to ask. You already have your grain bill in BTP so why wouldn't you just look at the "efficiency" field to know your efficiency?

As far as I understand, the efficiency field is to indicate the expected efficiency when formulating the recipe. I haven't seen where it will calculate the actual efficiency of a partial mash based on SG and volume data. Maybe I'm missing the boat on this?

-Steve

**Bobby_M** · 07-30-2009, 04:44 PM

You can do as suggest above... keep modifying the efficiency number until the OG matches what you measured, but you can also just click on the ANALYSIS tab and enter your measured OG.

Now, getting a bit more specific...
If you're measuring preboil gravity, make sure the preboil "kettle" volume that the software says you should have is actually what you DO have. Then hold the mouse over that field (kettle volume) and it will pop up a window that shows you what the preboil gravity should be (if you're on track for your expected efficiency that is). If it doesn't match, adjust the efficiency until it does.

If you're done with the boil and want to measure brewhouse efficiency, make sure your fermenter volume accurately matches the finished batch size in the software (adjust if necessary), then go to the analysis tab and over-write your OG. Now it will tell you your brewhouse efficiency.