Efficiency calc questions..

I'm brewing up a 5g batch of BM's Centennial Blonde and I've got some questions about figuring my efficiency.

Mash in was 3g even, now I'm doing kind of a "fly-brid" sparge where-as I started a fly sparge, until I had 5.5g in the kettle, then just let the rest of the sparge water go and sit with the grains while I got the kettle on the heat, now I"m getting 2nds in a bucket.. Don't have a large enough kettle yet for a 8 gallon boil..

Question is, do I need to take samples of what's in the kettle, and what's not yet, to get accurate efficiency readings? Or just take a sample when the boil is finished..???

I believe you would need both runnings combined together pre-boil in order to get an accurate gravity reading so you can calculate efficiency although I'm sure there might be a way to calculate it separately as long as you know the volumes and gravity of each sample. I'm sure others will chime in to give you a better answer.....I only did my 4th AG yesterday!

The reason for taking readings mid brew is so that you can adjust the recipe as needed based on your efficiency. That way if your real picky you can alter hop additions or add some DME to compensate. If your just curious as to how your doing and don't plan on altering your recipe mid stream, then the gravity reading at the end of the whole process can also give you an efficiency that is just as valid.

Ok, that what I'm goin with then.. Thanks..

Flic said:

I believe you would need both runnings combined together pre-boil in order to get an accurate gravity reading so you can calculate efficiency although I'm sure there might be a way to calculate it separately as long as you know the volumes and gravity of each sample. I'm sure others will chime in to give you a better answer.....I only did my 4th AG yesterday!

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There is a way to calculate if, like Flik said, you know your volume in each container.

What you are basically doing is counting up your total gravity points and then dividing by your final volume to get the starting gravity for your beer.

It is pretty easy to do. If your primary kettle has a total of 4 gallons of wort in it you take the gravity and multiple by 4. Ex Reading is 1.030 at 155 degrees. You adjust for temp by adding .020 and then take the .050, get rid of the .0 and multiple the 50 by 4 (4 gals) = 200 Gravity Points. Next you take the runnings from the tun and do the same. Ex. 4 Gals at 1.025 (adjusted for temp) = 100 GP. = grand total of 300 Gravity Points.

If your final volume is 5 Gallons then 300/5 = total OG of 1.060. Compare to target based on recipe and adjust with DME or LME if you need to. DME and LME add 45 and 38 GP per pound respectively.

Depends on what is more important to you. Hitting your efficiency or your volume. I personally go for gravity every time. So preboil sg is what I aim for. If my volume is off I know I need to check my mill or grain...