First AG - Low efficiency

60% mash efficiency or brew house efficiency?

If mash efficiency, then the first thing to examine would probably be the quality of your crush.

 

Your low efficiency was due to the top off addition. A half-gallon addition to 3.75 volume is 15% (dilution factor). Your 60% efficiency adjusted for 15% dilution equals 70.5%, about what you expect for batch sparging. Your options to keep efficiency up is to delete the top off . . . accept a lower volume. If you want more volume then add grain and sparge more.

 

Not sure I'm following you, but mash efficiency does not change with volume (due to boiling off or topping off). Gravity does, but efficiency does not. IOW, in OP's case, boiling off more water than expected, and then topping off with more water doesn't change efficiency.

Now, it's possible that OP measured gravity at a volume other than expected, and didn't adjust the efficiency calc for the difference in volume.

OP: What was your grain bill, OG, and the volume of wort when you measured the OG?

 

This is a good read:

http://braukaiser.com/wiki/index.ph...ity_and_efficiency_in_single_infusion_mashing

Summary:

Lots of factors contribute to efficiency, proper mash ph, and proper crush are two big ones.

 

If you had 6.75g preboil and ended up with 5 gallons post boil after adding 0.5 gallon x 2, then you boiled off 2.75g between the 2 boils in 80 minutes. That works out to 1.375 gallons per 80 minutes per boil, or 1.03 gallons per hour per boil which is fairly standard.

While the percentage can be reverse engineered from your post boil volume and post boil gravity (by factoring in your boil off rate), mash efficiency is generally based off of your preboil volume and preboil gravity.

Try to get into the habit of measuring your preboil gravity as it will make it easier for you to calculate your true mash extraction in the future.

 

If I read all of your info right, you used 10lbs of grain, and ended up with 5 gallons of wort @ 1.048. Now, the type of grain matters, but assuming an average of about 36 PPG fo your grains, your mash efficiency was about 67%.

 

You can also use post-boil volume and gravity, as long as you're willing ignore the small volume typically added by the hops, or adjust the final volume downward to account for them. But with most recipes, the difference is negligible.

 

Thanks for the correction . . . also good read from JohnSnow's link . . .

 

Very true and thanks for the correction. You actually caught me with my pants around my ankles before I had time to pick them up by editing my post / adding elaboration. I was trying to focus on the easiest way to measure it moving forward for the OP, which I believe is to generate mash extraction based off of a preboil volume measurement and preboil gravity reading. But I guess you could go by your post boil gravity and post boil volume just as easily, provided you know not to get confused and go with your volume in the fermenter since factoring those the transfer losses in would skew your extraction efficiency into a brew house efficiency measurement.

 

Generally your OG = post boil. Your preboil gravity will always be lower than your post boil gravity, since you are evaporating water during the boiling process which increases the sugar concentration of your wort. What brew app are you using? I use beersmith and it makes preboil gravity predictions, post boil gravity predictions, and post fermentation final gravity predictions.

 

What app are you using?

OG usually means gravity post-boil.

Preboil and OG are not the same.

 

It would not be the same. It's related by this formula...

(PreBoilOG - 1) * (PreBoilVolume) = (PostBoilOG - 1) * (PostBoilVolume)