Small grind effects on O.G.

[KyBeer]

I just changed up my milling and mashing at the suggestion on a blog from person who knows more than me.
I milled down to .030 and used a BIAB to line my 10 gallon mash tun. Because I had a fear of a stuck mash I threw in a couple cups of rice hulls.
This is the fourth of fifth time I've brewed this beer and was expecting a O.G. of 1.048. I got 1.058!
I use continous sparge and my wort volume was only slightly higher than expected in the BK.
My question is: Could .040 milling reduced to .030 make that much difference?

My efficiency numbers are all mess up if this is true.

 

[SonomaBrewer]

Nice!

What is your mash efficiency at 1058 vs 1048?

Depends on mash thickness and sparge among other variables, but reducing crush size with BIAB could feasibly improve mash efficiency by 10-15%.

 

[KyBeer]

My efficiency jumped a bit with the batch size and how I mashed. With a pale ale I could see 85%, but on some porters only 65%. I have varied my thickness from 1.25 to 1.75 qts per pound depending on the time I had to brew for the day. If I planned a double brew day a thinner batch makes the sparge shorter but a lower O.G.
Mash was 152 degrees.
I like the clean up with the bag, but I guess I will need to lower my grain bill or drink a bit less!

 

[IslandLizard]

I use continous sparge

Fly sparging? With the bag? Why and how?
What kind of mash tun do you use, a round cooler?

Could .040 milling reduced to .030 make that much difference?

Yes it can and it does! When we mill that fine we usually batch sparge, 2x is preferred.
Milling at .040" is quite coarse, but may prevent a stuck mash during fly sparging.
At 0.030" you'll get quicker hydration and possibly faster conversion, but may be too fine for good permeability during fly sparging. Your rice hulls will surely help keeping the mash lush.

Don't forget, any small kernel grain such as wheat or rye benefits much from finer milling. For example I mill wheat and rye at 0.025", barley at 0.035". That's without using a bag, and batch sparge twice. Mash efficiency 82-85%.

 

[KyBeer]

Yes, the round 10-gallon big orange cooler with a false bottom. The bag was suggested by someone to speed up clean up and is works great. During the sparge I recirculate the wort through a HERMS coil in the HLT. First sparge takes about 55 minutes. The second 45 minutes with a lower PH water at about 165-170 water from the HLT. After second sparge and I have gotten all the wort that would normally drain through the false bottom, I raise the bag and let it drain. I am getting almost 2 quarts on a big grain bill.

The big change to my mash process has been the finer milling. Now that I see the difference, I am wondering how small can I go? The added rice hulls and bag should keep the husk out of the wort. I think the husk in the BK might make a bitter taste that is not desirable.

I am planning to brew an imperial IPA soon and maybe I will mill at .025. I just can’t get over the difference milling has made in the conversion. Higher numbers and faster!

Thanks for the feedback.