Lower Effiency when mashing for high OG?

[BeantownR6]

when i brew for beers up to 1.070 seems i can get 65-70 percent effiency, i was mashing in a 10 gallon cooler, 5.2 PH stabilizer. ive since then switched to a keggle for mashing and recirculate and heat with and get the same efficiency.

the last 2 high gravity beers i did, one in the 10 gal cooler and one in the 13.2gal keggle with recirc and heat i was shooting for 1.090 and got gravities in the 1.070 range. i set up my recipes for 68%.

is it common when mashing large amounts of grain to get less efficiency? i mash with 1.25-1.5 qts/lb also.

i also batch sparge with both setups.

i think i need to crush my own grains.

thanks

 

[Hammy71]

It's been discussed on here before and I can't remember the logic. But yes....I usually aim my recipe for a few points lower when doing 10 gallon batches.

 

[knightbeer39]

Part of it is you tend to have a higher water to grain ratio to promote recirculating, but that doesn't explain your cooler mash tun efficiency. Part of it for me is that I do a bit coarser of a grind in order to insure I don't get a stuck mash when recirculating. For me also, the mash out has made a difference. In my old system I didn't mash out and really it was still converting right on through the sparge. Now with a mash out, I stop that conversion in its tracks. Fly sparging can increase your efficiency a bit also.

You will probably just have to play with your grind (you really should grind yourself if you can to fine tune) a bit, play with your water ratio and you may find you might have to up your grain bill a tad to get right where you want.