Drop in efficiency

[floydmeddler]

I've been enjoying efficiency levels of 83% with my current 25kg sack of MO. However, last night and last week, my two brews came in at 72%. I mashed both times at a steady 65c-66c for 90 mins and did everything exactly the same as I normally do. However...

. The bag is nearing to an end
. The bag has been in a room of around 23c for the last few months... I know it should be much cooler!

Could any of these / both be the culprit?

Cheers

[6470zzy]

I would be more ready to blame your sparge technique than anything else. In a home-brew situation it is hard to get a really consistent sparge. Perhaps the quality of the grain at the end of the bag could also be playing into the game too, after all at the end of the bag you do ave a lesser quality grain to work with and a lot of dust/flour to contend with.

Cheers

[floydmeddler]

My sparge technique hasn't changed so I'm ruling that out. It's got to be the grain.

[trucker5774]

The same happened to me............all my method was the same but on my 2nd to last brew (which left 2KG in the sack) the efficiency dropped from 80/83% down to 70%. I have now started a new sack (same supplier) and the efficiency is up to 75% using a mix of the last 2KG from the old sack and 2KG from the new sack...............seems to be a pattern there!!!

[Horden Hillbilly]

My sparge technique hasn't changed so I'm ruling that out. It's got to be the grain.

That would be my guess too. I can recall that late 2007/early2008 quite a few forum members, including myself, noted a fair drop in our effiencies. Coincedence or the grain?

[delboy]

Was the sack of grain precurushed?

[rick_huggins]

Could your water properties have changed effecting the PH?

[trucker5774]

Yes mine was crushed........................mmmmm not sure a crushed sack is desirable