[thcipriani]

In addition to these tips there is one other point to consider. Mash efficiency is a number with two components:

• conversion efficiency
• lauter efficiency

kai has a really thorough article on his wiki: http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency

Most of the suggestions here have to do with conversion efficiency, but your problem may have something to do with how you are sparging/lautering. Or it could be a combination of the two.

Good luck in troubleshooting and let us know if the problem persists.

[GS]

I'm going with the "volumes off" theory.

I'm curious about one thing. Your strike volume was "about 20 quarts." Then you added 8 quarts of 180F water, then you added another 18 quarts of water, and you let it sit in the tun for 30 minutes before draining? That's 46 quarts, or 11.5 gallons in what I am assuming is a 10-gallon mash tun.

The thing that makes me think your volumes are off is the total amount of water you used. My recipe for a rye calls for 12.25 lbs of grain.

Strike: 4.5 gallons
Mash-out 1.9 gallons
Sparge: 3.3 gallons
Total: 9.7 gallons.
Boil volume: 8.25 gallons