Help tracking an efficiency problem

[zoomzilla]

I've been brewing a lot with vienna and munich malts, which I've read can have trouble with full conversion on their own. I've asked on this forum and many people have said they have no problems brewing entirely with these malts. My efficiency is always right about 75% but recently it's fallen to 55% when using these base malts. Here are the numbers from today's brew:

5.5 gallon fermentor volume.
6lbs Vienna
6lbs light munich
40 quarts RO water(1.5tsp each gypsum and calcium chloride)
21 quarts mash at 150F for 90min
19 quarts sparge at 167F
90 minute boil
estimated OG 1.068 actual OG 1.050

I got exactly 5.5 gallons from the boil kettle so i know my wort isn't diluted. If i'd been having efficiency problems with other malts I would know it was something in my process but this is only happening with vienna mostly, I've only used munich twice both times in conjunction with vienna. Any help is greatly appreciated.

 

[ba-brewer]

If you have a refractometer you can try taking samples of the mash to ensure full conversion. My efficiency dropped a while back and I was able to trace it back to not getting full conversion after switching to conditioning my grain. I now calculate the expected gravity of the mash and wait until I approach that number before sparging.

checkout this site for efficiency information, it was helpful for me.
http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency

 

[doug293cz]

If you have a refractometer you can try taking samples of the mash to ensure full conversion. My efficiency dropped a while back and I was able to trace it back to not getting full conversion after switching to conditioning my grain. I now calculate the expected gravity of the mash and wait until I approach that number before sparging.

checkout this site for efficiency information, it was helpful for me.
http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency

+1

Edit: Looking at the BeerSmith database, Munich & Vienna malts vary widely in diastatic power depending on supplier and darkness. So, depending on which malts you actually used, you might have had insufficient diastatic power for complete conversion.

Brew on

 

[zoomzilla]

THanks for the link. I wasn't aware there was such a difference in base malt diastatic power. Vienna and munich together shouldn't cause a problem, I suppose it's possible the LHBS gave me the 10l munich by mistake. It doesn't give any indication on the bag though. Another possibility is that my brewing software is far overestimating the diastatic power of one or both of the base malts and giving me false hopes.

 

[ba-brewer]

I would guess it is not the software and more to do with the actual grain but what software do you use?

Also do you have your own mill or use the one at the LHBS? If you use the mill at the LHBS it is possible someone messed with the setting.

If the LHBS does not sell a lot of one of those grains and the grain is stored in less than ideal conditions that might effect your efficiency too.

I know a thinner mash is suppose to help efficiency, but maybe with lower diastatic power grains a thicker mash might help keep the enzymes in contact with the starches.

Maybe increase your temp a little to help speed up the conversion.

Take mash gravity measurements and keep notes while limiting your changes per session and you will be able to figure it out.