Extremely inconsistent efficiency

[MikeFallopian]

Recently I've been experiencing problems with efficiency. I've been brewing for about 5-6 years on the same equipment. Up until about a year ago my efficiency was consistently between 75 and 80%, but recently it has been very unpredictable.

For example, my last two brews were a Kolsch and an Altbier, and both hit the target OG. However, I made an IPA today and was 12 points below my target! I was very careful today and made sure I hit all my numbers, batch sparged slowly, and had a constant rolling boil.

As I'm using the same the gear* and process for each mash, would I be correct in thinking that grain crush might be the issue? I use different suppliers/manufacturers for different grains so I feel that inconsistent grain crush is the culprit. Interestingly, my father-in-law has also started to experience the same problem, yet had consistent mash efficiency before hand.

*my mash tun is a converted picnic cooler with a braided hose filter.

 

[eric19312]

Crush is a likely culprit especially since it sounds like nothing else is changing.

 

[Boleslaus]

Are you noticing a drop in efficiency in relation to increasing OG? It is typical to have lower efficiency with increased grain bills. I ask because the 2 beers you mentioned were Kolsch and Alt, then you brewed an IPA.

However, you did say you hadn't had this problem before.

 

[doug293cz]

Crush is a likely culprit especially since it sounds like nothing else is changing.

Are you noticing a drop in efficiency in relation to increasing OG? It is typical to have lower efficiency with increased grain bills. I ask because the 2 beers you mentioned were Kolsch and Alt, then you brewed an IPA.

However, you did say you hadn't had this problem before.

Both of these are possibilities.

Since mash efficiency = conversion efficiency * lauter efficiency, you need to know whether your issue is with conversion or lautering. Crush primarily affects conversion efficiency, because small grits convert faster than larger grits. Grain bill size primarily affects lauter efficiency, because the larger grain bill retains more wort, and thus more sugar, in the mash.

The effect of grain bill size on lauter efficiency can be calculated for batch (or no) sparge, and typical results are shown in the chart below:



You can determine degree of conversion during the mash by measuring the SG of the wort in the mash by using the method described by Kai Troester here. Be sure to stir the mash before taking an SG sample.

Brew on

 

[MikeFallopian]

Are you noticing a drop in efficiency in relation to increasing OG? It is typical to have lower efficiency with increased grain bills. I ask because the 2 beers you mentioned were Kolsch and Alt, then you brewed an IPA.

However, you did say you hadn't had this problem before.

Interesting - this is a possibility that I hadn't thought of. However, I've brewed high gravity beers in the past with no real problem in hitting my target OG.

 

[MikeFallopian]

Both of these are possibilities.

You can determine degree of conversion during the mash by measuring the SG of the wort in the mash by using the method described by Kai Troester here. Be sure to stir the mash before taking an SG sample.

Brew on

Thanks for this! Next brew I'll try to identify whether it's a conversion or lautering issue.

 

[MikeFallopian]

Both of these are possibilities.

Since mash efficiency = conversion efficiency * lauter efficiency, you need to know whether your issue is with conversion or lautering. Crush primarily affects conversion efficiency, because small grits convert faster than larger grits. Grain bill size primarily affects lauter efficiency, because the larger grain bill retains more wort, and thus more sugar, in the mash.


Brew on

If my issue does turn out to be lauter efficiency on larger grain bills, is there a way of improving my efficiency during the sparge?

 

[eric19312]

If my issue does turn out to be lauter efficiency on larger grain bills, is there a way of improving my efficiency during the sparge?

Yes - sparge with more water. This will bring up lauter efficiency but you either are back to medium gravity beer or have to boil longer--maybe much longer. Better bet with bigger beers is to plan for reduced lauter efficiency and increase the grain bill accordingly.

 

[doug293cz]

If my issue does turn out to be lauter efficiency on larger grain bills, is there a way of improving my efficiency during the sparge?

To get maximum lauter efficiency when batch sparging you want to do the following.

• Stir sufficiently to get a uniform concentration throughout the mash. If the sugar concentration in the mash isn't uniform, then the wort held by the grain is the highest in sugar.
• Vorlauf
• Drain MLT completely, tilting if necessary to minimize undrained wort.
• Add sparge water and stir until uniform concentration.
• Vorlauf
• Drain MLT completely.

The calculated efficiencies I posted earlier assume all of the above has been done optimally.

You can gain an extra 2% - 4% lauter efficiency by splitting your sparge volume and doing to sparges. Unfortunately the improvement is less for larger grain bills, and more with smaller grain bills.

And, as @eric19312 said, you can use more total brewing water (allocated mostly for sparging), and then boil longer to get your target volume.

Brew on

 

[eric19312]

Most important thing about efficiency is reproducibility. You want to minimize process differences so the actual resulting efficiency is determined by your the size and composition of your grain bill. What @doug293cz mentions above is important - have a procedure for lautering and follow it same way every time. Getting your grain milled the same way every time will also help. Easiest to do this on your own mill which you calibrate from time to time.