Brewzilla mash help

[primalyeti]

Hey everyone

What grain thickness do you usually use on the brewzilla, I've been going with 4.5L\kg to avoid having to sparge as much.

Also, I've been stirring almost constantly during the mash, with the pump on, is this okay or should i let it sit?

Wondering if either of these is killing my efficiency

 

[doug293cz]

Hey everyone

What grain thickness do you usually use on the brewzilla, I've been going with 4.5L\kg to avoid having to sparge as much.

Also, I've been stirring almost constantly during the mash, with the pump on, is this okay or should i let it sit?

Wondering if either of these is killing my efficiency

So, just what are your:

• Conversion efficiency
• Lauter efficiency
• Mash efficiency

Hard to say if you really have efficiency issues, if you don't tell us where you're at.

Brew on

 

[primalyeti]

That's fair, haha! Sorry, that was a late night post

Mash Eff was 68% on my last brew.

Only done 2 so far

 

[doug293cz]

That's fair, haha! Sorry, that was a late night post

Mash Eff was 68% on my last brew.

Only done 2 so far

Ok, that's most likely less than optimal. In order to determine why, we need to know whether your conversion efficiency is low, your lauter (sparge) efficiency is low, or if both are low.

Conversion efficiency is measured using the method here. If it is less than 90% then you should address it. Good conversion efficiency is 95% or better, and 100% is achievable.

Most brewing software will calculate your mash efficiency for you, but a lot of the software available does not correct for grain moisture content (which can make your efficiency appear about 4% lower than it actually is.)

Once you have your mash efficiency and your conversion efficiency, you calculate your lauter efficiency as:

Lauter efficiency = Mash efficiency / Conversion efficiency​

​

Lauter efficiency is always less than 100% (because you can't get all of the wort out of the grain mass.) Lauter efficiency is also highly dependent on your sparge process and grain absorption rate (unless fly sparging.) To determine if your lauter efficiency is "too low" compare your efficiency to the chart below.

Grain absorption for traditional MLTs and batch or no-sparge is about 0.12 gal/lb. If you squeeze after draining you can get lower absorption rates (common with BIAB.) Good fly sparging will give you lauter efficiency slightly above the solid green line. If your fly sparge isn't better than the solid orange line, than you would be better off batch sparging.

Low conversion efficiency is primarily due to your mash time being too short to convert all of the starch in your grits. Larger grits take longer to convert than smaller grits. The easiest fix for poor conversion efficiency is to crush finer (to the point that any finer will give you stuck mash/sparge problems.) Once your crush is as fine as your process will allow, the only other thing to do to increase conversion is to mash longer. Note that a mash out has the effect of mashing longer, at a higher temperature which speeds things up - until the enzymes are denatured.

Correcting lauter efficiency problems depends on whether you are batch/no-sparging or fly sparging.

Low efficiency when fly sparging is almost always due to the sparge water channeling thru the grain bed, and not rinsing all the grain. Slowing the sparge rate is usually the best way to minimize channeling.

Low efficiency when batch sparging is usually due to failure to adequately stir the mash prior to initial run-off, and/or inadequate stirring after adding the sparge water.

Brew on

 

[primalyeti]

I can't calculate that unfortunately as I only took my first SG reading after the mash and sparge, so whatever was going into the boil.

 

[doug293cz]

I can't calculate that unfortunately as I only took my first SG reading after the mash and sparge, so whatever was going into the boil.

For future reference, here are the items you should record if you really want to know what's going on with your efficiency:

• Grain bill weight
• Weighted average grain potential
• Strike water volume
• End of mash SG after homogenizing all the wort in the mash
• First runnings volume (if batch or no-sparge)
• Pre-boil volume
• Pre-boil SG after homogenizing all the wort
• Post-boil volume
• Post-boil SG (i.e. OG)

Accurate volume measurements are critical to accurate efficiency calculations. For the most accurate results, all volume measurements should be corrected for expansion to a standard temp (68°F/20°C is the ASBC standard temp for measurements.) Wort shrinks about 2% cooling from 150° to 68° and about 4% cooling from 212° to 68°.

Brew on

 

[primalyeti]

For future reference, here are the items you should record if you really want to know what's going on with your efficiency:

• Grain bill weight
• Weighted average grain potential
• Strike water volume
• End of mash SG after homogenizing all the wort in the mash
• First runnings volume (if batch or no-sparge)
• Pre-boil volume
• Pre-boil SG after homogenizing all the wort
• Post-boil volume
• Post-boil SG (i.e. OG)

Accurate volume measurements are critical to accurate efficiency calculations. For the most accurate results, all volume measurements should be corrected for expansion to a standard temp (68°F/20°C is the ASBC standard temp for measurements.) Wort shrinks about 2% cooling from 150° to 68° and about 4% cooling from 212° to 68°.

Brew on

So question on some of those:

• What is the "weighted average grain potential" ?
• Can you explain "End of mash SG after homogenizing all the wort in the mash" ? Is that essentially the SG of the wort pre boil but after sparge?
• "First runnings volume" is that amount of wort before sparge water being added?

Some of those metrics I actually do have from my last session

 

[doug293cz]

So question on some of those:

• What is the "weighted average grain potential" ?

It's the sum of each grain weight times that grain's PPG divided by the total grain weight. So if you have 9 lbs at 37 ppg and 1 lb at 25 ppg the weighted average potential is:​

(9 * 37 + 1 * 25) / (9 + 1) = (333 + 25) / 10 = 35.8 ppg​

• Can you explain "End of mash SG after homogenizing all the wort in the mash" ? Is that essentially the SG of the wort pre boil but after sparge?

It is the SG of the wort in the mash BEFORE adding any sparge water. This is the SG value needed to calculate conversion efficiency. The wort needs to be homogenized so that low SG wort not in contact with the grain (above, below, outside a malt pipe, etc.) is mixed in with the high SG wort in the grain mass. If you don't homogenize, then the SG measurement can be too high or too low, depending on where the sample is taken from. The best way to homogenize depends on your mash hardware configuration.​

• "First runnings volume" is that amount of wort before sparge water being added?

Yes. If you are batch sparging it is the volume collected after the first draining, before adding any sparge water. It is used to calculate the grain absorption rate as follows:​

Grain Absorption Rate = (Strike Water Vol - First Runnings Vol) / Total Grain Wt​

You need to know the absorption rate in order to do your starting water volume calculations. This is not applicable to fly sparging.​

​

Some of those metrics I actually do have from my last session

Brew on

 

[rjhoff]

How are you crushing grain? I found that a tight mill gap improves mash efficiency on the Robobrew/Brewzilla. I believe I’m at 0.032” right now.

 

[primalyeti]

How are you crushing grain? I found that a tight mill gap improves mash efficiency on the Robobrew/Brewzilla. I believe I’m at 0.032” right now.

Oh, I just get my LBS to mill them for me. I can investigate what setting they have it set to