Help me identify the problem with my gravity!

[lgagnon]

Hello fellow hombrewers, I have a problem with my planned recipe and my measured results in terms of gravity. I need help to identify the problem.
Here is a concrete example, I created a SMASH beer recipe in Brewfather, simple 5kg of 2 row, I use a brewzilla 35L. The software predicts a pre-boil gravity of 1.049 using 75% effeciency as default. I recently bought a double roller grain mill and I set the gap at 0.039. If I try to set the gap less than 0.039 the roller spins and no grains get crushed. So I mashed my 5 kg of grains and I measured the gravity with a refractometer and the reading is 1.032. I added 300 grams of dextrose sugar and my reading is 1.035.

What can I do to improve my effeciency?

 

[TheMadKing]

Hello fellow hombrewers, I have a problem with my planned recipe and my measured results in terms of gravity. I need help to identify the problem.
Here is a concrete example, I created a SMASH beer recipe in Brewfather, simple 5kg of 2 row, I use a brewzilla 35L. The software predicts a pre-boil gravity of 1.049 using 75% effeciency as default. I recently bought a double roller grain mill and I set the gap at 0.039. If I try to set the gap less than 0.039 the roller spins and no grains get crushed. So I mashed my 5 kg of grains and I measured the gravity with a refractometer and the reading is 1.032. I added 300 grams of dextrose sugar and my reading is 1.035.

What can I do to improve my effeciency?

I would first recommend reviewing the various factors that contribute to your efficiency, as well as the difference between conversion efficiency, mash efficiency, lauter efficiency and brewhouse efficiency. Understanding all these terms and their contributing factors will help you immensely in troubleshooting your efficiency.

From the information you've provided here, I'm afraid nobody is going to be able to help you.

Some information that might help are:

-What are you measuring your gravity with?
-what temperature was the wort at when you took your readings?
-how much wort was your preboil volume?
-did you acidify your mash to keep your pH around 5.4?
-did you recirculate your mash?
-If so, Was the recirculation flowing fast or slow?
-how long did you mash?
-what temperature did you mash at?
-is your mash Thermometer calibrated?
-did you sparge?
-If how long did your sparge take?

On your new mill
-how are you measuring your gap at 0.039?
-how are you driving the mill?
-what speed are you running the mill at?

 

[lgagnon]

Thanks for your questions, here are the details

What are you measuring your gravity with? Refractometer with ATC
-what temperature was the wort at when you took your readings? I cooled the liquid to around 20-25C
-how much wort was your preboil volume? 25L
-did you acidify your mash to keep your pH around 5.4? NO
-did you recirculate your mash? Yes,
-If so, Was the recirculation flowing fast or slow? The pump was at maximum
-how long did you mash? 60 mins
-what temperature did you mash at? 65C

I tested with iodine at 60mins of the MASH to make sure the conversion was complete
-did you sparge? Yes
-If how long did your sparge take? 10 minutes

On your new mill
-how are you measuring your gap at 0.039? Feeler gages
-how are you driving the mill? Battery powered drill
-what speed are you running the mill at? 100 to 200 RPM

 

[TheMadKing]

Thanks for your questions, here are the details

What are you measuring your gravity with? Refractometer with ATC
-what temperature was the wort at when you took your readings? I cooled the liquid to around 20-25C
-how much wort was your preboil volume? 25L
-did you acidify your mash to keep your pH around 5.4? NO
-did you recirculate your mash? Yes,
-If so, Was the recirculation flowing fast or slow? The pump was at maximum
-how long did you mash? 60 mins
-what temperature did you mash at? 65C

I tested with iodine at 60mins of the MASH to make sure the conversion was complete
-did you sparge? Yes
-If how long did your sparge take? 10 minutes

On your new mill
-how are you measuring your gap at 0.039? Feeler gages
-how are you driving the mill? Battery powered drill
-what speed are you running the mill at? 100 to 200 RPM

Thanks!

From this info I would immediately suggest slowing your recirculating to as slow as possible, and your sparge should take between 40-60 minutes (assuming you fly sparged?)

Recirculating too fast causes channeling which means you're effectively just mashing part of your grain. You want the water to stay as evenly distributed in your grain as possible, so slow is better for recirculating.

For fly sparging, the force at work that pulls sugar from inside your grain particles into the water is osmosis. Sugar moves from high sugar areas to low sugar areas trying to reach equilibrium. This process takes time. So if you sparge too quickly, you end up leaving a large portion of the sugar behind when you lauter.

Finally, it might be worth looking at your water and mash pH. If your pH is way off, that will affect your efficiency a surprising amount.

 

[lgagnon]

Thanks a lot for the advice! I thought that recirculating was better if it is fast flowing

 

[Brewsmith]

How was the crush? Was it fine enough? If it didn’t crush enough, try running the grain through the mill a second time.

I would agree with the slower sparge runnings.

 

[lgagnon]

How was the crush? Was it fine enough? If it didn’t crush enough, try running the grain through the mill a second time.

I would agree with the slower sparge runnings.

I am not sure about the crush, is it common to run it twice?

How much will it affect effeciency?

That's an option I will certainly consider since my mill won't work with a finer setting

 

[TheMadKing]

I am not sure about the crush, is it common to run it twice?

How much will it affect effeciency?

That's an option I will certainly consider since my mill won't work with a finer setting

I crushed my grain at 0.040 this morning and hit 92.5% mash efficiency, and 87% brewhouse efficiency using a slow recirc and a long slow sparge.

Crushing at 0.039 should be just fine if you can learn to dial in your system for it

 

[lgagnon]

I will recirculate as slow as I can for my next batch.
I will crush twice

Can you be more specific about sparging?

 

[TheMadKing]

I will recirculate as slow as I can for my next batch.
I will crush twice

Can you be more specific about sparging?

I assume your system is designed to fly sparge in a similar manner as the grain father? meaning you pull the grain basket up and then run hot water over the grain to rinse it?

If that's the case, then you'll want to run your water evenly over the top of the grain as slowly as possible. The objective is to keep the water in contact with the grain for awhile so that it can pick up the sugars from the grain. So if you run your sparge water too fast it will just run straight through. It will pick up some sugar, but it will miss a lot too.

Another thing to look at is your mash thickness. The thicker your mash, the more water available for sparging with. I would recommend mashing at 1.25qt/lb to give yourself maximum sparge water.

 

[Brewsmith]

I am not sure about the crush, is it common to run it twice?

Without getting into gap sizes, you will get a feel for it. Look at the grain every time and even feel it. Are there empty husks and uniformly broken kernels? Are there large, unbroken pieces? It should be finer. Is it a lot of flour? Too fine, back off the crush.

Some grains are different sizes. I find that rye can sometimes not get crushed very well while the barley goes through fine. I’ll often double mill the little amount of rye in a recipe but mill everything else just the once. Most of it just comes down to experience and knowing your system and equipment.

The short answer is just brew more and more. You’ll get there

 

[lgagnon]

Here is an update on my previous post, I tried adjusting the space of the roller on my mill but when I reached a certain point the roller would just spin and no grain would be crushed. So I decided to set it and mill my grain twice. I also used the recommendation to set the flow of the pump to a minimum. I also sparged very slowly (8 litres).

Here are the results
In my Brewfather recipe I set the effeciency to 70% and pre-boil gravity was planned to be 1.044
The real result was 1.052
I will post the post-boil gravity in about 2 hours!

Thanks a lot for all the input!!