Robobrew - struggling with efficiency

[barts1971]

I switched to all grain about a year ago when I bought a used Robobrew (early gen). It has no pump but works very well otherwise and allowed me to start to experiment with all grain brewing which I have really enjoyed.

The issue I am having is with efficiency. I have been ordering pre-milled kits from Morebeer.com and mashing in the Robobrew but the last two brews have been about 10-15 points below expected S.G. I did add a pound of rice hulls to the last batch but still found the mash efficiency to be lower than I would have liked. I was able to get higher S.G. in the past and maybe it's because I spent more time sparging. In those brews, after adding all the sparge water, I ran wort out of the faucet on the Robobrew into a pitcher and slowly poured that back over the grain bed. I did this for about 45 minutes so it was very time consuming.

Having brewed yesterday and experienced this again, I will share my brew stats in case anyone has any thoughts.

Style - Porter
Grain bill - 12.4 pounds (added 1 pound of rice hulls)
Mash water - 4.25 gallons
Mashed at target 152 (fluctuated from 152-159 during mash)
Mash length - 60 minutes
Sparge water - 4.5 gallons (lifted the drum and poured 170 degree water over the top letting the wort drain through until I had the necessary volume)
Boil time - 60 minutes
Pre-boil wort produced - 6.75 gallons
5.25 gallons in fermenter
Expected O.G. - 1.050-55
Actual O.G. - 1.034

I am wondering whether the grist of the grain may not be satisfactory since it is pre-milled? I am also wondering if I am significantly hampered by not having a pump and am curious about the primary function of it during the mash. Should I go back to my pour over method that I was doing before (described above)?

I am happy with the taste, color and clarity I am gettting but would like a little more body in my brews. Is there anything else I can do to improve my mash efficiency and increase my S.G.?

Thanks in advance for any help.

Cheers!

 

[mac_1103]

I am wondering whether the grist of the grain may not be satisfactory since it is pre-milled?

I think that you're absolutely right to wonder about that. There are plenty of recent posts complaining about Morebeer's grain crush.

 

[Broken Crow]

I've seen the recent threads about the morebeer crush and while I can't comment on that: If you want to make your recirculation easier you could add a pump.... here's the same base unit in the US that you get with a brewzilla, vevor or other AIOs:
https://www.ebay.com/itm/236118646595?_skw=brew+pump&itmmeta=01JYCHSS7XVYJBC33T4HD3Q1RF&hash=item36f9c49f43:g:tcAAAOSw9gloMZ7I&itmprp=enc:AQAKAAAA8FkggFvd1GGDu0w3yXCmi1d8DY1sffkLYJvmnHzLJeJ2Gh6eHdYm+tWf72eEIyfRsTOlgdza+NWovUAIRxPK2CP5V3tWCJ0a2ARlzIty6e6ZqAJkIYM8Hcao+kz2xS8fv2NrlZTXzlFoTvZdHX7bePW/UEdFOKTO9gwzDlQBZ8/FU7OIY4NYQ/10hGIjne3gnesNQ1fD5uMjNnRb36G8DpQrORj6Zg2GTB3FBuuGLFMnrQ7eKxB96z+Z2zlrpIGOQlueA6rBcEM/tjK6eEVdvaKiEfpNlqFJocFQUu6dxaWcmZhFvRWDPfZCfIzgeIL54w==|tkp:Bk9SR5yU55HzZQ
..only it has a stainless steel head and no wingnuts like the Anvil version. Have you considered adding a pump?

 

[barts1971]

Thanks for the comments!

@Broken Crow I have thought about upgrading to a Brewzilla Gen 4.1 to get, among other things, the pump. What is the true value of the pump and does it make a measurable difference? Maybe the answer is to add a pump to my existing setup to begin with?

@mac_1103 I read up on this in the threads and it certainly seems to be suspect. I have also thought about adding a mill to my set up to crush my own. Based on the comments I was reading, it seems that this may make a big difference. I hate to add more time to my brew day but if it will help produce a better end result, I'm down. Any thoughts on this and recommendations for a reasonably priced but durable and functional mill?

If I were to add either a pump or a mill to my system, which would yield the greatest potential impact?

 

[IslandLizard]

you could add a pump.... here's the same base unit in the US that you get with a brewzilla, vevor or other AIOs:
https://www.ebay.com/itm/2361186465...WcmZhFvRWDPfZCfIzgeIL54w==|tkp:Bk9SR5yU55HzZQ

Mind, that linked pump is a 220V (240V) model!

Besides, I doubt using recirculation is going to fix the OP's issue.

Having brewed yesterday and experienced this again, I will share my brew stats in case anyone has any thoughts.

Obtaining a much better crush may help, but there are some other issues that can be fixed.

For one, your strike and sparge volumes are not optimal.
Here's a very recent thread that gets into some of the details:
https://www.homebrewtalk.com/threads/question-about-my-mash-efficiency.736593/#post-10467442

 

[barts1971]

Great feedback, thanks. I was using the Morebeer water calculator but there are a bunch of variables in it which I'm sure I screwed up.

 

[Happy Tails Brewing]

I would guess you have four options to improve efficiency. One as you mash drain some wort from the bottom of your system and gently pour over the top. Two buy kit/grains from a source that will give you a finer crush. Three buy a pump and hose to recirculate during the mash. Four buy a grain mill to control your crush. Different cost and drawbacks to each of these, but they should all help. If you get the proper crush, water to grain ratio, and recirculation combined would give you the best results.

 

[rmr9]

One thing I started doing with mine during the sparge is putting the rubber cover/stopper thing over the central tube and slowly pouring the sparge water over the top of the grain. I noticed that I had a fair amount of sparge water sneak down the little central pipe.

I agree your volumes may be a bit high, but I typically mash in with 6.25-6.5 gallons and sparge with 2 gallons. I’ll typically get an OG of 1.050-1.055 on a 12lbs grist. Maybe try some of those adjustments in addition to the excellent ones above.

 

[IslandLizard]

Just for your reference, you should be able to get 5 gallons of a 1.060 (OG) Porter out of 12.4# of grist, with a 60' boil.
That's with a properly (somewhat finely) milled grist. You would not need rice hulls.

Pour-over sparges don't work well. A dunk sparge of some sort (using a separate vessel to dunk your drained grist into) would be better.

 

[hungupdown]

When doing a fast sparge, that will rinse sugars off the surfaces of the grain particles. But few of the free sugars within the larger particles, have time to diffuse out.
That effect becomes greater, the thicker the mash.

With 12lb grain, the grains would absorb around 1.5 gal of water, (and from 4.25 gal mash water, there's 2.75 gal that's not absorbed).

At end of mashing. The sugar density in the wort, and within the grain, will be fairly similar. As sugars have had time to diffuse out of the grain.
At that point, 1.5 ÷ 4.25, or 35% of the sugar solution is within the grain.

If your robobrew uses a solid wall malt pipe. The unused water sitting in the gap around the pipe, makes things worse. If 0.5 gal in gap, then it's 1.5 ÷ 3.75 =40%

A fast sparge might allow time for the sugars in flour and fine particles to diffuse out. The amount recovered, would depend on crush size.
Laboratory tests, can get 100% extraction efficiency, but use 100% flour (including the ground husks).

A full volume mash, with the 8.75 gal. Gives 1.5 ÷ 8.75 = 17% sugars left within grain..

I like a thin mash, around batch volume, with a small sparge to wash off the surface sugars. So split mash: sparge water 4:1 or 2:3

But if you like a thick mash, you could do a 'floating' sparge. Slowly drain off the wort (into pitcher etc), as you add sparge water at the same rate. Keeping the grain bed submerged, as long as possible.
Optional: closing drain once final sparge water is in, and letting the grain soak in fresh water for a while, can give higher efficiencies.

Once, when forced to pause a brew mid session, and leaving it for a 3 hour floating sparge, I got 90% mash efficiency (normally 78 ish% on my BZ g4 with batch sparge).

Brulosophy exBEERiment | Grain Crush: Coarse vs. Fine. Comparing full volume BIAB with coarse and fine crushes, found fine crush gave OG 10 points higher.

 

[Whisky River]

I think others have already mentioned a lot of the important factors but I’ll try to add a little explanation on a few points.

Recirculation can help with efficiency by equalizing the temperature throughout the mash. Without recirculation you often get very hot wort at the bottom near the heating element and cooler grain on top. By recirculating the wort you are distributing the heat throughout the mash ensuring all of your grain is at the correct mash temperature. Manually draining and pouring hot wort over the top of the grain bed can help somewhat but will probably be less effective than constant recirculation with a pump.

A finer grain crush can also help by speeding up some of the processes that happen during the mash. If you can’t find somewhere to crush more finely you might try lengthening your mash to 90 minutes. The larger the grain bits, the longer it takes for the enzymes to get into them and do their work completely.

I don’t think your previous method of sparging with your first runnings of wort will help much so you can probably skip that if it saves you time. Once that wort is saturated with sugar it won’t really absorb more sugar from the grains, but using clean water will.

Also, when calculating your mash and sparge water try to pick the mash thickness you think will work best for you, maybe that’s 1.5 or 1.75 qts/lb and then don’t forget to add to that the amount of liquid that is under the mash pipe. Remember you have to fill up that “recoverable dead space” with liquid first and then once you are above that line and in the mash pipe, then the water you add is mixing with the grain and determining your mash thickness. If you forget to add the recoverable dead space, the amount of water you add will not be enough for your desired thickness and your mash will be too thick.

Finally, you say that for your sparge you” lifted the drum and poured 170 degree water over the top letting the wort drain through until I had the necessary volume”. And it looks like you used 8.75 G and ended up with 6.75 G. Assuming somewhere between .1-.125 gallons per pound for grain absorption for 12.4 pounds of grain that is between 1.2-1.5 gallons absorbed in the grain. It seems like there might still be anywhere from 1/2 to 3/4 of a gallon missing. Did you stop sparging and leave a lot of water behind?

 

[mac_1103]

Any thoughts on this and recommendations for a reasonably priced but durable and functional mill?

Everybody has their own definition of "reasonably priced." I use a cheap corona mill. Because I'm cheap.

 

[Halfakneecap]

I recently had issues in my robo. This was around 85 batches in, and after no real issues previously.

I had changed my grain mill setting for a different brand grain. What a nightmare. Well, not really, i just had to note down mill gap settings and adjust for different brands, and grain ( wheat for example ).

I have had a grain mill for at least a decade and really never had any problems with crush and efficiency, so i didn't really take notice of the settings closely up until recently.

 

[DuncB]

As has been mentioned many times, physically inspect your crush early in the milling process.

 

[IslandLizard]

Once, when forced to pause a brew mid session, and leaving it for a 3 hour floating sparge, I got 90% mash efficiency (normally 78 ish% on my BZ g4 with batch sparge).

That sounds like effectively being a "batch sparge," alas for an extended time, more than merely "rinsing" the sugars out. Depending on the "sparge" volume and the temps it was held at for those 3 hours, it may have been effectively an extended mash.

 

[doug293cz]

The issue I am having is with efficiency. I have been ordering pre-milled kits from Morebeer.com and mashing in the Robobrew but the last two brews have been about 10-15 points below expected S.G. I did add a pound of rice hulls to the last batch but still found the mash efficiency to be lower than I would have liked. I was able to get higher S.G. in the past and maybe it's because I spent more time sparging. In those brews, after adding all the sparge water, I ran wort out of the faucet on the Robobrew into a pitcher and slowly poured that back over the grain bed. I did this for about 45 minutes so it was very time consuming.

With this process, you did not sparge at all. By adding additional water, and then homogenizing the wort with manual recirculation, you just did a full volume mash the hard way. Sparging is rinsing with fresh water, after you have drained the initial wort, or concurrently while draining the initial wort but without any stirring or recirculation. The purpose of sparging is to rinse additional sugar from the surface (and maybe interior) of the grits.

Unless you mashed out prior to adding your dilution water, then what you did was effectively extend the mash time, which would allow additional conversion of starch to sugar to occur, if conversion was not complete at the end of your initial mash. This is very likely the reason for the better efficiency of your "old" process. It's an indicator that your mash times are too short to get complete conversion at the mash temp and crush size that you have. Coarser crushes take longer to convert than finer crushes. Thus going to a finer crush can give you better conversion efficiency for the same mash time (all else being equal.)

Having brewed yesterday and experienced this again, I will share my brew stats in case anyone has any thoughts.

Style - Porter
Grain bill - 12.4 pounds (added 1 pound of rice hulls)
Mash water - 4.25 gallons
Mashed at target 152 (fluctuated from 152-159 during mash)
Mash length - 60 minutes
Sparge water - 4.5 gallons (lifted the drum and poured 170 degree water over the top letting the wort drain through until I had the necessary volume)
Boil time - 60 minutes
Pre-boil wort produced - 6.75 gallons
5.25 gallons in fermenter
Expected O.G. - 1.050-55
Actual O.G. - 1.034

With the appropriate data, it is possible to calculate your conversion efficiency, and if it is less than 100%, then your mash time is too short for your conditions. The best data to work with is the end of mash SG prior to any sparging, and after good homogenization of the wort, plus the grain bill weight, the weighted grain potential of the grain bill, and the grain bill's weighted average moisture content. Moisture content is the least important, and assuming 4% if you don't have actual data will get you close. Mash efficiency is equal to conversion efficiency times lauter efficiency, so if conversion eff is less than 100%, it will negatively impact your mash efficiency.

If you don't have an end of mash SG measurement, then with some assumptions you can use pre-boil volume and pre-boil SG, or post-boil volume (in kettle volume, not to fermenter volume) and post-boil SG (OG), along with the grain bill information to estimate conversion and lauter efficiency.

Do you have any of the missing data that you can provide? If so, I can do an analysis to see if poor conversion efficiency is a significant part of your low overall efficiency issue.

Brew on

 

[DavidBD]

There are plenty of recent posts complaining about Morebeer's grain crush.

The batch I brewed last Friday had a disappointing OG of 1040, when it should have been 1050. A significant part of the grain bill included some lovely T. Fawcett malts (Otter and Pearl), which came pre-milled from Morebeer. The malts are nice, fresh, with great friability and amazing smell, but the kernels are small and they don't look properly crushed. This experience put me in the market for a grain mill.

 

[Halfakneecap]

The batch I brewed last Friday had a disappointing OG of 1040, when it should have been 1050. A significant part of the grain bill included some lovely T. Fawcett malts (Otter and Pearl), which came pre-milled from Morebeer. The malts are nice, fresh, with great friability and amazing smell, but the kernels are small and they don't look properly crushed. This experience put me in the market for a grain mill.

I've had both expensive grain mills and cheap ones. Both worked great. My current one is a single roller cheap one, and it's fine

 

[Bobby_M]

I don't know how many times it needs to be said. Morebeer perhaps intimidates the grain, but it's a bluff. They do not crush it anywhere close to enough. If you say efficiency problems and morebeer in the same post, stop there. We found your problem

 

[barts1971]

Thanks for all the notes. I don't have end of mash SG. Pre boil volume was 6.75 gallons. Post boil volume was 6.37 gallons and post boil OG was 1.034.

Grain bill:
5 lb Briess 2 row
5 lbs Viking 2 row pale
12 oz Baird Choc
8 oz Briess Carapils
8 oz Briess Caramel 120L
8 oz White Wheat
1 lb Rice Hulls

Based on the comments above, I think I am mashing too short a time (60 minutes as instructed by Morebeer) and the grain crush could be a problem. I am also wondering if I have enough water in my mash as it was just at the top of the grain bed.

What shoudl the mash look like (how much water) and how long is recommended? Can you mash for too long?

I kegged the Porter yesterday and, while light bodied, the flavor is very good. Still very drinkable, just not in the ABV and body range for the style.

Any thoughts on how to improve my process are appreciated.

 

[rmr9]

Thanks for all the notes. I don't have end of mash SG. Pre boil volume was 6.75 gallons. Post boil volume was 6.37 gallons and post boil OG was 1.034.

Grain bill:
5 lb Briess 2 row
5 lbs Viking 2 row pale
12 oz Baird Choc
8 oz Briess Carapils
8 oz Briess Caramel 120L
8 oz White Wheat
1 lb Rice Hulls

Based on the comments above, I think I am mashing too short a time (60 minutes as instructed by Morebeer) and the grain crush could be a problem. I am also wondering if I have enough water in my mash as it was just at the top of the grain bed.

What shoudl the mash look like (how much water) and how long is recommended? Can you mash for too long?

I kegged the Porter yesterday and, while light bodied, the flavor is very good. Still very drinkable, just not in the ABV and body range for the style.

Any thoughts on how to improve my process are appreciated.

I think taking most of the advice from above is the best bet. Better/more fine crush of your grains, if you want to mash say 90 minutes you can but I’m not sure you have to. Given your boil off rate, up it to a 90 minute boil.

My approach is to use 6-6.5 gallons in the mash and 2-2.5 gallons sparge. It seems to work for me, but you may need to tweak that a bit. I’ve gotten it to where I can fairly consistently get a wort of ~1.050 using 8.5 gallons total.

You can probably ditch the rice hulls as well.

 

[rmr9]

Also if you don’t have access to a grain mill or don’t want to spend money on it now, I would buy an extra pound or 2 of base malt to make up for the efficiency loss.

But increasing boil time and adjusting your water volumes could make a big difference.

 

[barts1971]

Thanks. I'm going to try those suggestions on my next batch and see if I can improve my efficiency. Now, I just need to "relax, don't worry and have a homebrew."

 

[DuncB]

Some homebrew suppliers have the option for BIAB crush and normal crush.
A mix of these two crushes might help, when I was dialling my crush in on my mill I increased the finer crush for part of the bill to see its' effect.

 

[Bobby_M]

I was able to get higher S.G. in the past and maybe it's because I spent more time sparging. In those brews, after adding all the sparge water, I ran wort out of the faucet on the Robobrew into a pitcher and slowly poured that back over the grain bed. I did this for about 45 minutes so it was very time consuming.

This suggests that you just effectively extended your mash conversion time which was the real reason the gravity was higher but you did lose the efficiency boost of a true sparge because you completely homogenized the mash wort. I can see a few people mentioned this already.

Get your grain from a shop that will actually mill the grain to a usable condition. It's impractical to buy grain from me in NJ but I'm sure there has to be a shop on the west coast that will take some direction on their mill gap. If that's not the case, get yourself a used mill. A lot of people getting out of the hobby so they're out there.

Mash a bit thinner. Shoot for 1.5 quarts per pound of grain or whatever fits in your brewing system. Any amount you need to add back in as a sparge, the closest thing you can do to a true fly sparge is to pour the water in to the top of the malt pipe as you slowly pull it upwards. It's kind of hard to do without hooking up a rope pulley. If you don't have one, just pour it in with one hand as you lift with the other, always keeping a layer of water above the grain.

Get yourself a refractometer and don't end the mash if the mash wort gravity is still rising. If you keep using really poorly crushed grain you need a much longer mash. If you get a mill or a better supplier, you'll be able to shorten the mash but always rely on measurements not time.