Efficiency all over the place on my new gravity rig

[ScroatesMcGoats]

Hey everyone,

I made the switch to allgrain brewing a few months ago, and just brewed my 4th batch on it. It is a 5 gallon igloo HLT, 10 gallon Igloo Mash tun with false bottom, and then either my kettle or keggle. My first batch was a stout, which I got 50% efficiency on. I figured I fly sparged too quickly, so on my second batch, an IPA, I did a very slow sparge and got around 75% efficiency. On my 3rd batch, a pale ale, I got 1.058 for a pre boil gravity reading (90% efficiency), but then after I was done brewing, the OG was 1.060...only .02 higher?

Anyways, just finished brewing my Gose with a 1.035 goal at 75% efficient, and ended with a 1.020, which was about 48% efficient. I did a slow fly sparge, stirred the mash real good before and after the mash, and mashed the malts at 146 for 90 min (previous mash's were 60 min). This was a grain bill of 4lbs german pils, 3lbs german wheat, 1lbs carapils, and .5lbs flaked rice.

Any idea what would be causing such a low efficiency?

 

[ba-brewer]

Are you doing anything to measure conversion? I use a refractometer to measure the gravity of a mash and don't sparge until the mash is over 95% converted. I made a spreadsheet with the information in palmer "How to brew" book and do a quick calculation to know what my target gravity is for the day.

What are you doing or using to measure mash temp? If you are on the low end of mash temps(150 and lower)it will take longer to convert.

Maybe try a couple batch sparge brews. Batch sparging is bit more predictable. ​

If you want to fly sparge I would not stir past 20min or 30min to allow the grain bed to settle.

 

[ScroatesMcGoats]

I use a hydrometer to measure my gravity readings. I could never tell if I was supposed to adjust my preboil gravity for temp or not...here is the tool I use.

https://www.brewersfriend.com/allgrain-ogfg/

Digital thermometer, stick it right in the mash. I did a 90 min mash this go around because of the lower temp, as I am going for a nice dry Gose.

Are you measuring your mash gravity before sending it to the kettle? Problem I have is that when you fly sparge, its one continuous process, so seemingly no way to go back and correct it. I stir at the end of the mash and then do 2-3 vorlauf's to seat the grain bed before beginning the boil process.

 

[mongoose33]

As usual, the first place to look is at your crush. If your crush is leaving whole grain kernels, that's a big part of the problem.

Another issue might be the water. How are you dealing with that? If the water produces pH way out of spec, that could be part of the issue.

A third is the fly sparging. I'm not sure why anyone brewing 5 gallons would fly sparge, as the incremental cost in grain in doing a batch sparge is minimal. A batch sparge is also easier and faster. Yeah, you leave a little sugar behind, but up the grain bill by 10 percent and that probably will be enough.

Finally....why a mash temp of 146? That's really low. Lower temps will tend to make a more attenuative beer, which is counter to your experience in efficiency. That suggests to me that it's something like the crush or the water that's the problem.

 

[bracconiere]

i'd say on the last batch, did you boil the flaked rice first to gel the starch for conversion? rice doesn't gel at mash temp needs to be boiled...

not sure if flaked is the same but i know that it's true for rice....

edit: didn't see the period before the 5, thought it was 5 lbs....not a half pound...

 

[ESBrewer]

I would check the actual temperature (thermometer measurement error may lead to problems, especially when mashing low (or high)), grain crush, pH (your gose is a grain bill that would typically result in high mash pH values unless adjusted). When fly sparging, an even flow through the grain bed is important and depends on the type of manifold. But this did probably not change between the batches.

And what bracconiere said, some grains have higher gelatinization temperature than others so you may need to consider this when doing a low temp mash. Flakes are usually gelatinized during manufacturing process whereas whole grains are not. Wheat protein also tends to precipitate in the mash and sometimes it may clog the mash so that sparging and conversion is affected so gose is definitely a more challenging mash compared to 100% barley recipes.

 

[ba-brewer]

I use a hydrometer to measure my gravity readings. I could never tell if I was supposed to adjust my preboil gravity for temp or not...here is the tool I use.

https://www.brewersfriend.com/allgrain-ogfg/

Digital thermometer, stick it right in the mash. I did a 90 min mash this go around because of the lower temp, as I am going for a nice dry Gose.

Are you measuring your mash gravity before sending it to the kettle? Problem I have is that when you fly sparge, its one continuous process, so seemingly no way to go back and correct it. I stir at the end of the mash and then do 2-3 vorlauf's to seat the grain bed before beginning the boil process.

I measure the gravity before I start the sparge. With a refractometer I just take a few drip from a spoon I dip into the mash tun.

If you use a hydrometer you should cool your sample down to close to the calibration temp or you need to make correction to gravity for temp. Not really sure how accurate the value would be at double the normal calibration temps.

When I used a cooler I would vorlauf until the wort comes out pretty clear instead of a set number.

A few quick stirs is all you need to mix things up, if you stir too much you will drop the temp. A quick stir at 10 or 15 mins then another at 30min is all you really need.

Like mongoose said crush can have a big impact. I am assuming you are buying the grain crushed or having it done at the LHBS as you are just starting out. Are you getting the grain and crushing within few days of brew day? I would not let crushed grain sit around for very long, mostly just from a quality stand point but more than a weeks or two may have impact on the viability.

 

[ba-brewer]

A third is the fly sparging. I'm not sure why anyone brewing 5 gallons would fly sparge, as the incremental cost in grain in doing a batch sparge is minimal. A batch sparge is also easier and faster. Yeah, you leave a little sugar behind, but up the grain bill by 10 percent and that probably will be enough.

I started fly sparging a little while back for my 5gal batches, not really a grain saving thing but more for wort clarity and time. In my RIMS setup it takes a while to rerun clear when adding batch sparge water. I have a domed false bottom so I need to drain slow anyways to not break the vacuum and it was taking almost as long a fly sparge anyways so just started doing it.

I do agree batch sparging is easier. If my RIMS cleared up as fast as my cooler used to I would probably still be batch sparging.

 

[ScroatesMcGoats]

I didnt do anything with the flaked rice differently, as the half pound was just supposed to help with sparge.

Admittedly, I dont measure my waters quality or PH, just use tap and hope for the best usually.

My fly sparge is a round copper setup that is slightly smaller than the 10 gallon cooler opening. Always keep a 2 inch or so level on top of the set grain bed as it completes. I always vorlauf until clear, which tends to be 2-3.

Thermometer has been tested to make sure for accuracy.

I crush my grain at the LHBS until I can buy my own mill.

Still not sure what could have gone wring, unless it really was the crush. Cant imagine .5lbs of rice would congeal the mash, and the temp and longer mash should have resulted in a higher than normal gravity reading.

 

[ScroatesMcGoats]

I think I may have figured out my problem....looks like I got a bad reading on the pre boil OG. To correct for the loss, I added 2.5lbs of extract to the batch, but ended with an OG of 1.062...much higher than I wanted. I normally take my sample with a wine thief, but actually took a sample this time with a test tube by taking wort right from the very top. I am guessing since I did not stir the wort, this may have been the final runoff from the mash.

Based on the calculations, looks like I had more like 70% efficiency

 

[ba-brewer]

Did you add something that looks like minute rice or something that looked kind of papery?

Rice hulls helps to prevent stuck sparges, but if the grain is crushed properly you should not have to add it unless you are using a high percentage of hull-les grains like wheat, rye, corn or rice.

Flaked rice is like minute rice and can make your mash sticky.

Flaked rice adds gravity rice hulls do not.

 

[kh54s10]

Yes flaked rice is an ingredient for the recipe. It is rice hulls that aid in draining the mash tun.

If you fly sparge, you need to make sure you stir the wort really well before taking your gravity readings. If you don't the higher gravity is going to stay on the bottom and thinner low gravity wort will be on top.

Are you milling your own grain. If you don't and get your malt milled somewhere different each time, you will constantly be chasing efficiency.

I too would try batch sparging. There is a lot less to create variables.

 

[mongoose33]

I didnt do anything with the flaked rice differently, as the half pound was just supposed to help with sparge.

Rice hulls, which are just the outside of rough rice, will help with the sparge, but have no starch or sugar. The rice we'd use as an adjunct isn't that.

Admittedly, I dont measure my waters quality or PH, just use tap and hope for the best usually.

You may want to look into that. If your water is very hard/alkaline, and you use a light-colored malt bill, it's not likely to come down to the pH range we want (5.2-5.6, though there is some disagreement on that). If your water is very soft (naturally soft), then a light grain bill may work fine.

Further, you don't want to use softened water, i.e., from a home water softening system. I'm not saying your water is bad--some people are able to brew very well using their unadjusted tap water. Others--like me--can't do that unless we're brewing a dark beer using dark malts, whose natural acidity after kilning makes them more acidic, and which can then offset much or all of the alkalinity in the water.

This is one of those places, as you move forward to better and better beer, that you'll want to look into.

I crush my grain at the LHBS until I can buy my own mill.

It's pretty common that the mill at a LHBS is set very coarse; LHBS owners will say this is to avoid a stuck sparge, but it also coincidentally means you need to buy more grain. If you can, crush the grain twice at minimum. If you grab a scant handful of it after double-crushing and you can still see intact kernels, that means you're losing efficiency.

You're headed in the right direction. When the time comes for a mill, look at the Cereal Killer. My suggestion would be to avoid the Barley Crusher. And if you're made of money, get a Monster Mill and motorize it.

Here are the things that allowed me to move from so-so beer to excellent beer: controlling fermentation temps, getting the water right, controlling my own crush.

Still not sure what could have gone wring, unless it really was the crush. Cant imagine .5lbs of rice would congeal the mash, and the temp and longer mash should have resulted in a higher than normal gravity reading.

I'm still thinking crush, but water still could have something to do with it. Keep at it!

 

[Dland]

Hope it is OK to borrow this, instead of new thread, but my efficiency varies a lot too. Usually I have some idea why, like a lot of adjuncts(rye, corn) making sticky mash, or fast lazy sparge.

Today I got great efficiency form my fly sparge. I ran it slow and hot, and had a nice clean, moderate grain bill, so not a real mystery. I got 1.064 out of a mash beersmith estimated would be 1.058.

One thing that has me scratching my head is that the final runnings gravity was close to 1.040, the highest I've ever had.

 

[doug293cz]

Lots of good advice here already, so I'm going to get a little geeky and try to tie it together and explain why the advice is good advice.

Mash efficiency is defined as conversion efficiency times lauter efficiency. Brewhouse efficiency is mash efficiency times vol in fermenter / post boil volume. The ratio of mash efficiency to brewhouse efficiency is almost completely controlled by your equipment profile, and doesn't vary much with the mash and lauter process.

Conversion efficiency is the amount of sugar actually created in the mash divided by the max potential sugar in the grain bill (both measured by weight.) Turns out that the max potential sugar doesn't really vary too greatly based on the composition of the grain bill. Most base malts have about 80% potential sugar by weight (1 lb of grain converts to a max of 0.8 lb of sugar.) If your specialty grains make up 10% of your grain bill, and have 10% lower potential than your base grain, then the potential of your overall grain bill is only 1% less than if it was all base grain. Thus when looking at max potential, little error is made by ignoring the lower potential of the specialty grains (unless you have an awful lot of them.)

It turns out that the max SG of the wort in a mash (prior to any dilution) is just a function of the mash thickness (qt strike water / lb of grain.) Thus you can determine the completeness of conversion in your mash by knowing the mash thickness, and measuring the SG of the wort. You can then choose to extend the mash until you get the level of conversion you desire. In a well conducted mash you can get 95% - 100% conversion efficiency.

As has been said, the number one variable controlling the rate of conversion is the crush size. Finer grits just convert faster. The larger the grits, more more unconverted starch you are likely to have at the end of any given mash time. The next two most important variables are temperature and time. Conversion happens slower at lower temps, and longer mash times give more time for conversion to complete. A distant forth is mash pH, which has a small effect on conversion rate.

Another thing that my have affected one or more of your brews is higher gelatinization temps for recent European grown grains (weather related.) Before the starch can be converted to sugar, it must be gelatinized, and this occurs faster at higher temps. If the grain itself comes in with a higher than normal gelatinization temp, a low temp mash may end up getting very poor conversion efficiency.

Lauter efficiency is defined as the ratio of sugar collected in the BK to the sugar created in the mash (again measured by weight.) The more sugar you leave behind in your mash, the lower your lauter efficiency. A no sparge process provides the lowest lauter efficiency, followed by a single batch sparge, then a double batch sparge, triple batch sparge, etc. A well conducted fly sparge can have a lauter efficiency slightly better than a triple batch sparge. However, a poorly conducted fly sparge can have a lower lauter efficiency than a single batch sparge. It's much simpler to conduct a good batch sparge than a good fly sparge, which is why fly sparging tends to have more variability than batch sparging, and why you got recommendations to try fly sparging to help diagnose where your efficiency losses originate.

Turns out that it is relatively straight forward to predict lauter efficiency for batch sparging, but almost impossible for fly sparging. The following chart shows the max lauter efficiency possible for no sparge and 1, 2 and 3 batch sparges as a function of grain weight to pre-boil volume ratio for two different grain absorption rates (0.12 gal/lb - typical for an MLT, and 0.06 gal/lb - typical for aggressively squeezed BIAB.) Based on data provided to me by another HBT member, a good fly sparge can give you 2 - 3 percentage point higher lauter efficiency than a triple batch sparge @ 0.12 gal/lb absorption (the solid green line.)

To understand where your mash efficiency is falling short, you need to know both your conversion efficiency and your lauter efficiency. Conversion efficiency is determined by the method here. Lauter efficiency is calculated as: Mash efficiency / Conversion efficiency. If your conversion efficiency is less than 95%, then you need to look at crush, mash time, mash temp, and mash pH (in that order) to improve it. If your lauter efficiency is less than the solid line on the chart for your process, or less than the solid green for fly sparge, then you need to look into your sparge process to improve your mash efficiency. If your fly sparge lauter efficiency is lower than the solid orage line, then you would be better off doing a batch sparge.

Brew on

 

[Dland]

I was wondering about the effect of very slow gravity sparge vs pumped sparge on my particular system. The way it is set up now, the HLT is higher than MT, and can feed it for sparge by gravity only. The MT is on same level as BK, so I can gravity sparge until the BK and MT levels start getting close.

It seems to me, and this may only be my imagination, that I get better extraction from fly sparge when pump is on between MT and BK during sparge, even if constricted to the point it is about the same speed as gravity feed. Wondering if the pulling from below might help reduce channeling vs just being driven by pressure above.

 

[Transamguy77]

I would try a batch sparge on your next brew, if it’s the crush you will still have terrible efficiency and if it goes up then you know it’s something in your process and not the crush.

If it is the crush and you don’t want to spend a lot on a mill you could get a corona mill, they are fairly inexpensive, I’ve got one and have put hundreds of pounds through it and i get high 80% sometimes low 90% efficiency.

Figuring out a new system can be frustrating but once you get it dialed in you’ll be good.

 

[Dland]

Well sparge fans, I ran the same mash as last week and tried a 3 batch sparge instead of fly sparge. It did save a little time, but required a bit more fussing with disconnects and stuff, and gravity came in .006 points less gravity. So back to fly sparging for me & my current rig.

The fly sparge came in a little higher than predicted by Beersmith, and the batch sparge came in little lower, but still OK.

 

[augiedoggy]

I was wondering about the effect of very slow gravity sparge vs pumped sparge on my particular system. The way it is set up now, the HLT is higher than MT, and can feed it for sparge by gravity only. The MT is on same level as BK, so I can gravity sparge until the BK and MT levels start getting close.

It seems to me, and this may only be my imagination, that I get better extraction from fly sparge when pump is on between MT and BK during sparge, even if constricted to the point it is about the same speed as gravity feed. Wondering if the pulling from below might help reduce channeling vs just being driven by pressure above.

opposite.. pulling will normally increase the likelyhood of channeling the harder you pull the more likely the channeling is occurring.