Not sure if fly sparging correctly

[Gavin C]

How would dead space in the mash tun effect efficiency ?

Sugars are trapped in the dead-space and never leave the tun. Anytime you are losing sugars your efficiency is reduced. Specifically it reduces lautering efficiency, one facet of mash efficiency.

 

[Gavin C]

I'm not sure grain crush would improve efficiency

There's something bigger, like maybe water/grain ratio or something else to do with the mash.

?

The biggest factors in mash efficiency are crush quality and mash consistency.

Crush finer, mash thinner. This is the mantra.

It works.

 

[doug293cz]

Just want to revive this again as I've brewed today and it seemed to go well. I set up a bleeder valve on my pump and it ran really well. Thank you douglasbarbin for pointing me in the right direction.

Got my old sparge arm working as well. Sparged really slowly but want to know whether my numbers make sense. A full brew report can be found on brewtoad:https://www.brewtoad.com/recipes/archduke-franz-ferdinhandz but to cut it short:

7.4 kg maris otter
0.6kg light caramalt
0.6kg candi sugar.

Mash 1 hour
Boil 1 hour

30 litres pre boil, 25 post.

OG: 1.077.

It's the highest gravity I've had since I got my new kit but does the efficiency sound alright or am I still having issues?

Thanks.

Looked at your brew log on BrewToad and have some questions (for which I found no answers on BrewToad):

• What is "Volume of Combined Runnings" and why is it different from pre-bol volume?
• What is the definition of "Pre-Extract Gravity" and how is it different from pre-boil SG?
• Is "Post-Extract Gravity" the same as pre-boil SG? If not, what is it?

Some questions about data not in the brew log:

• What was your strike water volume?
• What was the total volume of water you used?
• Did you take a first runnings gravity (after vorlauf), and an end of runnings gravity?

Finally, pre-boil gravity -1 times pre-boil volume should equal post-boil gravity -1 times post-boil volumw. In your case this does appear to hold:

Pre-boil: 0.069 * 30 L = 2.07
Post-boil: 0.077 * 25 L = 1.925​

Since these results aren't equal it indicates an error in one or more of the measurements involved (or the volumes and/or SG's weren't properly corrected for tempurature.)

Brew on

 

[jceg316]

In the UK homebrewers don't seem too bothered by crushing their own malts, it's far more common just to buy ready crushed grain. In terms of freshness I vacuum pack the grains into smaller bags, plus I'm not sure I could do a better job. My mash tun is very wide which helps prevents stuck mashes though, so it does give me some room to experiment without ruining many batches along the way.

Which brings me onto dead space: my mash tun is 50 litres, but I only ever do up to 25 litre batches (in the fermenter) so I'm never filling it up. The false bottom is probably 1.5 inches off the bottom creating quite a big area where grain and water don't mix. However I use a pump to recirculate the wort to get round this (soon will incorporate a HERMS system). The drain tap is on the side as low as it can go so I don't think I'm losing too much, but can put a plastic tube on there to trail along the bottom and pick up as much as possible.

Doug293cz, combined runnings are all runnings from sparge/lautering combined, not sure what the difference is from preboiled runnings. Pre extract gravity is just the grain juice SG, whereas pre boil SG will include any sugars or adjuncts added once the wort is in the kettle. Not sure what post extract gravity is?

My strike water vol was 23 litres. I filled my kettle up ~25 litres as I go by 3litres per kg of grain. I mashed in until the mix looked the right consistency which was about 1 litre less than I calculated. I used about 15 litres of sparge water, meaning my total water use is 40 litres. I didn't take a first runnings gravity check.

Interesting that there is a reading error. It would make life simpler if it was a reading error. I took both readings at 25 and used brewers friend calculator to adjust for 20c.

 

[doug293cz]

...My mash tun is very wide which helps prevents stuck mashes though...

Your shallow grain bed may be contributing to your low efficiency (specifically lower lauter efficiency.) With your configuration, you might do better with batch sparging.

Which brings me onto dead space: my mash tun is 50 litres, but I only ever do up to 25 litre batches (in the fermenter) so I'm never filling it up. The false bottom is probably 1.5 inches off the bottom creating quite a big area where grain and water don't mix. However I use a pump to recirculate the wort to get round this (soon will incorporate a HERMS system). The drain tap is on the side as low as it can go so I don't think I'm losing too much, but can put a plastic tube on there to trail along the bottom and pick up as much as possible.

Recirc should help a little with your saccharification rate, and get the dead volume wort involved in the mash process (as you mention.) If you try batch sparging, be sure to recirc for a few minutes to get the sparged wort to a uniform SG.

One of the best dip tube arrangements is just a 90˚ elbow from the drain, with the end sitting about 3mm above the bottom of the MLT. This will capture more wort than a tube lying flat on the bottom. (The tube will start sucking air and break the siphon with more volume left than will the elbow.)

Doug293cz, combined runnings are all runnings from sparge/lautering combined, not sure what the difference is from preboiled runnings. Pre extract gravity is just the grain juice SG, whereas pre boil SG will include any sugars or adjuncts added once the wort is in the kettle. Not sure what post extract gravity is?

I would think the combined runnings and pre-boil volumes should be equal, unless you discard some wort or add kettle top off water. In your brew log on BrewToad, your combined runnings are 33 L and your pre-boil is 30 L. What happened to the 3 L?

Let's assume post-extract gravity is equivalent to pre-boil gravity (i.e. after addition of any sugar to the kettle.) In your case your pre-extract and post-extract gravities are the same. They shouldn't be since you added 0.6 Kg of candi sugar.

My strike water vol was 23 litres. I filled my kettle up ~25 litres as I go by 3litres per kg of grain. I mashed in until the mix looked the right consistency which was about 1 litre less than I calculated. I used about 15 litres of sparge water, meaning my total water use is 40 litres. I didn't take a first runnings gravity check.

You used 40 L of water, and collected 30 L of pre-boil wort, so you lost 10 L to grain absorption and undrainable MLT volume. Typical grain absorption is about 1 L/Kg, so 8 L for grain absorption and 2 L wort left in the bottom of the MLT. Recovering more of that 2 L of wort will help your efficiency.

First runnings gravity measurements (or just SG of a wort sample from the MLT at end of mash) are useful for determining conversion efficiency in the mash. If you know your mash efficiency and conversion efficiency, then you can calculate your lauter efficiency. When diagnosing efficiency issues, knowing whether the problem is conversion or lauter helps guide you on what needs to be improved. I discuss this in posts here, here, and here.

Interesting that there is a reading error. It would make life simpler if it was a reading error. I took both readings at 25 and used brewers friend calculator to adjust for 20c.

Sounds like a gravity reading error is less likely, which indicates that one or both of pre-boil or post-boil volume measurements is in error. Even adjusting your pre-boil volume from boiling to room temp doesn't make things come out correctly.

 

[jceg316]

Recirc should help a little with your saccharification rate, and get the dead volume wort involved in the mash process (as you mention.) If you try batch sparging, be sure to recirc for a few minutes to get the sparged wort to a uniform SG.

One of the best dip tube arrangements is just a 90˚ elbow from the drain, with the end sitting about 3mm above the bottom of the MLT. This will capture more wort than a tube lying flat on the bottom. (The tube will start sucking air and break the siphon with more volume left than will the elbow.)

The tap is so far down I can't fit a 90* elbow.

I would think the combined runnings and pre-boil volumes should be equal, unless you discard some wort or add kettle top off water. In your brew log on BrewToad, your combined runnings are 33 L and your pre-boil is 30 L. What happened to the 3 L?

Let's assume post-extract gravity is equivalent to pre-boil gravity (i.e. after addition of any sugar to the kettle.) In your case your pre-extract and post-extract gravities are the same. They shouldn't be since you added 0.6 Kg of candi sugar.

I poured 30litres into the kettle but had some wort left over. As it was not needed I threw it out. These were the very last runnings from the mash tun so should have been more water than wort. Pre extract and post are the same because I realised what they were after I added the sugar, but haven't got round to deleting the post extract gravity yet. These would have been different though.

And for my next brew I will measure at the different stages to help see where the shortfall is coming from. Thanks for those links I'll read through those threads.

You used 40 L of water, and collected 30 L of pre-boil wort, so you lost 10 L to grain absorption and undrainable MLT volume. Typical grain absorption is about 1 L/Kg, so 8 L for grain absorption and 2 L wort left in the bottom of the MLT. Recovering more of that 2 L of wort will help your efficiency.

How do you get more wort out of the grain? if it's absorbed then it's absorbed and squeezing the grain is not recommended.

Sounds like a gravity reading error is less likely, which indicates that one or both of pre-boil or post-boil volume measurements is in error. Even adjusting your pre-boil volume from boiling to room temp doesn't make things come out correctly.

I don't quite understand what you mean here sorry.

 

[doug293cz]

The tap is so far down I can't fit a 90* elbow.

Understand. If you're dumping 3 L of excess wort anyway, then it doesn't mater. But, since it's that close to the bottom, tilting the MLT could help capture what is trapped, if you need it to make volume.

I poured 30litres into the kettle but had some wort left over. As it was not needed I threw it out. These were the very last runnings from the mash tun so should have been more water than wort.

You had 30 L of wort pre-boil, and assuming the pre-boil volume was measured at 170˚F, the equivalent room temp volume would be (approximately):

30 L *(1 - 0.04 * (170 - 68) / (212 -68)) = 29.1 L​

You had 29.1 L of wort pre-boil @ 1.069 SG, and 1.069 SG is 16.826˚Plato, which means your pre-boil wort was 16.826% sugar by weight. So, the total sugar in your pre-boil wort is:

29.1 L* 1.069 kg/L * 16.826 / 100 = 5.234 kg​

0.5 kg of that was from the candi sugar, so your sugar from grain is:

5.234 kg - 0.5 kg = 4.734 kg​

Your grain bill had a potential for extracted sugar of 6.31 kg, thus your mash efficiency was:

4.734 kg / 6.31 kg = 0.750 => 75.0%​

You also left:

6.31 kg - 4.734 kg = 1.576 kg​

of sugar behind in the mash and discarded wort.

How do you get more wort out of the grain? if it's absorbed then it's absorbed and squeezing the grain is not recommended.

Squeezing is not the problem it's made out to be. If your mash and sparge pH are where they belong, then squeezing will not extract tannins. Many BIAB'ers squeeze the grain bags to get more wort out of the grain, and so does at least one sizable commercial brewery (https://alaskanbeer.com/beerpoweredbeer/.) Squeezing in a traditional MLT arrangement is difficult, but some brewers line their MLT with a BIAB bag. Makes MLT cleanup easier, but you can also lift up the bag and squeeze it if you want.

I don't quite understand what you mean here sorry.

We saw above that 29.1 L (30 L before cooling) @ 1.069 SG contains 5.234 kg of sugar. At the end of boil, you had 25 L @ 1.077 SG. 1.077 SG is 18.652˚Plato, so you had:

25 L * 1.077 kg/L * 18.652 / 100 = 5.022 kg​

of sugar post-boil. Since sugar does not evaporate during the boil, there is an apparent unaccounted sugar loss of 0.212 kg. If both of the SG measurements are correct, then one (or both) of the volume measurements has to be incorrect, unless the 25 L is a "to fermenter" volume with some trub (and wort) left in the BK.

Brew on

 

[jceg316]

Understand. If you're dumping 3 L of excess wort anyway, then it doesn't mater. But, since it's that close to the bottom, tilting the MLT could help capture what is trapped, if you need it to make volume.



You had 30 L of wort pre-boil, and assuming the pre-boil volume was measured at 170˚F, the equivalent room temp volume would be (approximately):

30 L *(1 - 0.04 * (170 - 68) / (212 -68)) = 29.1 L​

You had 29.1 L of wort pre-boil @ 1.069 SG, and 1.069 SG is 16.826˚Plato, which means your pre-boil wort was 16.826% sugar by weight. So, the total sugar in your pre-boil wort is:

29.1 L* 1.069 kg/L * 16.826 / 100 = 5.234 kg​

0.5 kg of that was from the candi sugar, so your sugar from grain is:

5.234 kg - 0.5 kg = 4.734 kg​

Your grain bill had a potential for extracted sugar of 6.31 kg, thus your mash efficiency was:

4.734 kg / 6.31 kg = 0.750 => 75.0%​

You also left:

6.31 kg - 4.734 kg = 1.576 kg​

of sugar behind in the mash and discarded wort.


Squeezing is not the problem it's made out to be. If your mash and sparge pH are where they belong, then squeezing will not extract tannins. Many BIAB'ers squeeze the grain bags to get more wort out of the grain, and so does at least one sizable commercial brewery (https://alaskanbeer.com/beerpoweredbeer/.) Squeezing in a traditional MLT arrangement is difficult, but some brewers line their MLT with a BIAB bag. Makes MLT cleanup easier, but you can also lift up the bag and squeeze it if you want.


We saw above that 29.1 L (30 L before cooling) @ 1.069 SG contains 5.234 kg of sugar. At the end of boil, you had 25 L @ 1.077 SG. 1.077 SG is 18.652˚Plato, so you had:

25 L * 1.077 kg/L * 18.652 / 100 = 5.022 kg​

of sugar post-boil. Since sugar does not evaporate during the boil, there is an apparent unaccounted sugar loss of 0.212 kg. If both of the SG measurements are correct, then one (or both) of the volume measurements has to be incorrect, unless the 25 L is a "to fermenter" volume with some trub (and wort) left in the BK.

Brew on

Thanks for your help on this. If we ever meet I'm buying you a beer!

So 75% efficiency isn't too bad, that's about average and better than I thought I was getting. But some of those numbers aren't quite correct. I would have measured pre-boil volume at about 60C, which is 140F. Also I did have 33 litres pre boil, I just threw out the last 3 litres, or does that not matter in this equation?

Candi sugar would have been 0.6kg.

Next time I brew I'm gonna record gravity readings at all available stages. Also gonna get some litmus paper/iodine solution to check pH of wort, probably something I should have done a long time ago..

Whilst I'd like my hydrometer readings to be wrong and really all numbers are what they should, I think it's far more likely volume readings are off. I use fermenting buckets to measure large quantities of liquid, so as long as the volume is a denomination of 5 I'm golden. Gonna add a large measuring jug to the shopping list.

 

[doug293cz]

Thanks for your help on this. If we ever meet I'm buying you a beer!

You are welcome. I enjoy helping people understand how things work, because I like knowing how things work.

So 75% efficiency isn't too bad, that's about average and better than I thought I was getting. But some of those numbers aren't quite correct. I would have measured pre-boil volume at about 60C, which is 140F. Also I did have 33 litres pre boil, I just threw out the last 3 litres, or does that not matter in this equation?

The pre-boil volume measurement at 140˚F would change the RT corrected volume from the 29.1 L I used to 29.4 L. That will increase the difference between pre-boil sugar and post-boil sugar.

Mash efficiency is defined as the percentage of potential sugar in the grain that makes it into the brew kettle. So, since those 3 L didn't make it into the BK, they are treated as a lautering loss, just as wort left in the bottom of the MTL and the wort absorbed by the grain. Had you put those 3 L into the BK, and boiled off the excess water, your mash efficiency (and OG) would have been a little higher.

Candi sugar would have been 0.6kg.

Candi sugar does not raise the SG as much a sucrose (which is the SG standard against which all other sugars are measured.) If you look at the PPG column for your recipe on BrewToad, you will see that it is 38 PPG. Sucrose is 46 PPG. So, that's why I used a lower number in the calculation.

0.6 kg * 38 PPG / 46 PPG = 0.4956 kg, which I rounded to 0.5 kg​

So, 0.6 kg of candi sugar has the same SG effect as 0.5 kg of sucrose. All of the other calculations are also based on equivalent weights of sucrose, as that's the way all brewing calculations are done.

Whilst I'd like my hydrometer readings to be wrong and really all numbers are what they should, I think it's far more likely volume readings are off. I use fermenting buckets to measure large quantities of liquid, so as long as the volume is a denomination of 5 I'm golden. Gonna add a large measuring jug to the shopping list.

I agree that volume readings are most likely to be inaccurate. Fermenting buckets make lousy measuring buckets, unless you have carefully calibrated them. Any volume markings molded into the buckets are usually inaccurate. You will also need to check the calibration of any measuring jug you buy. I bought a graduated 1 gal pitcher to use to calibrate my other volume measurements, and recently found out that its markings are not accurate. Now I have to recalibrate everything.

Brew on

 

[Gavin C]

Really like reading your maths @doug293cz

 

[doug293cz]

Really like reading your maths @doug293cz

Thanks. I do it because I found that learning the math helped me understand how the different steps of the process interact, and pinpoint where issues may be originating. Hopefully, the examples will help others gain the same understanding, and maybe motivate them to dig deeper into the inner workings of brewing. The more you understand about how things work, the better you can control them.

Brew on

 

[Gavin C]

Thanks. I do it because I found that learning the math helped me understand how the different steps of the process interact, and pinpoint where issues may be originating. Hopefully, the examples will help others gain the same understanding, and maybe motivate them to dig deeper into the inner workings of brewing. The more you understand about how things work, the better you can control them.

Brew on

I couldn't agree more. Very well put.

 

[jceg316]

Definitely agree with you too on learning the necessary equations. The more I get into brewing the more I realise it's the small detail which makes the biggest differences.

I use Excel a lot at work so it's pretty easy for me to put these numbers into excel so in the future I can input my readings and I get an answer in the cell next to it. I'll probably do that from now on anyway to properly measure the efficiency of my kit and work out where the weakest step is. I'm brewing again in 2 weeks, I have some pilsner malt and a few hop varieties I've never used before which I'm excited about, but will make notes along the way.

Thanks for your help on this! I'll probably post again with more stages from brewday.