Problems with my mash tun

[norbyd]

I run a converted 10 gallon igloo cooler for my mash tun with another one for my lauter tun. Lately I have been noticing that I am somehow losing water during my mash. The only potential problems I can think of are that either my mash tun is leaking, the grain is somehow absorbing way more water than expected, or a bunch of water is evaporating out of my mash tun (though there is a lid on it)

From my last batch:
5.9 lbs of grain
Mashed for an hour with 1.85 gallons of water
Sparged with an additional 2.6 gallons of water
I estimated the grain would absorb .7 gallons of water
I estimated that I should have had 3.75 gallons of wort in my kettle
I ended up with 2.75 gallons of wort in my kettle

Has anybody run into anything like this? I recently started going to a new brew supply shop, and I've been thinking that their mill is milling the grains to finely, but I wouldn't think it would have that dramatic of an effect on the absorption level.

 

[ruger988]

I run a converted 10 gallon igloo cooler for my mash tun with another one for my lauter tun. Lately I have been noticing that I am somehow losing water during my mash. The only potential problems I can think of are that either my mash tun is leaking, the grain is somehow absorbing way more water than expected, or a bunch of water is evaporating out of my mash tun (though there is a lid on it)

From my last batch:
5.9 lbs of grain
Mashed for an hour with 1.85 gallons of water
Sparged with an additional 2.6 gallons of water
I estimated the grain would absorb .7 gallons of water
I estimated that I should have had 3.75 gallons of wort in my kettle
I ended up with 2.75 gallons of wort in my kettle

Has anybody run into anything like this? I recently started going to a new brew supply shop, and I've been thinking that their mill is milling the grains to finely, but I wouldn't think it would have that dramatic of an effect on the absorption level.

Does seem like quite a bit of absorption, I've never done a mash anywhere near that small, maybe a factor of the size of the mash? I assume you'd notice if there were a puddle under/around your MLT. What's your efficiency like? I HIGHLY doubt you're losing that much to evaporation, even without a lid... thats boil off rates (~1g/hr)

Side note... how well do you maintain temps over an hour with that small of a mash in a 10g cooler?

 

[Gavin C]

What have you measured the mash tun dead space to be?

Evaporation is not happening

Double the typical grain absorption is not happening.

You either

• have ~1gallon of mash tun deadspace
• Are milling so fine as to be creating severe lautering issues
• have incorrect volumetric calculation going into your HLT and/or on the output in your BK

That's a very big MT for such a tiny grain-bill.

 

[Magnus314]

Deadspace. It doesn't change (much) by batch size.

 

[norbyd]

This most recent batch was just a 3 gallon batch. I normally do 5.5 gal batches. But I have noticed the loss of water/wort in my 5.5 gallon batches as well.

I use the mesh from around a hot water pipe for my MT filter, so my deadspace is almost zero.

Ruger: my efficency is usually around 70%, my MT holds temp really well. I rarely see a change in temp in the hour of mashing.

 

[norbyd]

Here are the numbers from my most recent 5.5 gallon brew:
10 lbs of grain
Mashed with 3.125 gal of water
Sparged with an additional 5.07 gal of water
Expected absorption was 1.2 gal
Expected wort in kettle was 7 gal
I ended up with 6.25 gal in my kettle

 

[ruger988]

Post a picture of your crush, sounds like Gavin may be onto something with milling too fine and having lautering issues.

What are you using to measure volumes?

 

[Picker]

Is it possible liquid could be seeping into the space between the cooler inner and outer shell?

 

[Stillraining]

Weigh your spent grains next time to verify absorption. If its not there then you made a mistake in water additions. Or your boil kettle is marked wrong.

( Like has been mentioned a leak you would see/notice as above as added weight to your tun and its not evaporation)

 

[norbyd]

Next time I brew I will take a picture of the grains, I'm pretty sure the mill at the new place I've been going to is too fine.

My Mash and Lauter tuns have marks on the inside that measure up to 10 gallons, in my kettle I use a measuring stick. The stick may not be spot-on accurate but there is no way it would be off by that much

Is it possible liquid could be seeping into the space between the cooler inner and outer shell?

I thought about that too, I can't think of any good way to check that without tearing my mash tun apart though

 

[ruger988]

Next time I brew I will take a picture of the grains, I'm pretty sure the mill at the new place I've been going to is too fine.

My Mash and Lauter tuns have marks on the inside that measure up to 10 gallons, in my kettle I use a measuring stick. The stick may not be spot-on accurate but there is no way it would be off by that much



I thought about that too, I can't think of any good way to check that without tearing my mash tun apart though

I'd hope you'd notice your MT weighing an extra ~8lbs if it had absorbed a gallon of wort.

 

[norbyd]

I'd hope you'd notice your MT weighing an extra ~8lbs if it had absorbed a gallon of wort.

Haha yeah that should be pretty noticeable.

I think the next time I brew I'm just gonna weigh everything out before and after I mash and see if everything matches up.

 

[Gavin C]

Weigh your spent grains next time to verify absorption.

Not an easy thing to calculate.

Initial mass of grain - starches/sugars given up to wort + wort absorbed = final mass.

The lost starches sugars need to be known if mass of wort absorbed is to be calculated.


There is no need as it is very easy to find the volume of water in the tun assuming all measures of volume in and out are known.

 

[Stillraining]

Not an easy thing to calculate.

Initial mass of grain - starches/sugars given up to wort + wort absorbed = final mass.

The lost starches sugars need to be known if mass of wort absorbed is to be calculated.


There is no need as it is very easy to find the volume of water in the tun assuming all measures of volume in and out are known.

Well since he is at a loss as to where the water is going and says he has a handle on his volumes ( yet to be proven) its a good start..and not that hard to calculate actually..Final SG from 100% potential will give us that weight ....there will definitely not be 8 lbs of available sugar but their could be various amounts above standard absorption values of water yet to be extracted up to and including 8 lbs or the actual amount hes missing what ever that really is...like I said "if" any as im still not convinced of that.

Iv never been off on my volumes so something isnt adding up.

 

[Gavin C]

Well since he is at a loss as to where the water is going and says he has a handle on his volumes ( yet to be proven) its a good start..and not that hard to calculate actually..Final SG from 100% potential will give us that weight ....there will definitely not be 8 lbs of available sugar but their could be various amounts above standard absorption values of water yet to be extracted up to and including 8 lbs or the actual amount hes missing what ever that really is...like I said "if" any as im still not convinced of that.

Iv never been off on my volumes so something isnt adding up.

My point is that the weight of the wet grain after the mash can be similar or even less than the dry weight before the mash. It's not a useful thing to know.

Volume is a lot easier to measure. It's the volume at issue. Just measure that is all I was trying to say.

Weighing wet grain and trying to calculate absorbed volume involves more work, is less accurate and requires more math. Just seems pointless to me

 

[Stillraining]

My point is that the weight of the wet grain after the mash can be similar or even less than the dry weight before the mash. It's not a useful thing to know.

Volume is a lot easier to measure. It's the volume at issue. Just measure that is all I was trying to say.

Weighing wet grain and trying to calculate absorbed volume involves more work, is less accurate and requires more math. Just seems pointless to me

I think you missed the point of his whole thread...he has no more measurable liquid according to him left in his tun... So that leaves 4 options. its ether hiding in the mash ( Unlikely ) evaporated (more unlikely} or leaked out somewhere..(possibly likely.).or didn't get added in the first place...(most likely).

Eliminating the possibility of it hiding in the mash or the tun is all I'm trying to do for him....he could squeezes the crap out of it as well but that's less accurate.

Setting his mash tun on a scale before and after mashing is very simple do do...I don't know what is simpler. If we were trying to find a pint I would agree with you but this is 8 pounds.

 

[norbyd]

Yeah I know the weight won't match up exactly, but I'm trying to see if they are close. Right now I'm leaning towards the possibility that somehow the wort is leaking in between the lining of the mash tun. It is possible that I am screwing up the initial volumes, but I feel pretty confident that I am not making that mistake and would surprised if that were the case, but who knows.

I don't plan on brewing for about a week (gotta wait for carboy space to clear up), but I'll keep a close eye on the entire mashing process and let you know what happens. Thanks for the input!

 

[The_Bishop]

How much soupy wet grain is in the bottom of your mash tun? Having a braid doesn't mean '0' deadspace. Unless the drain is dead nuts on the bottom of the mash tun, you'll have dead space. Wort/water will not flow 'uphill' into the braid.

 

[PeteNMA]

WHy not just put some hot water into the tun, leave it for an hour and see if any has gone missing?

 

[CA_Mouse]

Here are the numbers from my most recent 5.5 gallon brew:
10 lbs of grain
Mashed with 3.125 gal of water
Sparged with an additional 5.07 gal of water
Expected absorption was 1.2 gal
Expected wort in kettle was 7 gal
I ended up with 6.25 gal in my kettle

My calculations show that you should have mashed with 3.92 gallons of water and sparged with 5.97 gallons. Collecting 7.095 gallons of wort pre-boil. That is mashing with 1.250 quarts of water/pound of grain. 1.2 gallons of grain absorption plus 0.8 gallons of tun dead space (typical for 10 gallon round cooler) is 2 gallons of loss.

Strike Water 3.125 gallons
Grain Absorption 1.2 gallons
Tun Dead Space 0.8 gallons
First runnings 1.125 gallons
Sparge Water 5.97 gallons
Total Wort collected should have been 7.095 gallons

It looks like you are mashing at too low of a ratio and then sparging with too low of a volume.

 

[ruger988]

Simple test to see if you're issue is your volume measurements would be to measure your collected wort the same way you measure your mash/sparge water. Then even if you're wrong, you're wrong consistently.

 

[Gavin C]

My calculations show that you should have mashed with 3.92 gallons of water and sparged with 5.97 gallons. Collecting 7.89 gallons of wort pre-boil. That is mashing with 1.250 quarts of water/pound of grain. 1.2 gallons of grain absorption plus 0.8 gallons of tun dead space (typical for 10 gallon round cooler) is 2 gallons of loss.

Strike Water 3.125 gallons
Grain Absorption 1.2 gallons
Tun Dead Space 0.8 gallons
First runnings 1.125 gallons
Sparge Water 5.97 gallons
Total Wort collected should have been 7.095 gallons

It looks like you are mashing at too low of a ratio and then sparging with too low of a volume.

Nice job Mouse

Numbers rarely if ever lie

They speak to what I earlier tried, so crudely, to infer.

Thick mash and inadequate batch sparge volume coupled with an UNTIPPED TUN deadspace give the results the OP is seeing.

Usually comes back to

• Mash thinner
• Sparge correctly (if you sparge)

 

[swander]

His results are pretty much as expected. The water was absorbed by the grain.
A quart per pound of grain absorption is on the very low side. He is losing about 1.15 quarts/lb and that is very reasonable. See: https://www.homebrewtalk.com/showthread.php?t=52012 or Google "grain absorption constant".

The expectation to lose only .7 gallons was flawed.

Weigh the spent grain and you will find your water at ~8.3 lbs / gallon.

 

[Gavin C]

His results are pretty much as expected. The water was absorbed by the grain.
A quart per pound of grain absorption is on the very low side. He is losing about 1.15 quarts/lb and that is very reasonable. See: https://www.homebrewtalk.com/showthread.php?t=52012 or Google "grain absorption constant".

The expectation to lose only .7 gallons was flawed.

Weigh the spent grain and you will find your water at ~8.3 lbs / gallon.

That is an erroneously high grain absorption.

0.1 gallons/pound is more typical.

Any higher value speaks to lautering issues. Therein lies the problem.

My system, I typically see under 0.05 gallons/pound lost to absorption

 

[swander]

That is an erroneously high grain absorption.

0.1 gallons/pound is more typical.

Any higher value speaks to lautering issues. Therein lies the problem.

My system, I typically see under 0.05 gallons/pound lost to absorption

I always brew 10G batches and 20 lbs of grain nearly fills a 7 gallon bucket when I mill it. At .05 gallons/lb, that would only be 1 gallon. It would seem that a gallon would hardly dampen that amount of grain. My spent grain is soggy.

Maybe that is a BIAB advantage, and I have to admit I have never BIAB, but that sounds incredible. I'll standby and let others comment, but I'm 90% sure my grain absorbs 4x that amount. I'll weigh spent grain next time and update (eat my words).

 

[Gavin C]

I always brew 10G batches and 20 lbs of grain nearly fills a 7 gallon bucket when I mill it. At .05 gallons/lb, that would only be 1 gallon. It would seem that a gallon would hardly dampen that amount of grain. My spent grain is soggy.

Maybe that is a BIAB advantage, and I have to admit I have never BIAB, but that sounds incredible. I'll standby and let others comment, but I'm 90% sure my grain absorbs 4x that amount. I'll weigh spent grain next time and update (eat my words).

Weighing the grain is not going to be useful. The grains lose weight o sugars/starches into the wort. The gain weight via absorption of wort. The weight of the MT at the end is

MT after brew mass= MT weight + mass of dead space wort + mass of wet grain.

Mass of dry grain- mass of starches/sugars lost to wort+ mass of absorbed wort = mass of wet grain.

You can see how pointless a calculation it becomes.

If your calculated wort absorption numbers are significantly more than 0.1gallons/lb for a conventional mash-tun you have lautering issues.

Simple as that. That is the issue here. Not an odd leaking tun, no mysterious evaporating wort.

Just a plain ol' MT with a bazooka tube with some inaccurately measured dead-space (it's not zero) and possibly lautering issues to compound the issue.

Pre-boil volume is the target after the mash. If you're short, sparge more. All the added dead-space will do is reduce efficiency for which you can explore equipment mods or increase the grain-bills accordingly.

 

[wilserbrewer]

.



Pre-boil volume is the target after the mash. If you're short, sparge more.

This! All these volume calculations taken to two decimal places is making my head hurt. IMO a simple check of pre boil volume should always be done...if short, simply sparge a bit more to proper volume.

The only thing I calculate is one simple subtraction, pre boil volume, less measured actual wort collected, equals sparge volume. I feel this should be done regardless of any calculations you have done as an actual check of your process. Mash short, sparge to PB volume, incredibly simple!

Weighing your spent grain is meaningless, as hopefully most of the weight is in your beer through conversion to soluble sugars.

 

[RM-MN]

I always brew 10G batches and 20 lbs of grain nearly fills a 7 gallon bucket when I mill it. At .05 gallons/lb, that would only be 1 gallon. It would seem that a gallon would hardly dampen that amount of grain. My spent grain is soggy.

Maybe that is a BIAB advantage, and I have to admit I have never BIAB, but that sounds incredible. I'll standby and let others comment, but I'm 90% sure my grain absorbs 4x that amount. I'll weigh spent grain next time and update (eat my words).

Yes and yes. Your grains do absorb a lot of water and won't let it go. You have to force it out but if you try that with your conventional tun you will likely collapse or break something. That is not a problem with BIAB. You can squeeze out a lot more wort that way. You should try a couple batches that way. Make sure to get your grains milled finer for it since you can't get a stuck sparge and do a smaller than your usual dunk or pour over sparge, then check your preboil gravity and compare it to your normal preboil with the conventional tun. You might get a surprise.

 

[Ozarks Mountain Brewery]

Ive found its just much easier just to keep the water 1 inch over the grain stir for about 5 minutes, measure then wait. and for the sparge to have more water than you need and sparge for the correct gravity or boil volume, no 2 brews are the same, too many variables change from brew to brew and hit exact numbers on water "unless" your brewing the same beer with the same grain bought the same day and the weather "humidity, pressure, heat" is exactly the same.

not saying its impossible just much easier

 

[doug293cz]

I always brew 10G batches and 20 lbs of grain nearly fills a 7 gallon bucket when I mill it. At .05 gallons/lb, that would only be 1 gallon. It would seem that a gallon would hardly dampen that amount of grain. My spent grain is soggy.

Maybe that is a BIAB advantage, and I have to admit I have never BIAB, but that sounds incredible. I'll standby and let others comment, but I'm 90% sure my grain absorbs 4x that amount. I'll weigh spent grain next time and update (eat my words).

To put some numbers on this, for 20 lbs of gain, 13 gal pre-boil, 11 gal post-boil, 100% conversion efficiency, 0.05 gal/lb "apparent" grain absorption, and equal volume 1st & 2nd runnings:

Sugar to BK = 14+ lbs, so less than 6 lbs of original grain wt remains in drained mash
Actual retained water = 2+ gal (0.1+ gal/lb)​

The actual retained water is more than the apparent retained water since some of the volume of wort is due to the sugar, so the volume of water in the wort is less than the volume of the wort. Thus you have ~6 lbs of the original grain mass with ~2 gal of water in the spent grain. Not nearly as dry as 20 lbs of grain with 1 gal of water.

I left out all the decimal places so @wilserbrewer 's head wouldn't hurt so much

Brew on

 

[Stillraining]

To put some numbers on this, for 20 lbs of gain, 13 gal pre-boil, 11 gal post-boil, 100% conversion efficiency, 0.05 gal/lb "apparent" grain absorption, and equal volume 1st & 2nd runnings:

Sugar to BK = 14+ lbs, so less than 6 lbs of original grain wt remains in drained mash
Actual retained water = 2+ gal (0.1+ gal/lb)​

The actual retained water is more than the apparent retained water since some of the volume of wort is due to the sugar, so the volume of water in the wort is less than the volume of the wort. Thus you have ~6 lbs of the original grain mass with ~2 gal of water in the spent grain. Not nearly as dry as 20 lbs of grain with 1 gal of water.

I left out all the decimal places so @wilserbrewer 's head wouldn't hurt so much

Brew on

Well I come up with about 7.4 lbs of extracted sugar from your example leaving 12.6 lbs of spent grains dry weight .... but I'm no math guy and we have gotten off track sort of. I will leave it to you guys and the OP to figure out.
Carry on

 

[doug293cz]

Well I come up with about 7.4 lbs of extracted sugar from your example leaving 12.6 lbs of spent grains dry weight .... but I'm no math guy and we have gotten off track sort of. I will leave it to you guys and the OP to figure out.
Carry on

How do you figure? Twenty lb of grain will contain close to 16 lb of potential extract. If you only get 7.4 lb of extract then you have a mash efficiency of less than 50%.

Brew on

 

[wilserbrewer]

Well put Doug, the water retained in 20 lbs of fresh milled grain is a lot different than the water retained in "20 lbs" of spent hulls....

I think we're past the idea of weighing the spent grain the calculations involved there would surely require Advil.

Easier to measure gravity of the wort I guess....

 

[Stillraining]

How do you figure? Twenty lb of grain will contain close to 16 lb of potential extract. If you only get 7.4 lb of extract then you have a mash efficiency of less than 50%.

Brew on

LIke I say Im no math guy...

If 2 row has a potential of conversion of .37 points per pounds, I calculated that as a part of the equation...or LBS x.37 to get 7.4

But I got D's in algebra..

 

[NatureOfTheYeast]

WHy not just put some hot water into the tun, leave it for an hour and see if any has gone missing?

For some reason this seemed to be glossed over. If you are coming up short of your volume, the first test should be to determine if your mash tun is leaking. Fill with a couple of gallons of hot water from the faucet, and wait. Easy peasy.

If your tun is water tight, then the next thing to do is calibrate your kettle and mash tun volumes together. Notch a stick at 1 gallon, 2 gallons, etc in the mash tun, then another set of marks for the kettle. Crayons are great for this, since they work while wet. Use this stick for your next brew session, and compare it to the stick you've been using. If they match up, then move on to the more complicated equations of extract, remaining moisture, etc. Occam's razor and all that...

It's also possible that grain dust from too fine of a grind is causing lauter issues, basically creating a stuck sparge with a couple of quarts remaining. You could test this by putting your hose into some kind of collection jar or pitcher and stirring the grains with your paddle after your runoff appears to be complete. If anything more than a quart comes out, I'd lean strongly towards a late-runoff stuck sparge. I had this same problem and solved it by slowly adding my grains to my LHBS's mill, rather than dumping it all into the hopper at once. Less dust, and less shredded husks. I can't explain the mechanism behind this, but it fixed my stuck sparges and is at least worth a try.

I hope you figure this out. This kind of frustration really takes the fun out of brew day, but we all have hitches like this in our system/process. Good luck getting it hammered out, and keep on brewing brother!

 

[norbyd]

For some reason this seemed to be glossed over. If you are coming up short of your volume, the first test should be to determine if your mash tun is leaking. Fill with a couple of gallons of hot water from the faucet, and wait. Easy peasy.

If your tun is water tight, then the next thing to do is calibrate your kettle and mash tun volumes together. Notch a stick at 1 gallon, 2 gallons, etc in the mash tun, then another set of marks for the kettle. Crayons are great for this, since they work while wet. Use this stick for your next brew session, and compare it to the stick you've been using. If they match up, then move on to the more complicated equations of extract, remaining moisture, etc. Occam's razor and all that...

It's also possible that grain dust from too fine of a grind is causing lauter issues, basically creating a stuck sparge with a couple of quarts remaining. You could test this by putting your hose into some kind of collection jar or pitcher and stirring the grains with your paddle after your runoff appears to be complete. If anything more than a quart comes out, I'd lean strongly towards a late-runoff stuck sparge. I had this same problem and solved it by slowly adding my grains to my LHBS's mill, rather than dumping it all into the hopper at once. Less dust, and less shredded husks. I can't explain the mechanism behind this, but it fixed my stuck sparges and is at least worth a try.

I hope you figure this out. This kind of frustration really takes the fun out of brew day, but we all have hitches like this in our system/process. Good luck getting it hammered out, and keep on brewing brother!

Yeah it looks like I just need to be ready to troubleshoot as many potential problems as possible next brew day. I treated for leaks in my MT the other day and found a minor one, but not enough to account for the loss I'm finding on brew day. I'm planning on working on my MT a little to try and eliminate any potential leaks so that shouldn't be an issue any more going forward (ideally, that is). A stuck spare at the end would make a lot of sense, I'll try to figure out of that is the issue. Worst case I would just need to use rice hulls in all of my mashes.

I didn't even think about the fact that the height of the tubing mesh would contribute to the deadspace, it makes perfect sense, but it literally just didn't cross my mind. Thanks for pointing that out, I'll make the appropriate adjustments.

I appreciate all of your guys' feedback. I'm planning on brewing this Saturday, so I should have updates by then.

 

[norbyd]

Update:

I brewed yesterday and adjusted my mash tun so the leaking, though only minimal before, was completely gone, I adjusted my levels for deadspace, and I went back to an old brew shop that I knew had their mill dialed in. I hit all my levels spot and and still met the OG I was shooting for.

Thanks for all the feedback guys!