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Mash Tun water volumes too high


New Forum Member
Mar 2, 2015
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Birmingham, AL
I am new to All Grain brewing so this is my first time using a cooler system.  I have set up a 5 gallon cooler system in Beersmith and it seemed pretty straight forward.  I have entered in 2 recipes using about 12 lbs of malt.  The recipes call for about 4 gallons of strike water.  When I tried the first recipe this weekend I ended up with too much water.  I had to drain some off as I was trying to add the grains.  By the time I added the sparge water I was at over 6 gallons in my kettle for a 5 gallon batch.  Can anyone help me figure out what I am doing wrong?  My Mash Tun settings are below.  I show zero for deadspace because my false bottom does not create very much and I don't know how to calculate that.

Volume = 5 gallons
Weight = 10 gallons
Specific heat = .3
Deadspace = 0

OK, take a deep breath and have a beer.  First, a 5-gallon cooler is pretty minimal for a 5-gallon batch size and will probably require a lower water-to-grain ratio for higher gravity brews like you seem to have here.

Now go back to your recipe and click on the 'mash' tab.  At the bottom, you should see the numbers for 'Mash Tun Volume' and if this number exceeds 5 gallons then you should have a red dot next to it if you have set up your equipment profile correctly.  This indicates that your strike water + grain volume exceeds your entered mash tun volume in your equipment profile.  If the volume is greater than 5 gallons and the dot is blue, then your equipment profile is set up for greater than whatever the calculated volume is.  When I used your numbers above my grain plus strike water was about 2 quarts above what my 5-gal cooler would handle.

You don't say if you are batch sparging or fly sparging.  If you are fly sparging, you should then sparge up to your desired pre-boil volume and then shut it off.  If you are batch sparging, check your loss to trub in your equipment profile, it may be set too high and leaving you with a lot of wort/trub left in your pot.

You should also look at your boil off rate by measuring carefully before and after boil.  You can adjust this in your equipment profile as well.

Start by checking these numbers and making any adjustments to your equipment profile that is needed.  On your next brew day, measure your volumes carefully: strike water, sparge water (if batch sparging), pre- and post- boil volumes.  Use these numbers to further tune in your equipment profile and your grain absorption (found in 'options', 'advanced') to reflect your actual numbers.

If you have more issues after that, check back and give us a snapshot of your numbers versus the predicted values and we can give you some more areas to look at.
Thanks for the reply.  I will check all of that out.  It sounds like the best thing to do is to buy 10 gallon coolers, but since I am building an all electric setup I hate to spend the money on something temporary.  I will play around with the numbers and take the measurements you suggested and see where that gets me.
I'm having a similar issue so I thought I would continue the thread.  I'm brewing a 5 gal batch of a Bell's Two Hearted clone.  13.33 lbs of grain.  Here's where I get confused.  The recipe calls for 7 gallons of water.  My Beersmith setup says I need 8.62 gal total.  I've been trying to identify where the excess is and I'm coming up empty.

Today was my brew day.  Here's a bit more information:

1.  I used Beersmith's recommendation and heated up 8.5 gallons.  I'm batch sparging.
2.  I have a 5 gal igloo mashtun.  First runnings yielded 2.25 gal of wort.
3.  Second runnings brought the total to 5 gal of wort (or added 2.75 gal).
4.  So, for the next sparge, I added the rest of the sparge water but only took enough runnings to get to 6.5 gal of wort in the boil kettle.  I dumped the rest. 
5.  Boil time today was 75 minutes.

My brewhouse efficiency was about 60% today.  A few questions:

1.  I feel like Beersmith calculated too much water but I can't find a serious excess in my setup.  Here are some numbers in my setup.  Mash tun Volume 5 gal.  Mashtun Deadspace .3 gal.  Adjust mash vol for deadspace box is checked.  I feel like that number is accurate.  Boil volume is 6.52 gal.  Boil time is 60 min.  Boil off is .8 gal.Cooling shrinkage at 4%.  Batch volume is 5.5 gal.  Fermenter loss is .5 gal.

Pre-boil gravity today was 1.040.  Pre-boil volume 6.5 gal
5.5 gal went into the fermenter.  OG 1.054

2.  I'm also trying to up my brewhouse efficiency.  It used to be 52%, so 60% is a great improvement.  I was draining my mashtun too quickly.  Today I slowed it down a lot and my numbers went up.  However, I'm still not in the 70%'s.  Today I mashed at 150 degrees, per the recipe, and sparged at 170.  The recipe said it had a target OG of 1.063, Efficiency of 65% and pre-boil volume of 6.6 gal. 

Sorry if this is an information dump.  I'm just very lost on getting Beersmith to give me the right water volume and upping my efficiency. (Also, yes, I have read the Beersmith article on upping your efficiency). 

Any thoughts would be much appreciated.  Thanks for your help in advance!   

dsoleil said:
Beersmith setup says I need 8.62 gal total. 

Using your numbers, I matched gallons total water needed. My estimated OG was 1.055. Oginme left excellent equipment and use of BeerSmith advice to the OP, so I won't be redundant about it.

I have a 5 gal igloo mashtun.  First runnings yielded 2.25 gal of wort.
Boil time is 60 min. 

Earlier in your post, you said actual boil time was 70 minutes. I used 70 and it matched your other numbers. This may indicate your evaporation rate is lower than you have it set for.

You didn't say how much wort you dumped after getting a full kettle?

When my numbers line up with yours, BeerSmith says you need more than a 5 gallon mashtun at liquor to grist ratios of more than 1:1. Does this line up with your equipment?

So, I'm suspecting three things.

1) Total water an boil volume are stated at hot temperatures in BeerSmith. If you're filling your HLT cold, you have to add expansion to that number.

2) You may need to adjust the grain absorption number. This is found in Options > Advanced. The absorption number is subject to change based on how well your malt is milled.

3) If the malt is milled by your LHBS, it may be too coarse for higher efficiency. Many stores have their gap just a little wider than optimal. This isn't anything sinister, it's just that most of their business is in extract kits which require coarser milling of specialty malts. Most all grain brewers learn to ask for their grain to be double milled if the store doesn't already do that.

Thank you so much Brewfun!  I really appreciate it.  I think you're spot on with all three of your recommendations.  I do have access to another mill from an experienced homebrewer I know.  I will give that a shot.  Yes, you are correct that Beersmith says my mashtun needs to be bigger.  And, no, I didn't measure how much extra wort I dumped.  I thought of it after that horse already left the barn.  DOH!  :eek:

As far as water volume is concerned, as a relative newbie, is there a way for me to tell in Beersmith how much cold water it recommends at the beginning of a recipe?  Or is there a way to calculate that from the hot volume total?  It makes sense now why I overshot the water total. 

Thanks again for all the help!
dsoleil said:
As far as water volume is concerned, is there a way for me to tell in Beersmith how much cold water it recommends at the beginning of a recipe?  Or is there a way to calculate that from the hot volume total?

Two ways:

Hot volume /1.04 Where the 4 represents whatever expansion factor you've chosen.


Set the expansion to zero and fill to the total volume needed. Then just turn the expansion factor back on.