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Where is my volume going?

I doughed in with 5 gal for a 12.5lb grain bill. I got exactly 3gal first running. I added 3 gallons of sparge water and wound up with 3.5gal in th fermenter. This has been an ongoing problem. I use a 42qt rectangular cooler for a mlt. Counterflow chiller with a chugger pump. Pre boil grav was 1.055 and original grav was 1.072. I don’t get where I lost 1.5gal. Target OG was 1.067.

8 gallons on the face of it sounds about right. Do you use a brewing water(volume) calculator? 60 or 90 minute boil? Depending on where you live boiloff can vary and possibly your boil could be too vigorous? Excessive equipment loss?

3.5 gallon post boil volume x 72 gravity units / 55 gravity units = 4.6 gallon pre-boil volume. Did you measure pre and post boil volume? I usually shoot for 6.67 to 6.75 gallons pre-boil for a 60 minute boil to end up around 5.5 gallon post boil volume to factor in loss of volume due to trub. Places where you may be losing volume is dead space in MLT and hoses, CFC, etc. I agree with voodoo_donut that boiling may be a bigger factor though. I measure my volume every 15 minutes in the boil to see if I’m on track. If I lost too much volume, I turn the heat down and vice versa.

You started your boil with 6 gallons so if you have a wide pot and boil hard you will easily boil off 2 gallons of liquid. You can leave behind another 1/2 gallon to cold break and hops. Did you use a lot of hops. 12lbs of grain shouldn’t absorb 2 gallons of water. You can continue to let the grains drain will you boil you should be able to get at least another 1/2 gallon of wort.

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If your PBG was 1.055 and your OG was 1.072 you are losing a lot to boil off (30% by my calculation which might be wrong) Either start with more volume or boil for less time or with less intensity.


I don’t use a calculation tool for water. I just did close to 1.5qt per lb of grain. As for hops, only 2.25 Oz pellets. I use a keggle for a kettle and had a pretty vigorous boil. I always assumed a loss of a gallon per hour boil. It must be more. I would say I left less than a half gal behind in the kettle. I have never thought to keep my grains draining during the boil. Great idea. I will adjust my system and factor in an additional 1.5 gal pre boil volume and see how it goes. Thanks everyone.



I was facing that problem when I first started and wondered how to calculate for grain absorption, boil off, trub loss, etc… You really don’t have to do it yourself. BREWGR.COM makes brewing and creating recipes so simple. It will allow you to enter grain weights, desired mash temp, current grain temps, mash thickness, etc and it self calculates the amount of water you will need at all the right temps.

This is only one small tool this free site has to offer. Check it out you won’t be disappointed. After you run a couple batches with this tool, you will start to understand the process better and be able to adjust your brew days with your experience.

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