Water volume calcs

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ChiknNutz

Well-Known Member
Joined
May 3, 2020
Messages
391
Reaction score
213
Location
Advance, NC
I am still only one batch into BIAB brewing, so trying to dial in water volume. I am using both the calcs here listed below and get different starting volumes.
Brew in a Bag (BIAB) Calculator ~ and
https://pricelessbrewing.github.io/BiabCalc/#Advanced
For this particular batch, the BIAB calc says I need 7.38G of starting water. Using the same input values, Priceless says I need 7.62G of starting water. I have to assume each uses a slightly different algorithm to arrive at the values, but wondering which one tends to be more accurate...or if a different one altogether. I've also tried the BEER-N-BBQ spreadsheet but that one seems very far off for a BIAB batch as compared to the others and doesn't have the malts I'm using.

What do you use for calculating water volume?
 
I don't use either of those tools (I use BrewCipher). But to know how much total water you need to get "X" gallons into a fermenter, any accurate calculation would need to know the following parameters...

- Grain Absorption loss (per lb of grain)
- Boil Off per unit of time (and the batch boil time)
- Hop Trub Wort Loss (per ounce of hops)
- Kettle Deadspace (if applicable)
- Mash Tun Deadspace (not normally applicable to BIAB)
- Hose/Pump/Siphon Loss

They may be called something different in the tools you're using (if the tools consider them at all).
 
There are a few variables based on your equipment and process that will refine your use of these calculators. You'll see in the calculations it looks at your boil-off rate, your trub/chiller/equipment loss, and your grain/water ratio. These along with your batch info (grain weight, batch size, etc.) will provide a more dialed in calculation for how much water you need. I also suggest tracking your actual volumes during the brew day for consistency.

If you don't know the boil off rate you can run a few tests with water to get a general idea. Also, I'm not familiar with your system setup, but if you have a pump/hoses/cfc or anything else that will reduce the amount of wort getting into your fermenter you should track it under the trub loss field in the calculators as well. Lastly, your water/grain ratio is more dependent on the style you're brewing, but BIAB generally has a higher water/grain ratio.
 
Dude, you’re not going to notice the .24 gallon difference IMHO. I tend to use the biabcalculator.com as It has been easier to use for me. Most of my brews start with 7.75 to 8.25 gallons for full volume no sparge mash.
 
Nobody knows your specific boil off nor your absorption rates. Use one or the other, take careful notes and plug your adjusted numbers in the next time. In 2 or 3 efforts you will have it nailed down.
 
Yeah there's just so many variables, it's really specific to your equipment and method, in my view neither calculator can tell you, just keep good notes and make sure your process is consistent. For example I started with the same calculators telling me about the same as what you've said, but I now know that 7.62 gallons of starting water would probably give me barely 4.75 into my primary and I'd probably have to transfer a bit of trub to get that much. I would also exceed my target OG by probably 3 points. So I quit using the calculator, I just know what my numbers are.
 
The specific paramters of OP do not matter as far as comparing the calculators... as long as you plug in the same values, you'd expect results to be close.

what numbers are you using? I just gave both a try and i got 7.25 vs 7.22 G of starting water, which are close enough to be considered the same. The small difference is likely related to hop bill and hop absorption, which you can enter in priceless but not in BIAB (some assumption is probably made by BIAB). 0.24 G is a large difference for a calculator (whether it matters or not is totally dependent on what your goals are w.r.t brewing. I can tell you it matters to me)
 
I am wondering about water calculations myself. I have heard that for All Grain kits using BIAB 1.25 qts per pound of grain is a good ratio to start with. If I am brewing using 12 pounds of grain that would be 3.75 gallons in the mash. Would I then just top off to get to my 5 gallon batch?
 
I am wondering about water calculations myself. I have heard that for All Grain kits using BIAB 1.25 qts per pound of grain is a good ratio to start with. If I am brewing using 12 pounds of grain that would be 3.75 gallons in the mash. Would I then just top off to get to my 5 gallon batch?

1.25 qts / lb is the mash thickness for more traditional mash tun setup with batch sparging or fly sparging to get the rest of required volume....

I use 2.5 - 3 qts/lb for my 6gal BIAB batches... 12-13lbs of grain starts with 6-7.5 gallons and then a 1-1.5 gallon dunk sparge... I look to have 7gals at the start of the boil.

Full volume BIAB (no sparge) starts with *ALL* the water necessary to reach the desired final volume. You don't worry about mash thickness..

If you do decide to mash thick, you don't want to just top up off, though... You'll be leaving a lot of the sugars behind. At least do a "pour over" sparge to extract more of that sweet goodness...
 
So do you usually plan on 1 gallon boil off loss per 60 min boil?

That would depend on things like the vigor of your boil and surface area of your kettle. You can test it with water and a shorter boil, then do the math.
 
Ok cool cool. So do you usually plan on 1 gallon boil off loss per 60 min boil?

Yeah, 1 gallon per hour is about what I get for my set up... I do stovetop on a gas stove and supplement w/ an electric heat stick...

As mentioned by VikeMan, vigor of boil and diameter of your kettle play a role... 1 g/hr is a good first guess, but the only way to know for sure is track your volumes and measure it for your set up...
 
Guess I gotta do the work haha, so getting into the science of this- if I tested this does water type make a huge difference or does it come down to heat and surface area? (I have to use bottled water rather than my tap water when I actually brew).
 
It's not that complicated, water type shouldn't make much difference... Tap should be fine.... Measure out a gallon or 2 in your kettle and boil it. You can boil for just 15 min. if you like... The math is almost the same.

The less water you use the shorter you should boil so as not to run dry.

There will be some error in boiling less water or a shorter time, but it'll give you a good 1st estimate.

Then on your next full batch, keep track of volumes, and you'll have another data point. After a couple of batches, you should have a solid idea of your boil off rate.

I use a "witness stick" to measure volumes... I put notches in a long wooden dowel at the 1gal, 2gal, 3gal, etc. level. Then to know my volumes, I just put the stick in and see where the water level falls on my stick.... I don't even have 1/2 gallon marks... I just eyeball the in betweens...

You could also etch gallon markings into your kettle (there's a thread here on how to do it), or use a long stainless ruler.. Lots of ways to easily estimate volumes.
 
I am wondering about water calculations myself. I have heard that for All Grain kits using BIAB 1.25 qts per pound of grain is a good ratio to start with. If I am brewing using 12 pounds of grain that would be 3.75 gallons in the mash. Would I then just top off to get to my 5 gallon batch?

Even dunk sparging in room temp/cold water will be better than just topping off... say you can't be bothered to heat up water a second time. I found these 2 videos from mash hacks very informative when i started out with all grain.

water volume calcs:


basic (simplest) all grain brew day
 
Even dunk sparging in room temp/cold water will be better than just topping off... say you can't be bothered to heat up water a second time.

You get almost exactly the same amount of sugars washed from the grain with cool water as you do with hot. The difference is in the time it takes to get the wort to the boil. Since the grains are wet and hot, they heat up the sparge water a considerable amount so the difference in getting to the boil is minimal.
 
FYI, I have pretty well landed on using the Priceless BIAB calculator and have had good results since using it. I also use a witness stick (calibrated length of plex tubing I had) for measuring volume.
 
I second @soccerdad

You have *GOT* to know your boil off rate. And it'll vary a bit each time, but the best thing is to fill the actual boil kettle and do an actual 30m boil and make some actual measurements.

Absorption rate is more variable for those who squeeze, vs those of us who gravity drip, vs any other number of methods. You're just gonna have to suffer the slings and arrows of outrageous fortune and keep notes and "dial in" your process/system/methods. And be prepared for bumps in the road when you do your first batch with lots of wheat and or oats.

But keep notes.
 
I use bag squeezing as a tool to hit the numbers. It's not necessarily something you're at the mercy of. Enter something conservative in your software... say 0.1-0.12 gal/lbs. This will give you a pre boil volume. When you pull out your bag, let it drain and give it enough squeeze until you hit that pre boil volume exactly. If you feel like you could have squeezed a bit more out, reduce the absorbtion for the next brew. Again squeeze until you hit the volume the software predicts. You'll get the expected pre boil volume every time.

you can play with boil off rate a bit as well, though it's less controllable. If you put in 1 gal/h, check if you've lost about half a gallon after 30 mins. if less, crank up the heat a bit, if more, reduce or cover the kettle a bit. Again you have some control to hit your numbers.

a sight glass on your pot is pretty useful for this.
 
I use bag squeezing as a tool to hit the numbers. It's not necessarily something you're at the mercy of. Enter something conservative in your software... say 0.1-0.12 gal/lbs. This will give you a pre boil volume. When you pull out your bag, let it drain and give it enough squeeze until you hit that pre boil volume exactly. If you feel like you could have squeezed a bit more out, reduce the absorbtion for the next brew. Again squeeze until you hit the volume the software predicts. You'll get the expected pre boil volume every time.

you can play with boil off rate a bit as well, though it's less controllable. If you put in 1 gal/h, check if you've lost about half a gallon after 30 mins. if less, crank up the heat a bit, if more, reduce or cover the kettle a bit. Again you have some control to hit your numbers.

a sight glass on your pot is pretty useful for this.
What is your preferred software?
 
What is your preferred software?

short answer:
brewfather. I've started using it about a month ago and i am impressed. Will probably become my only tool once i've got everything dialed in and agreeing with other calculators i've used.

long answer:
I've used beer smith for some time. I usually compare with other calculator, including the priceless biab calculator mentioned above. Priceless is probably the easiest way to go, as it is one pager that's easy to understand and fill out. I also have my own spreadsheet which I've stolen from @doug293cz and modified a tiny bit.

Personally i like beer math and all the numbers. I understand playing with 3-4 calculators at once and comparing stuff is totally overkill. So if I were you i'd play with Priceless to figure out volumes and gravities... it's not a recipe builder however, so Brewfather would be my software of choice in the end.
 
So I just did a test at 2 gallons for 30 minutes. I boiled off a quarter of a gallon. So it looks like I will be at .5 gallon for a 60 minute boil with my set up.
 
Even dunk sparging in room temp/cold water will be better than just topping off... say you can't be bothered to heat up water a second time. I found these 2 videos from mash hacks very informative when i started out with all grain.

water volume calcs:


basic (simplest) all grain brew day


Question for you - when did you test your OG gravity? If I test after I've done my boil and it has cooled can I still heat it back up and add DME?
 
Question for you - when did you test your OG gravity? If I test after I've done my boil and it has cooled can I still heat it back up and add DME?
you can do that. You can also take a sample towards the end of the boil, let it cool a bit and take a gravity measurement with temperature adjustment. Keep in mind that if
1- your pre boil volume is correct
2- your pre boil gravity is correct
3- your post boil volume is correct
then your post boil gravity must also be on target.

so if 1 and 2 are correct then it's just a matter of hitting the right final volume and then the gravity will be right. You can tweak the heat during the boil to get there.

one thing I meant to ask on this forum as i dont know the answer: Assuming you remove the hops (using a bag or a spider), can you keep boiling longer than schedule without affecting IBU?
 
Assuming you remove the hops (using a bag or a spider), can you keep boiling longer than schedule without affecting IBU?

You will still have some non-isomerized alpha acids in the wort after you remove the hops. If you keep boiling (or even just keep the temperature high), they will continue to isomerize and add bitterness.
 
You will still have some non-isomerized alpha acids in the wort after you remove the hops. If you keep boiling (or even just keep the temperature high), they will continue to isomerize and add bitterness.
Will there be a big difference in bitter flavor then if I heat it back up just to add the DME for a boost?
 
Will there be a big difference in bitter flavor then if I heat it back up just to add the DME for a boost?
you could probably dissolve the DME in a separate pot of boiling water and add it to your cooling wort. Will be faster than reheating your whole wort. Probably some math to be done here as you'll be adding some liquid as well... but it could be very concentrated I imagine. Just guessing, I've never really done the DME addition. If it's off... oh well, adjust for the next batch. The difference in final product will likely not be huge. Since you're just one batch in, you'll likely still be happy withe the beer you make and you'll fine tune as you move forward.
 
you could probably dissolve the DME in a separate pot of boiling water and add it to your cooling wort. Will be faster than reheating your whole wort. Probably some math to be done here as you'll be adding some liquid as well... but it could be very concentrated I imagine. Just guessing, I've never really done the DME addition. If it's off... oh well, adjust for the next batch. The difference in final product will likely not be huge. Since you're just one batch in, you'll likely still be happy withe the beer you make and you'll fine tune as you move forward.

Smarttttttttt -- thanks!
1597353349804.png
 
Back
Top