BeerSmith 2: Mash Volumes

In preparation for Saturdays brew day I have purchased beersmith2. I had been using the trial version and since the purchase i have made my own equipment profile. While looking at the water volumes i noticed that there are two different numbers for mashing volumes.

Tot Mash Water - reading 3.36 gallons
and
Mash Volume Needed - reading 4.20 gallons
(Sparge Vol - reading 4.18 gallons)

According to my calculations (10.75lb x 1.5) / 4 = 4.03125 gal/mash water.

I was wondering why there was a discrepancy between the 2 values that BeerSmith calculated. Is the Tot Mash Water value with grain absorption? Is there a hidden variable that is slipping my mind? Something to change deep inside BeerSmiths settings? Really, it isn't that big of a deal because i always calculate myself but i am curious to know.

Here is what BeerSmith website says:
Mash Water Volume - The total amount of water to add to the mash during mashing.

Total Water Needed - The total amount of water needed to brew this beer. Includes all top-ups, losses, sparge water, etc... This number is useful if you wish to prepare or treat the water all at once with water treatments, for example.

Total Mash "Volume" sounds to me like how much room it's going to take up in your mash tun. I would imagine that's to show you how close you are to overfilling.

It's not a measure of the water at all as far as I can figure.

Is the difference equal to your mash tun dead volume? You can change that setting in the equipment profile and see if that effects the numbers BS2 is giving you.

Mash Volume Needed - reading 4.20 gallons = the space needed in your mash tun

Wow, that was an obvious answer. Here is my problem with the calculations though:

Palmer says 1.5-2.0qts water/1lb grain and that is the formula i have always used when mashing.

Bear w/ me - i added a bit more grain from the previous post:

(11.11 x 1.5) / 4 = 4.16625 gallons of water

BeerSmith is suggesting 3.4725 gallons of water for my mash w/ estimated grain absorption of 1.33 gallons. If my goal is to collect half of my boil volume on my first runnings and half of the volume on second runnings there is no way that I can do that given the mash volumes calculated with BeerSmith.

I know my equipment so i have changed the boil off volumes slightly. i lose about 1.3gallons during a 90minute boil. My target preboil volume is 6.4gallons and my target post boil volume is 5.20 gallons. As you can see - using the mash volumes BeerSmith calculated i would not be able to collect half of my preboil volume on my first runnings.

I guess I will just use my formula like always - just dont understand what formula BeerSmith is using to calculate mash water volumes.

It's not really something to worry about IMO, I have never been able to collect half of my boil volume in first runnings and I use a 10 gal cooler that will handle 23# of grain for really big beers.

The way I find Beersmith usually works is that the total water volume needed is usually split into two. So if it calculates you need 10 gallons the strike will usually be around 4-5 and the batch sparge 5-6. This accounts for absorption and other losses that are in your equipment profile set up.

There are also default numbers that can be changed so if you want to strike at 1, 1.25, 1.5 or 2qts/lb you can change that as well. You also need to dial in the losses so your volumes match up. There is no absorption in the sparge.

If you do want to be able to collect half your volume then you need to adjust your strike volume to account for the absorption and losses yourself I believe or go in and change all the defaults accordingly.

What does the actual brew sheet say?

I've been using BS1 and BS2 for almost 3 years, and the only adjustment I have had to make to get the volumes correct is the adjustment I made 3 years ago for deadspace in my mash tun. Since then I have hit every pre-boil gravity either on the nose or within .001.

I re-calculated everything in BS for the first six months, but don't bother anymore because my equipment is basically dialed in.

I would suggest doing the beer and having some extra sparge water on hand. Check your numbers and dial in your equipment.

It certainly won't mess up your beer this time, and for the next time you'll be able to adjust the calculations in the program.

Good luck!

I also use a 10gallon cooler as well as a 10gallon blichmann boiler maker. I realized that BeerSmith was using 1.25qt/lb grain to calculate. I adjusted the mash ratio accordingly accounting for grain absorption and wanting my first runnings to equal half of my boil size. I will be mashing with 4.5825gal and sparging with 3.5gal in an effort to collect 6.4gallons of wort. I may end up using a little more water during sparge.

Does BS do a good job of calculating grain absorption?

It does an excellent job calculating everything as far as I can tell. It really pays off to measure everything extra precisely the first time you use it or any time you change your equipment.

It sounds like you have a similar setup to what I have. I have a copper manifold in a 10 gallon cooler (the round ones).

Every time Beersmith has been wrong over the last 3 years, it's been my fault.