Mash volume and water to grist ratio calculations correct for BIAB equipment/ mash profiles with recoverable mash tun deadspace?

[mahleywc]

I have a Spike 15 gallon Solo. I use the standard equipment profile provided for this system. The profile is only modified for a 5.5 gallon batch size and Trub Loss to account for additional chiller and plumbing losses. The profile has Mash and Lautering Adjustments as follows:

• Recoverable Deadspace: 4.00 gal
• Mash Losses: 0.00 gal
• Adj mash for deadspace NOT CHECKED

First, the Solo recoverable dead space varies with water volume due to the tapered basket. This may need to be adjusted manually if it becomes significant.

Most importantly, it appears the recoverable dead space is not subtracted for the water to grist calculation! The first mash step shows a Water/Grain Ratio based on the total water needed. This clearly is incorrect. The Adj mash for deadspace setting does nothing to correct this of course. In my recipe example with 13.75 pounds of grain and a BeerSmith calculated total water needed of 8.63 gallons of water the BeerSmith calculated Water/Grain Ratio is 2.511 qt/lb. The correct Water/Grain Ratio should be 1.36 qt/lb. Even more significant is that a 15 gallon Solo system with this recipe has only 16.11 quarts available for grist contact giving a Water/Grain Ratio of 1.17 qt/lb. While this ratio is marginally adequate for this recipe a slightly larger grain bill would yield an inadequate Water/Grain Ratio.

This issue affects any BIAB system with significant recoverable dead space under the bag/basket. It is particularly amplified in larger Solo systems. Can this be corrected in the calculations please?

 

[BeerSmith]

Could you send me a sample recipe (BSMX format - just right click on it and export selected) to beersmith at beersmith.com - I want to take a look at this in detail and confirm it. I'm working on updates now so if this is a bug I want to get it into the next set of updates.

 

[mahleywc]

Example recipe highlighting this issues has been sent as requested.

thank you!

 

[mahleywc]

Could you send me a sample recipe (BSMX format - just right click on it and export selected) to beersmith at beersmith.com - I want to take a look at this in detail and confirm it. I'm working on updates now so if this is a bug I want to get it into the next set of updates.

I sent you an email with a recipe that highlights the issue on 6/23/23. I’m just wondering if you have received it. Thanks!

 

[BeerSmith]

Yes - sorry but I was at Homebrewcon in San Diego last week and I've been catching up on things this week.

Looking at the recipe itself, you are using a BIAB mash profile which basically means all of the water needed for the boil will be used in the mash no matter what the other settings are. This is done for all BIAB mash profiles as the baseline for BIAB is that there is no sparge and so all of the water will be added up front. Basically since your losses are recoverable, there is no way you can add more water to the mash than you will need in the boil unless you want to just add extra water for no reason (in which case you would probably add that as tun deadspace since it is lost water.)

As for the water/grain ratio in the first step, while it could be calculated excluding the recoverable deadspace, I'm betting your particular system (like many BIAB style systems) recirculates the mash water continuously so you really don't have just a few gallons sitting statically on the grain bed.

If I turn off the BIAB flag in the mash profile you will see that the mash volume jumps way up to 57 quarts in an attempt to meet the 2.57 qt/lb water/grain ratio you have set for the mash step but this results in a negative sparge volume which is probably not what you want. This is why most BIAB style systems use the BIAB mash profile settings to get as much water into the mash as possible.

Brad

 

[mahleywc]

Yes - sorry but I was at Homebrewcon in San Diego last week and I've been catching up on things this week.

Looking at the recipe itself, you are using a BIAB mash profile which basically means all of the water needed for the boil will be used in the mash no matter what the other settings are. This is done for all BIAB mash profiles as the baseline for BIAB is that there is no sparge and so all of the water will be added up front. Basically since your losses are recoverable, there is no way you can add more water to the mash than you will need in the boil unless you want to just add extra water for no reason (in which case you would probably add that as tun deadspace since it is lost water.)

As for the water/grain ratio in the first step, while it could be calculated excluding the recoverable deadspace, I'm betting your particular system (like many BIAB style systems) recirculates the mash water continuously so you really don't have just a few gallons sitting statically on the grain bed.

If I turn off the BIAB flag in the mash profile you will see that the mash volume jumps way up to 57 quarts in an attempt to meet the 2.57 qt/lb water/grain ratio you have set for the mash step but this results in a negative sparge volume which is probably not what you want. This is why most BIAB style systems use the BIAB mash profile settings to get as much water into the mash as possible.

Brad

Yup, I understand all you have said. And yes I do employ mash recirculation. Regardless, my practice is to maintain a 1qt/lb ratio by increasing the strike Water and upping the boil time. It would just be nice if the calculatio for the water/grain ratio worked the same as they do for non-BIAB mash profiles and displayed in the fixed grayed-out field.

So, I wonder why Spike and the user community have noted caveats about the significantly reduced water to grain ratios in the basket as a result of their basket design? I’ve attached their Q&A document. I have done a lot of looking, and have seen a lot of opinion, but no actual study results regarding the impact of the Spike Solo-like environment on enzyme effectiveness and sugars extraction, where the grain bed is dene (<=1qt/lb) and the enzymes are diluted and recirculated through a relatively large recoverable dead space. Might not be significant, but…

 

[BeerSmith]

The huge recoverable deadspace is a bit of a problem in many of these designs, but the recirculation largely makes up for it by moving the entire volume of wort through the mash. You just need to recirculate slowly so you don't get large channels in the grain bed.

As an experiment I played with your recipe a bit more. I turned the BIAB off to see what it would do if I set a fixed water/grain ratio. Then I set the water/grain ratio for the mash step to 1.0 qt/lb (as you mentioned which would be the bare minimum for me). The program then calculated the initial strike at 35.25 qt which is correct as that's basically the sum of the recoverable mash tun deadspace plus the 1.0 qt/lb of water for the grains. I certainly would not want it to just include only the mash water for the grain here as it would leave the grain bed completely dry.

The reality is most of the BIAB style "all in one" systems work as a BIAB system and include the full boil volume in the mash and then recirculate to achieve good efficiency and clarity. In any true BIAB system you do give up control over the precise water/grain ratio and typically these systems use much higher water/grain ratios as a result (2-4 qt/lb is not unusual).

 

[mahleywc]

Geez! I really appreciate the extra time you put into this question. I had done the same thing to verify my tapered mash basket model results and yup, BeerSmith comes up with the correct answer if you turn off BIAB and plug in 1 qt/lb and the actual recoverable deadspace (that my model calculates). If the resulting total water is greater than the BIAB result the difference, if added, would then need to be boiled off. This might be a good tip for all the Spike Solo Users. They can use the Spike Solo deadspace table to figure out the variable deadspace. Bottom line…, my Belgian Quad gets brewed in my 3-vessel setup…

 

[BeerSmith]

No problem!