Bru'n Water 4.2 vs 5.3 vs 5.5: predictions are getting worse for me

[Horseflesh]

Martin sent out the newest version 5.5 the other day, but I'm not seeing any improvement in prediction. Here is an example.

In version 4.2, a simple pils recipe was predicted to be pH 5.4. I measured 5.34. Not bad!

Plugging all the same data into version 5.3, the prediction is 5.21.

In version 5.5, the prediction is down to 5.09.

I am using a very thin mash, since I am doing 5 gallon batches in a giant recirculating EBIAB pot. Since I am making small batches in a big system, I have about 4 gallons of deadspace under the basket. In this recipe I used 9.68 gallons of water to 12.75 lbs of grain. That is 6.33 l/kg or 3.04 qt/lb.

(I have read that mash thickness/pH calculations should always use total water volume, but I have also read that it should disregard the recoverable dead space volume. Under that rule my thickness would be about 1.8 qt/gal.)

I don't know what to believe about that, but I do know that I am sticking with version 4.2 for the time being since it produced good predictions for my gear.

 

[FunkedOut]

If you’re recirculating the whole time, use total water volume.

An argument can be made for ignoring dead space not mixing with the grist in a still mash.

Haven’t received 5.5 yet.

 

[Horseflesh]

If you’re recirculating the whole time, use total water volume.

That was what made sense to me, and how I have been doing it.

 

[ajdelange]

(I have read that mash thickness/pH calculations should always use total water volume, but I have also read that it should disregard the recoverable dead space volume. Under that rule my thickness would be about 1.8 qt/gal.)

I don't know what to believe about that,

If you are starting with water that has alkalinity then yes, you need to consider the total volume because 30 L of water contains 1.5 times the amount of bicarbonate (alkalinity source) as 20 L but if you are using RO or DI water the water volume has very little effect (only the alkalinity of the water itself and that's tiny). Check the program by telling it you are using distilled water. If varying the volume of that water changes the predicted pH by a noticeable amount, use another program. The one you have is not handling the chemistry properly.