Is everything a bit clearer to you now? If not, I wrote some stuff on efficiency a couple of days ago here
. There's two ways the BIABacus can "guess" how many sugars are available in your grain. Let me explain why I am using the word "guess" as this applies to all software.
Working out how much "sugar" is available in a recipe"
The home brewer actually has no way of knowing the real amount of "sugars" in his/her malt bill.
The amount of "sugars" available from a malt differ from year to year and even from malting to another. The maltster issues a grain specification sheet for each malting but most home brewers will find it hard or impossible to obtain a grain specification sheet for even the base malts they purchase. Even if you were able to obtain grain specification sheets for all the malts you bought for your batch, you still wouldn't know the moisture content at time of brewing unless you own a moisture meter so your prediction could, straight away, easily be at least a few percent out.
The first thing to recognise is that it is a bit of a myth that home brewers can know the amount of "sugar" available in a brew.
How other software gets around this - ambiguity etc.
Most software avoids the brewer thinking about the above by providing a generic value of a malts "sugar" value. It's very hard to find agreement on these values from one bit of software to another and where there is agreement, it is pretty obvious that one bit of software has copied directly from an older one. Another way that the software can get around it is to use very loose terminology or undefined terminology. For example, "Yield", is the term used in the most widely used software out there but that term is undefined and meaningless. In that software, when you change the moisture content of a malt it makes absolutely no change to the estimates. This is, without question, a critical and basic error.
How the BIABacus deals with this - Advanced Method
If you did have a Grain Specification Sheet and did know the moisture content of the malt, then The BIABacus is the only software (I've given up on checking up on other software) that enables you to enter that information properly and unambiguously via Section Y. As a user though, I would only ever consider using Section Y if my recipe had some ingredient in it that was out of the ordinary for an all-grain recipe such as malt extract or raw sugar because...
How the BIABacus deals with this - Default Method
What we did in the early days was run a lot of recipes through other software until we came up with an average "sugar prediction" for an average recipe. We then used this default in "The Calculator" (the pre-cursor to The BIABacus). Over the years, we have repeated this exercise many times against other software and found that, on all-grain recipes, there was very little variance. Since The BIABacus, we have been able to test further by seeing what differences there were on a recipe if we overrode our default by using Section Y. The difference on all-grain recipes was totally insignificant. (Try it yourself!)
Just stick with The BIABacus defaults unless your recipe has some very sugary ingredients in it or if you know that your particular base grain is known widely as being a bit dodgy, or particulary "out of spec" for that type of malt.
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