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Frequently Asked Questions - Different Values


Question: Why does ProMash give me different predicted gravity values for my All Grain recipe than a published recipe or other brewing software packages?
Answer: There are generally two reasons for the possible difference:
  1. The author of the recipe may have used a different mash efficiency number in the recipe formulation. Unfortunately, most published articles do not provide the mash efficiency (like they should) and it is up to us to figure it out. Generally speaking, if you enter the grain bill identically to the published recipe, you can determine the authors efficiency level by setting the efficiency higher or lower until the ProMash predicted gravity matches that of the recipe. However, once you find the authors efficiency number, you WANT to set the efficiency back to your systems rating (as that's what you will be mashing with) but still hit the authors targeted gravity. So, enter the author's efficiency number, click the "Efficiency Lock" button, set the recipe's efficiency to that of your system. ProMash will then automatically adjust the grain bill to match the desired OG using your system's efficiency level.

  2. The grain potentials the author (or other software package) used in the recipe may be different than the values in the ProMash database. Grain potential values change from crop to crop, year to year, grower to grower. While the potential ratings difference for any given malt is generally minor, they may exist. If you are using grain lot analysis sheets, it is trivial for you to change the potential of any grain in ProMash, on-the-fly in a recipe or permanently in the database. If you do not have a lot analysis of all your malts, we suggest simply using the defaults in ProMash and adjusting the base malt of the recipe slightly until you match the authors gravity prediction. It is far more important to obtain lot analysis sheets for your base malts, as they will compose the majority of the grain load. While potentials for specialty malts may also differ, they are generally used in such small quantities as to not throw a recipes predicted (or achieved) gravity off by much.

Question: Why does ProMash give higher gravity estimates for extract recipes with steeped grain than some other brewing software packages available?
Answer: Usually this is due to the fact that ProMash will properly account for the gravity contributions of steeped grains while many other programs will not. When you steep grain, you are actually performing a 'mini-mash', which must be accounted for (as steeped grains contribute gravity). Now, steeped grain will achieve much less efficiency than a standard mash (about 30% as compared to a 70% average for full mashes), and therefore contribute much less gravity than in a normal, full mash. When formulating an extract recipe using steeped grain in ProMash, set the recipe type to "Partial Mash" and the Efficiency to 30% or less (note this does not effect the extract entries, which always yield 100% of their gravity potential). For detailed help on this see the Tips and Tricks section on Steeping Grain in ProMash by Clicking Here.

We are aware of other brewing packages that will account for the gravity of the steeped grains by automatically setting grain yields low and not providing an option for you to set the yields differently. While this may be appropriate for a single recipe and a single style of brewing, recipes and brewing techniques will vary and this "automatic" reduction of gravity to account for steeped grains fails for many brewers. This may also be a cause of predicted gravity numbers not matching with ProMash. Check with your vendor to see if this is the method they use.

ProMash allows the brewer to set the extraction rates (through the efficiency rating) to match their own brewing techniques and style, not forcing an assumed rate on the brewer. We know you want complete control over your brewing process and your brewing software. We give you that control.

Question: Why does ProMash produce different IBU estimates for my recipes than in printed books, magazines or other software programs?
Answer: The difference may be due to several factors:
  1. The author of the recipe (or brewing software) may have used a different formulation type in the calculation. In ProMash, if you goto the System Settings, Hop Section, you will see there are four types of Hop Formulas to choose from (Rager, Tinseth, Garetz, Generic). You will notice that changing formulas from one to the other will change the IBU values is ProMash itself. So, in order to match IBU values in published articles or in other brewing software, you must be sure you are using the same equation type. Unfortunately most authors do not publish this, and many may in fact use their own proprietary formula. Many software programs (including ProMash) allow you to set the equation type to your preference.

    ProMash ships with the default Hop Equation set to 'Rager'. Rager is the oldest formula to be published and as such, is published more frequently in printed recipes. This is not to say Rager is the most accurate, only that it is the default in ProMash. You can change the equation type in the System Settings, Hop Section to Rager, Tinseth, Garetzor Generic.

  2. Are the alpha acid levels the same in the book or magazine article as the hops you are using in the ProMash recipe? Cascade from one grower will have different alpha levels than Cascade from another. Within a recipe you can change the AA levels by simply double clicking on a hop within the recipe's hop list, and changing the AA level (you can change the setting permanently in the Hop Database). If you have not set the AA level to match that of the hop in the article, you will never match IBU values regardless of the formula used.

  3. Are the hop forms the same? IE does the published recipe use whole hops while you are using pellets? Different forms of hops have different utilization values. ProMash ships with default values of 10% greater utilization for pellet hops and 2% greater utilization for plug hops. You can modify these defaults in the System Settings, Hop Section should you feel utilization values for pellet and plug hops differ. Whole hops are the baseline for every published IBU equation.
Concentrated Boils: Concentrated boils affect IBU values because the utilization is less in a concentrated boil due to higher wort density. ProMash will automatically account for lower utilization values in a concentrated boil in all equations (Rager, Garetz, Generic), with the exception of the Tinseth equation. Tinseth's equation is based on the 'average' gravity of the wort, not the final gravity as the other formulas are. As such, it is not an appropriate formula for concentrated boils (as you have 2 average gravities, the boil gravity and the gravity after dilution) and was intended for use with full wort boils only.

Recommendations: As many brewers ask us for our recommendation as to which Hop Formula is best for them, here is our opinion (please note this is an opinion only):

Brewers performing Full Wort Boils: Tinseth
Brewers performing Concentrated Boils: Rager

Question: Why does ProMash calculate my mash efficiency different than other brewing software packages available?
Answer: This is usually due to the fact that most other software packages only take into account the Original And Final gravities in determining what the mash efficiency was. This is fine in a perfect world, but assumes the measured volume of the final gravity was identical to the batch size specified in the recipe, which is rarely the case. For instance, if you boiled down 1/2 gallon further than anticipated, the gravity of that wort will be higher (although the extract content will be the same). Entering that as the final gravity for an efficiency determination would give you higher, incorrect value as the gravity of the wort was higher, but the volume of wort was not taken into account.

In order to determine efficiency properly, ProMash lets you specify the Wort Volume and Wort Gravity together, thus eliminating the 'perfect world' problems and allowing you to determine mash efficiency at any stage of the brewing process, from Pre-Boil to Post-Boil.

Additionally, if you take the gravity reading of wort in the fermenter, wort losses from the Kettle to the Fermenter must be taken into account, as those losses contain sugar and must be accounted for in the efficiency calculation. ProMash does this all automatically for you.

So, if you live in a perfect world, the method of OG-FG only efficiency calculations will match with ProMash (or very close...ProMash is also the only program to properly convert to extract weight for the determination, as pppg is not linear across SG ranges and some variance will occur because of this. Most other software programs assume the linear relationship). If you want an accurate measure of efficiency at any point of the brewing process, then ProMash is for you!