Alan,
There are three variables for a given amount of grain and a single infusion step...
- The amount of water to infuse
- The temperature of water you are adding
- The target temperature you are trying to achieve
Given a mash at a certain starting temperature, if you specify two then the other one is fixed. In BeerSmith for the mash profiles we chose for the user to specify the amount of water to add and the target temperature -- then BeerSmith calculates the temperature of the water to add from the other two.
Going back to your example - lets pretend we create a mash profile for 1 lb grain and the first step (at some step temperature you entered) adds 1.25 qts of water.
Now we want to add infusion step 2 which takes us to some higher temperature. Insert another step, set the target step temperature and then enter the amount of water desired to achieve your target water to grain ratio. For example, lets say we are going from 1.25 to 2.0 which means we add 0.75 qt of water.
Press OK for the second step and look at the list in the mash dialog. It will show you added 0.75 quarts of water at a calculated infusion temperature to achieve the desired step temperature. If you did not add enough water it will show "Error: Infusion temperature too high" which means that the infusion water would have to be above boiling to achieve the target temperature. In this case, add more water until you get to something below boiling.
Now lets pretend we have our 1 lb of grain mash profile with two steps that looks OK. What next? Well create a recipe and apply that new mash profile to it...you will see that the grain amounts, water amounts, and temperatures all get scaled to match the real recipe (not a 1 lb recipe) and real equipment you are using.
Another item to play with is the Strike/Infusion tool - it works along the same lines as the mash profiles but may be easier to see since it calculates in real time...you enter the initial conditions for a step, target temperature and amount of water to add and it outputs the temperature of the water needed to achieve that goal.
I hope this helps...and I appreciate your time!
Cheers!
Brad