As I have learned recently learned, the main thing you want to focus on is your mash pH at room temp. You want it to be between 5.2 and 5.5. Bru n' Water is great because you can plug in your water profile, your recipe, and any water additions you make. Be sure to list if the grain you are putting in is a roasted grain or a crystal grain, as this will help to acidify the mash. You can use Calcium to help lower your pH along with delusion using RO water or distilled water. Once you get your pH in that range (found on the 'Mash Acidification' sheet) you will be good to go.
Another thing is to look at your sulfate to chloride ratio. You get these from calcium chloride and calcium sulfate (gypsum). A .5 ratio will give you a beer that highlights malt. Flip that ratio or even widen it (4:1 or even 7:1) and you will get the hop flavor you want.
Mash pH and Sulfate to Chloride ratio - those are the biggies.
I don't think that calcium lowers your pH, it buffers acids and thus can raise your pH. Roasted and crystal malts, acid malt, or just acid are used to lower pH. Salts, pickling lime, chalk, gypsum are used to either buffer acids or raise pH and to provide needed trace minerals to the yeast.
Calcium lowers the pH, and to a lesser extent Mg. The Ca reacts with phytin from the malt and produces an H+ ion, more H+ ions by definition result in a lower pH. Gypsum doesn't raise pH.
okay now I am confused. Calcium creates a more acidic solution? I thought it was an acid buffer. hmmm. well learn something new everyday.
From howtobrew.com by John Palmer.
'In 1953, P. Kohlbach determined that 3.5 equivalents (Eq) of calcium reacts with malt phytin to release 1 equivalent of hydrogen ions which can "neutralize" 1 equivalent of water alkalinity. Magnesium, the other water hardness ion, also works but to a lesser extent, needing 7 equivalents to neutralize 1 equivalent of alkalinity. Alkalinity which is not neutralized is termed "residual alkalinity" (abbreviated RA). On a per volume basis, this can be expressed as:
mEq/L RA = mEq/L Alkalinity - [(mEq/L Ca)/3.5 + (mEq/L Mg)/7]
where mEq/L is defined as milliequivalents per liter."