Bru'n Bicarbonate - bitter

brewing a bitter, using pale ale profile.... The bicarbonate profile number is 180..... right now, mine is about 80 with RO dilution. Is there a "need" to be that high on bicarbonate? Does that level of bicarbonate "add" anything to the beer? Or, is it ok/good to be in the ballpark on the other numbers and undershoot the Bicarb?

Right now I am looking at -
Ca - 100
Mg - 5
Na - 8
Sulfate - 155
Chloride - 50
Bicarb - 75

By the time you get to mash pH most of the bicarbonate has been converted to carbonic acid (and thence to CO2) and thus removed from the mash. In the process of converting it absorbs protons (hydrogen ions) and that is its sole role in the mash. Thus you need enough to neutralize the acids from dark malts and no more.

The bicarb value you want in your mashing water is dependent solely upon the effect on mash pH. In the case of the Pale Ale profile with its very high Ca and Mg concentrations, there MIGHT be a need for the bicarb. But its also dependent upon the grist.

I see that Braufessor has a much lower Ca and Mg level planned. Under that condition, there is probably little need to have a bicarb concentration as assumed for the Pale Ale profile.

Remember, Ca, Mg, and HCO3 are inter-related in the mash. If the Ca and/or Mg go down, then the HCO3 can probably be reduced too.