so I will be doing a 2.5 gallons batch of IPA sunday along the lines of Hoppiness is an IPA from BCS (but Columbus insted of Horizon, Cascade instead of Simcoe for and Citra instead of Amarillo). I'll be performing my first partial mash with it. Also, I'll only do a partial boil because my stove can't do a full boil.
I use bottled water as I don't trust my apartment's water (yellow-ish for a few seconds when I open the tap). But the bottled water I bought is a little too soft. So I bought gypsum to adjust my water's concentration in Ca and SO4.
Is water chemistry only important during mash? I mean, if I only adjust my water during the mash, when I'll boil later on, the water will evaporate, leaving a greater concentration of Ca and SO4 (less water because of evaporation, same number of ions). Then, I'll need to top-off with water. But I'm worried about the ions' concentration. We don't want too much SO4 in the beer.
Do I need to adjust my top-off water with gypsum or only use distilled water to reestablished the original concentration?!
Or is this already taking into account by the tables in Palmer's book?