This is a 3.5 gal BIAB batch, full volume mash starting with 5.78 USGAL of water. My city tap water is generally pretty hard (60ppm Ca, 17.8ppm Mg, 32 ppm Cl, 152ppm bicarb), therefore I was going to cut it pretty hard with RO water, 3.8 gal of RO water and 1.4 gal of tap. Then, based on Beersmith's water profile tool, I was going to add .6g Gypsum, 3.8g MgSO4, 2.2g CaCl in order to get a good mineral profile and SO4/Cl ratio. This would bring me to 54ppm Ca, 17.8ppm Mg, 107ppm SO4, 63ppm Cl and 41ppm HCO3...all in the range I'm looking for. Problem is then Beersmith estimates my mash pH at 5.7 and then comes in the phosphoric addition (now 84mL into 23qt of mash water) for a 3.5 gal batch. The grain bill is pretty simple but a lot of light grains
6.5lb Pale 2 Row
14oz wheat malt
7 oz Carapils
3.8 oz crystal 10L
7oz Dextrose
Now, I'm well aware that I haven't actually mashed this malt bill yet and therefore haven't made a real world measurement, but my initial question still stands. Beersmith predicts a mash pH of 5.71 and if I desire to hit 5.2, it tells me that an addtion of 10% phosphoric acid at 84.7mL is needed. Am I doing some thing wrong here because that sounds like a large volume of acid to add to a 3.5gal batch? Again, thanks for any assistance.