I got a good deal on an all grain kit, it's a chocolate stout with 11 pound grain bill. Link to Brew Cipher PDF export All grain 5 gal Chocolate Stout 9 lbs pale malt 12 oz (0.75#) Chocolate malt 2 oz (0.125#) Roasted Barley 2 oz (0.125#) Black Patent 8 oz (0.5#) English Crystal / Medium Caramel 8 oz (0.5#) flaked oats) 1 oz Belgian cocoa powder 1 oz Willamette hops @ 60 min (4.8 AA) - which I can't change in Brew Cipher FYI I was going to batch sarge (I am only set up to batch sarge, or no sarge). Target 150 F for mash. Target mash pH of 5.5 Was going to use RO water and adjust with minerals to reach 5.5 pH and replicate a Dublin - London water profile. 2.5 ml of lactic acid and 3 ml of phosphoric acid isn't too much is it? *Note: I made an assumption that the RO water will have a pH of 6. I have no idea what the pH of the RO water will be(I assumed it would be 7 THB). I googled it and that seems to be an average. I'll have to adjust on brewday, but this is a starting point to work from.
You shouldn't need any acids for a stout. In fact you'll probably need some slaked lime or baking soda to raise your ph. You might want to look at that again.
Plugging this recipe in brecipher, I would make the following mineral additions to RO water, strike water 1.5 qt/lb. Add to mash- 1g CaCl2, 1g CaSO4, 1g CaOH2 Add to kettle- 5g CaCl2, 2g CaSO4
How much chocolate flavor are you looking for? I make a mint chocolate porter that has a good amount of chocolate flavor. I use powder as well. I use 8 oz in to 5 gallons. I bring some extra runnings to a boil, kill the heat, stir in the powder, cover and let cool while I finish the rest of brewday. This pasteurizes it and it's room temp by the time I need to dump it in primary. I then let it sit for 2 weeks in primary. I've brewed this 4 times and the only time I didn't get the chocolate flavor I wanted was the 4th time when I screwed up my water chemistry (too soft). I think that 1 oz will not even be noticeable. I get a good amount of flavor with 8 oz/5 gallons for 2 weeks. You may not want that much, but I think 1 oz is just wasted.
Because your mash ph would be way off. You only want to add enough minerals to mash to get your Ca up to 50, and achieve your desired ph. The kettle additions are for flavor. Its how you adjust your Cl/SO4 ratios. Higher SO4 accentuate bitterness, leading to drier, cleaner finish. Higher Cl leads to a fuller, malty finish- which for your stout is what you want. Its really just that simple. Good luck!
Actually I don't think you even need to get your calcium up to 50 in the mash. The calcium is for the yeast - it can go into the kettle. To give a little more detail, calcium and to a lesser extent magnesium lower the pH of the mash. In a light beer that can be a good thing, and so often it makes sense to add the salts to the mash. But in a dark beer, the roasted grains will likely push the mash pH below the optimal range, and so shifting salts to the kettle helps prevent the pH from going too low.
I'm more a fan of getting the mash pH correct and everything else follows... May take a bit more effort in pH adjustment, but it makes more sense in my head.
If you're concerned about the mash pH calculations, the pH of your starting water doesn't matter. BrewCipher (mph actually) ignores the strike water pH and uses the strike water's ions and alkalinity in the mash pH calcs. The only place the water's starting pH is used is for the sparge water acidification calculation. For your RO water, you could use 7.0 (the theoretical pH of pure water) or something like 6.0 (where "pure" water wanders toward as atmospheric CO2 is dissolved into it). It won't matter much, because the difference in volume of acid needed in each case will be smaller than a typical homebrewer's ability to measure. (The reason is that RO water has so little buffering capacity.) Of course, if you're batch sparging with RO water, there's no need to acidify it anyway.
Calcium additions may be necessary to assure sufficient enzyme activity for mashes in water that is low in calcium. (Water, pg. 45) ...so to me that means > 50ppm for RO water
