Ditch the chalk. Only needed for dark beers to increase pH. Martin has said before that it doesn’t even work unless you dissolve in water with co2. I could see needing the lactic with such a light colored beer, but if you are between 5.4 and 5.5 without, I’d say skip. Chalk and lactic are actually counter productive in your case.
You should be fine with gypsum and a bit of calcium chloride. I’ll play with the numbers when I get to my computer.
And if you are using RO, acid doesn’t need to be added to sparge. You shouldn’t add chalk to sparge anyhow as it won’t dissolve.
I recently brewed a pseudo Munich Helles with US-05 yeast (therefore it is actually a Blonde) and it came out very nice. Actually served it last night at the FBI Monthly meeting.
I used a water profile similar to the boiled Munich water shown in Bru’n Water. All the minerals were added to the mashing water only (the sparging water additions too) so that the Ca content in the mash would be high enough to precipitate oxalate. That left the overall wort with a somewhat low Ca content around 30 ppm when the sparging water was added. Very nice light flavor that was focused on malt. The ferment was at 53F to 54F and the US-05 left the beer with only very light esters. Not a bad compromise to avoid dealing with preparing a lager yeast starter.
Sounds good. I brew a lot of blondes and I want to move to a softer lighter flavor.
I just moved so I decided to go with RO water. I plan to experiment with different water profiles over time. I like the idea of a balance between hops and malt for this first try. I usually add all the hops in the last 15 minutes for a hoppy blonde.