Id be interested in hearing how this comes out for you and the process you used (recipe/mash/yeast/water/ ferm sched etc)
Im planning to brew an Alt in Jan to be ready in April.
I'll update, but recipe was:
5 lbs Munich I (Weyermann) (7.1 SRM) Grain 1 58.0 %
2 lbs 8.0 oz Floor Malted Bohemian Pilsner (Weyermann) (1.7 SRM) Grain 2 29.0 %
8.0 oz Caramunich III (Weyermann) (71.0 SRM) Grain 3 5.8 %
8.0 oz Special Roast (Briess) (50.0 SRM) Grain 4 5.8 %
2.0 oz Carafa Special I (Weyermann) (320.0 SRM) Grain 5 1.4 %
1.75 oz Hallertauer [4.10 %] - Boil 60.0 min Hop 6 30.5 IBUs
0.75 oz Hallertauer [4.10 %] - Boil 20.0 min Hop 7 7.9 IBUs
0.50 oz Hallertauer [4.10 %] - Boil 5.0 min Hop 8 1.7 IBUs
1.0 pkg German Ale (Wyeast Labs #1007) [124.21 ml] Yeast 9 -
Appropriately sized starter (I got abnormally fresh yeast from my LHBS, so it was about 1.3 L on the stir plate), and with my gear after 90 min boil I ended up just over 5 gallons into the fermenter at 1.050 OG. I've been fermenting it at a good and steady 58°F, which is where I've done all my hybrids in the past. It's my first ever Altbier, but the recipe is loosely based off of the recipe in BCS, so I don't think it could be all that bad.
I thought about doing a 3 step decoction mash (protein rest/conversion rest/mash out), but ended up settling on a boring 60 minute single infusion at 154 and doing my usual "sparge mash out" (where I drain the grain bed, add hot enough sparge water to bring the grain bed to 168-169° and let that rest for 10-15 before draining again). Active fermentation just stopped, and haven't checked FG yet, so I don't know where it ended up.
I'm planning on 3-4 weeks in primary at 58° followed by another 4 weeks in secondary "lagering" at 40° and getting hit with gelatin before I bottle it.
As far as water, I targeted the Bru'n Water "Dusseldorf (Boiled)" profile. Final water actually used was:
Ca 50
Mg 6
Na 32
SO4 83
Cl 41
HCO3 60
That was without needing any distilled/RO water, just some gypsum additions, (I love my water for that reason), and doesn't include the minute additions of neutralizing ~3ppm of chloramine w/ campden tabs. Mash pH of 5.3