Batch size: 5 gallons (19 liters)
Brewhouse efficiency: 72%
10 lb (4.5 kg) Weyermann Extra-Pale Premium Pilsner
0.4 lb (181 g) Weyermann Carafoam
Calcium carbonate and calcium sulfate 3:1 to 50 ppm calcium, according to your water profile
1.5 oz (42 g) Tettnanger [5% AA] at 20 minutes
Lots of Saflager W-34/70 Lager Dry Yeast, White Labs WLP830 (German Lager), or Wyeast 2124 (Bohemian Lager). A two-step starter of 2 quarts (1.9 l) to 1 gallon (3.8 l) should give you enough from a healthy package of liquid yeast. Or simply spring for four packages to ensure a quick and full fermentation.
Dough in with 13 quarts (12.3 l) water to hit 150°F (66°C) for 60 minutes, then add 5.5 quarts (5.2 l) of boiling water to mash out. Vorlauf and lauter as usual but keep in mind that your boil off will be about 25 percent of normal. Either collect only 5.5 gallons (20.8 l) or plan to have some extra beer. Then hold the wort in the boil kettle as close to 170°F (77°C) as you can (lid off!) for 100 minutes. Bring to a boil and add the single hop addition. (Feel free to substitute an equivalent IBU of your favorite low-alpha German hop.) Shut it down after 20 minutes of rolling boil.
Chill the wort rapidly to slightly below fermentation temperature, about 50°F (10°C). Aerate the wort and pitch the yeast.
Hold the temperature as close to 50–52°F (10–11°C) as you can for 2 weeks before slowly lowering it to 36–38°F (2–3°C) and transferring to secondary for a 3-week lager. Package as usual.
In my experiment, acidulation was done with lactic acid, but you can also replace some of the Pilsner malt with Weyermann Acidulated malt. You should be able to move pH down about 0.1 with each percent of the grist.
To chill this wort quickly, you’ll want to pull out all the stops. Keep in mind the current temperature of your groundwater! If you have an immersion chiller, combine it with an ice bath and near continuous stirring to reach that 100°F (38°C) mark. I’ve seen this happen in as little as 12 minutes in the summer. Running an immersion chiller in an ice bath as a pre-chiller for a plate chiller will allow your wort to run very fast and also give an excellent cold break.