Classic Oktoberfest Märzen

1.Mash:
Heat 4.5 gallons (17 L) of water to strike at 161^{\circ}F (72^{\circ}C).
Mash in your crushed grains, stirring to avoid dough balls. The temperature should stabilize at 152^{\circ}F (67^{\circ}C).
Hold this temperature for 60 minutes.

1. Mash Out & Sparge:
   After the 60-minute mash, raise the temperature of the mash to 168^{\circ}F (76^{\circ}C) and hold for 10 minutes. This is the mash-out, which stops enzymatic activity.
   Sparge (rinse) the grains with approximately 4 gallons (15 L) of 168^{\circ}F (76^{\circ}C) water, or until you have collected about 6.5 gallons (24.6 L) of wort in your kettle.
   
   
2. Boil (60 Minutes):
   Bring the wort to a rolling boil.
   @ 60 minutes: Add the 1.5 oz bittering hop addition.
   @ 15 minutes: Add the 0.5 oz flavor hop addition and your Irish Moss or Whirlfloc tablet.
   @ 10 minutes: Add the yeast nutrient.
   @ 0 minutes: Turn off the heat.
   
   
3. Chill:
   Chill the wort as rapidly as possible to your yeast pitching temperature, ideally around 48-50^{\circ}F (9-10^{\circ}C). An immersion chiller or counterflow chiller is essential for this.
   
   
4. Fermentation (The Most Important Step!):
   Transfer the chilled wort to a sanitized fermenter, leaving the trub (sediment) behind.
   Aerate the wort thoroughly by splashing or using an aeration stone.
   Pitch your yeast. If you made a starter, decant the liquid off the top and pitch the yeast slurry.
   Primary Fermentation: Ferment at a constant 50^{\circ}F (10^{\circ}C) for about 2 weeks, or until fermentation activity significantly slows.
   Diacetyl Rest: After primary fermentation, raise the temperature to 65^{\circ}F (18^{\circ}C) and hold for 2-3 days. This allows the yeast to clean up diacetyl, a compound that can taste like butter or butterscotch.
   Lagering: After the diacetyl rest, transfer the beer to a secondary vessel (like a carboy or keg) and slowly lower the temperature by about 5^{\circ}F (3^{\circ}C) per day until it reaches 34-38^{\circ}F (1-3^{\circ}C). Let the beer lager at this cold temperature for at least 4 to 6 weeks. Patience here is rewarded with a much smoother, cleaner beer.
   
   
5. Kegging / Bottling:
   After the lagering period, gently transfer the beer to a keg or bottling bucket.
   Kegging: Force carbonate to approx. 2.5 volumes of CO_2.
   Bottling: Prime with corn sugar and bottle condition for at least 3 weeks at room temperature before refrigerating.