https://www.homebrewersassociation.org/homebrew-recipe/what-the-helles/
Start with RO water, adding minerals to achieve water profile: Ca = 44, Mg = 1, Na = 7, SO4 = 58, Cl = 41, and HCO3 = 20. Note: Acidulated malt was used to adjust RO water pH. Other liquid acid additions can be used in the mineral additions (phosphoric for example) in place of Acidulated malt if desired.
Double infusion mash. Protien rest at 122° F for 30 minutes. Saccharification rest at 154° F for 30 minutes. No mash out.
Sparge, collect runnings and boil for 90 minutes. Conduct a 20 minute whirlpool after knockout, adding hop additions.
Primary fermentation: Chill to 50° F and pitch starter yeast. Allow to free climb to 54° F. Diacetyl rest at 66° F for 3-days. After the diacetyl rest is complete transfer to secondary or dump yeast and slowly reduce temperature to 38° F. Lager for 30 days