Am brewing a Kolsch from a recipe. The recipe called for specific Wyeast or Whitelabs kolsch yeast strains that aren't available near me, so I decided to go for a German ale type yeast, also without luck. Settled on a Bohemian lager yeast, given that Kolsch beers are similar to lagers. That yeast wants to ferment at the 10 - 15 degree temperature range. The recipe wants the wort to ferment at 21 degrees, which to me seems high for the yeast type even if I had the recommended yeast. Anyway, fermentation started within 6 hours at 21 degrees and is still happily bubbling away near 48 hours.
Question: given the yeast type, should I drop the temp to, say, 15 degrees after say, day four, and then lager it for a couple of weeks, or just let it ride it out at 21 degrees and bottle and condition once fermentation has stopped. Pros and cons of either?