My American Pale Ale has been fermenting away nicely for the past few days and I'm certain I'll be racking to secondary within a few days (after SG gets stable).

I'm curious: I've been keeping my primary stable at ~68°F using a 10 gallon utility bucket filled with water and 100-Watt fish tank heater; can I unplug the heater (I'd like to save the power) and just keep the secondary in the water bath? I live in Southern California, so the low will only be in the high 40's at worst, with the water bath probably averaging ~60°F.

I'm also going to be dry hopping 2oz of Cascade hops--will the lower temperature be good/bad for this purpose?

  • Also of note: I'm using Safale American (DCL/Fermentis #US-05) yeast. Though the yeast should theoretically be finished fermenting at this time. Commented Dec 14, 2011 at 1:10

3 Answers 3


Once fermentation is mostly complete, keeping the fermentor at the ideal temperature (68, in this case) is less important. The yeast tend to give off fusels and other off flavors at high temperatures mainly during the early stages of fermentation, so raising the temperature won't matter as much. Since fermentation is mostly complete, lowering the temperature won't hurt your final beer either, as the yeast has already completed. You're going to lower the temperature of the beer soon anyway, after packaging.

The only other thing you want to consider is temperature swings; consistent temperature tends to be better for the beer. But, since you've got your vessel in water the rapid swings will be minimized.

As to hops, you may have to experiment, but you'll likely discern no difference in flavor.

  • Thanks, I kinda assumed it wouldn't be so important, but I've mostly seen people asking about higher temperatures post-primary. Commented Dec 14, 2011 at 20:05

The lower temperature will give you clearer beer since it will cause the yeast to drop out quicker.

However, the low temperatures may defeat the purpose of the secondary fermentation - which is really a conditioning phase. The yeast need to be active in order to condition up the beer. The recommended fermentation ranges for US-05 are 59-75F. Some of the yeast will still be active at temperatures lower than 59F, but I'm not sure they'll still be active down to the high 40's. If the yeast still are active, they will take a much longer time to condition the beer.

If the primary only lasts a few (3-5 days) then the beer will need a fair amount of conditioning. You may want to consider keeping the beer at room temp for a week to be sure most of the byproducts have been metabolized. You can then drop the temperature, providing a cold crash to clear the beer.

  • Thanks, here's what I ended up doing/am going to do. Fermented in primary for 8 days, transferred to secondary. Secondary will be in water with heat on for ~6 days then I'm going to add some dry hops and turn the heat off for a week. After that, I'll bottle and let age another ~3 weeks at room temp. Commented Dec 22, 2011 at 18:04
  • Sounds like a good plan! Priming for 3 weeks at room temp will help condition the beer further if the cold week in secondary makes the yeast go dormant, so you have all the bases covered.
    – mdma
    Commented Dec 22, 2011 at 18:28

Also consider if you are bottling. Wouldn't you need the temperature to be high enough for the yeast to do its thing to carbonate the beer? I’m going through this right now with a colder secondary and I had to use a fish tank heater to keep it around 65 and I’m planning on making sure my beer is at least 65 before I bottle it.

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