Sulfury smell from airlocks

I started 2-5 gallon batches of cider on Saturday. They’re in 6 gallon carboys for lots of head space so I wouldn’t have to bother with using blow off tubes. Seems appropriate for beer, so why not cider? I’ll rack to secondary in 5 gallon carboys to reduce head space and oxidation. I’ve learned a lot from this list and books since I last fermented cider 2 years ago, so I’m doing a lot of different things. First off, I hear loud and clear that temperature control is paramount. So I have my two carboys in a big Rubbermaid tote filled with water and ice packs. Works beautifully! The water temperature has been ranging from 58 to 62 degrees, and the airlocks are bubbling 20 bpm (bubbles per minute). Decided to stick with Cote de Blanc for both batches as I plan to experiment with these 2 batches and wanted to eliminate yeast as a variable at this point. But I’m finding this setup to be so easy that I might actually consider trying to lager something this winter since my house is usually about low 60’s anyway. I could just leave a stock pile of ice packs to let winter refreeze them outside (a benefit of working in the health industry is endless supplies of ice packs) and just keep tossing them in. I bet I could get that tote water down to 45 degrees if I changed the ice packs often enough.

 Here's an observation I made this morning.  I am smelling a bit of a sulfur smell coming from the airlocks.  I don't remember this 2 years ago.  I did pasteurize the cider and quick chilled with my IC.  I have never lagered a beer before, but I have read that DMS can be present when lagering.  Is that a factor of the yeast or the cold temperature?  It's already less noticeable this afternoon.  Since I am fermenting this cider 15 to 20 degrees cooler than I last fermented cider, I suspect a lot of things will be different.  Anybody think the sulfury smell is due to the cold fermentation temperature, or do you think I have a contaminant?  The krauzen is already an inch thick, so the yeast is taking it's job very seriously it seems.

Sulfur is very normal in cider. Don’t worry, it disappears completely in a few weeks.

DMS is purely a product of using malt, so won’t be an issue here. If the sulfur persists, racking your cider to secondary through a short piece of copper tubing does wonders.

Thanks guys. It’s already smelling less like sulfur. The house got colder last night, and with the ice packs I threw in before heading to bed, I got the temperature down to 54 degrees by this morning. It’s still got a steady bubble in the airlock. Funny how when I started brewing beer I thought yeast needed heat and used a heating pad around the carboys. Boy, what was I thinking!?!