Air lock water level dropping

Hi,
I have a fermenter in a temp controlled freezer at 65F, on day 3. Each day the water level in the air lock has dropped from the max fill line almost to the bottom, I refill it at night. I'm on I guess my 11th batch of beer, and have not seen this before. Any thoughts on what could be causing it? I checked the airlock for leaks, doesn't appear to have any. Probably unrelated but there is no activity in the fermenter either, bubbling etc but I'm giving it more time.

I'm using the airlock type where it has 3 pieces including the cap, not the S lock.

Thanks!
Rob

Are you getting suck back? As long as it is sanitized (vodka or starsan solution for example) it shouldn't matter.

Sometimes I get it initially when fermentation is first starting but once it is rolling it should maintain a positive pressure.

Yeah, I get it almost always on day 1-2 of fermentation, then it stabilizes.

sounds like suckback. As the wort volume condenses via chilling it displaces the water in the airlock until it stabilizes.

Your beer is trying to drink you!!! (insert creepy psycho music)

I had it happen and pulled the airlock off and replaced it after a minute or so and refilled it (after a few spritzes of starsan on the grommet and airlock stem).

ok, thanks for the explanations on suckback, I hadn't known about that before.

Thanks! Rob

Because of suckback, I always replace the 3-piece lock with an s-type lock after the fermentation slows, since those will refuse to suck back the liquid if you don't fill it too full.