HCA: Hermit Crab Association

What's a good brand airpump for my humidifier that won't hum and buzz on my hood?

I think it's Whisper that has one that's on little feet. If it costs more than the other ones it's only by a couple of dollars at most. The feet really really help cut down on the noise. Alternately, you can fold up and place a teeshirt under the one you already have. Ugly, but it does cut down on the vibration noise.

I've wrapped my aquarium air pump in a towel for years and have never had a problem. That doesn't guarantee that it isn't a hazard, but it doesn't seem to be a big one.

The whisper is one of the quietest ones, in terms of internal noise.But don't be fooled by any fancy feet, it will still cause vibrations to echo throughout the tank. The wooden tank stand turns into a subwoofer.But no fear, there are solutions, as mentioned. I just placed a folded towel under the pump, and this is sufficent to dampen the vibrations enough so it doesn't cause the whole wooden tank stand to vibrated.Then you have to take care of the plastic tubing coming out of the pump itself. The plastic tubing is vibrating pretty well for the first foot or so. If it contacts anything, you'll hear a high buzz as the tube is vibrating against another object. Usually just manually adjusting the path is enough to prevent extra vibrations.