Some new info:
I use the duel diaphragm air pump from General Hydroponics. If you have a pump like this, it would be a good idea to keep a rebuild kit handy. Or a spare pump. Mine just went out (hole in the diaphram).
The kits cost $20. You can get them for $12 at
http://www.wormsway.com .
I have two pumps like this and both need a rebuild after less then 8 months of use.
I think I would rather go with a high output pump like the eco-plus or durapump from Sunleaves. The rebuild kit is only $1.95
This pump puts out more air and is half the price. I just don't know how loud the are.