I don't like to use check valves because they reduce air flow, sometimes by quite a bit. I like to put my air pumps above the res and that solves any back flow issues.

Did you see this one?
http://boards.cannabis.com/hydroponi...bles-once.html
Opie Yutts Reviewed by Opie Yutts on . Koi Pond Aquarium Air Pump Koi Pond Aquarium Air Pump It looks like it would work well for multiple DWC buckets, does has anyone used this? Also has a 12 outlet manifold so you could do 6 5 gallon buckets pretty easily correct. Is there any reason not to use this? Thanks for the input. Rating: 5