Actually, I've seen a few really good diy filters where an air bubbler would work great for a saltwater tank. The one that pops out the most is a fluidized bed filter design I saw here on the forum. I would just switch out the fluidized media with refugium rubble and call it a day. I'm going to keep one running for qt purposes.
The media is enclosed within a bottle with holes drilled on the sides to keep the media in. 0 salt creep and highly oxygenated water for the tank.
Mebbid's Fishtopia: Various builds
"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations." -Occam's razor