The big max offer you show is a rebuilt unit and only lasts a year before they need rebuilt. This is based upon me and my neighbor's experiences over a couple years. My last rebuild resulted in stripped threads on the housing bolts. Never again.

Agree about the non-weighted airline comment above as well.

I am getting much better aeration from the top-of-the-line Hiblow long lasting compressor and it is so quiet you can barely hear it at all unless you are standing right above its shelter. I've got two 2"x2"x12" airstones connected to it and it is simply outstanding. I run it all year long, non-stop. Easy filter access and cleaning. Always put check valves near your diffuser heads.

Cheers

Buckeyedude