We did this with fish and came up with a solution that most likely will not sit well with people on this site.
Air stones really do not allow the air to absorb well into the water. More air can be absorbed by surface agitation of falling water then air stones them self to say. If you dont have a lot of water falling into it them, yes the air stones are going to crate the surface water movement that you need for the air to get absorbed into the water. So in theory the more you can brake up the water the more it will become enriched with air. However i also believe that water can only hold 11 parts of oxygen, and no more. Thats why the have the foggers out there for hydroponics, because it will be 100% humidity and 100% air.
I hope this helps your thinking.
- smurf
some videos
http://www.youtube.com/watch?v=4oAQh8kH94E
http://www.youtube.com/watch?v=KTzzJV0UTvs