I don't you guys understand how a wet/dry works if you are worried about contact time and large waste loads. The efficiency of wet/dry filtration is much greater than that of any other save, perhaps, fluidized bed filtration (which comes with a whole host of issues). Given the same amount of media space, a wet/dry will easily outperform any typical submerged application, and that applies to degassing, oxygenation, as well as nitrification.
I think the confusion when one sees both bioballs and ceramics in use applies to the type of filtration in use. Many Europeans use sump filters that actualy completely submerge all the media. In that case, rings, gravel, sponges, and a host of media is used (and bioballs would be a less than ideal choice in such a case). Over here in the USA, sump filtration seems to equate to wet/dry filtration only, so bioballs are usually the choice.
By the way, I'm one of "those guys" with a 1000 gallon tank!
I think the confusion when one sees both bioballs and ceramics in use applies to the type of filtration in use. Many Europeans use sump filters that actualy completely submerge all the media. In that case, rings, gravel, sponges, and a host of media is used (and bioballs would be a less than ideal choice in such a case). Over here in the USA, sump filtration seems to equate to wet/dry filtration only, so bioballs are usually the choice.
By the way, I'm one of "those guys" with a 1000 gallon tank!