I've always wondered how to maximize the contact time in a skimmer, without having to go verticle.
Everybody seems stuck on a long tube to use as the main body.
An idea has always stuck in my head to build a skimmer in the shape of a rectangle with baffles.
A beckett type injection could be used to supply water and air in.
Then the mixture could flow up and down a series of baffles, ala bubble traps. If the downdraft portion of the baffles where tight enough to provide enough velocity to also drive the bubble to the exit, it'll naturally rise in the updraft section. This could be repeated over again, until there is a size limitation. The last section would have to contain a funnel to skim the sludge.
Simple conceptual drawing...
thoughts?....