Sump Questions

[ickmagnet]

So I have a 55g ( I think ) glass aquarium that I will be using as a sump for my tank. It is 36" l x 18" w. I plan on making it fairly basic with the protein skimmer and overflow return in the same chamber. Just a quick question; How high do the bubble trap baffles have to be and how far should I space them apart? Should they just be a few inches shorter than the height of the tank? I'm hearing everything from 1/2 the height of the tank to 3/4 height of the tank to a few inches less than height of the tank Also, should I space them about an inch apart from each other?

Thanks