What size Skimmer for a 55gal tank??? Help me

[Gsxkid]

I want to build a skimmer for my 55 gal tank and was looking for some help . I made one of those air stone ones for my 20 gal tank it worked alright but i wasnt to impressed. I have been reading all the threads and see another type of skimmer. It looks like they take a pump and put a hole before the inlet and allow air to be sucked in to create venturi. Is that what they use for bubbles ??? I dont want to big of a skimmer because i want it to fit in the sump that i am making. Any help is appreciated, Thanks