For a becket
IMO after do a lot of search built a lot of them and test, the best skimmer for pure skimming power are the Areofoamer! for a 500 a model 830 30 inch tall by 8 inch OD rated for 100-1000 gallon if money is not a concern buy this puppy you will not regret it
http://www.reefconcepts.com/products...ers/800series/
Here is my version I made it cause for me money was a concern but I want the top!
http://zapzap.zwf.net/gallery/Album-de-stephane?&page=4