Another vote for the AquaMedic TFs. I have the 72" Single, and it works GREAT. They are a little different than the becket type or veturi type skimmers. The pump needed to feed water to the skimmer is a small GPH compared to the size of the skimmer (1000 gph for the huge one Mike & I have). The skimmers come with another pump (or two) connected to the skimmer in a closed loop configuration. All the agitation & bubbles come from the closed loop pump. Contact time in the skimmer reaction chamber is better than any skimmer I have ever seen.

They sell smaller versions TF "baby" & "Shortie" for in-sump applications.

They aren't cheap, but you also don't need an expensive high GPH pump to feed them.