It is much better to have the skimmer sitting in the sump with a pump tuned for the output of the skimmer, placing the skimmer high enough so that any fluctuations in sump depth will not affect the skimmer foam column height.
precisley. skimmers are designed (to my knoweledge) for a specific GPH wich can only be acurattley administirred by a pump included with the skimmer or a pump reccomended by the skimmer manufacturer/ LFS that will suit the perticular model and aplacation. For example, if i ripped the air line off the maxi on my
bak pak, and had a mag 3 feed water into the skimmer, it would overflow because it was designed for the aprx: 250 gph that the maxi provides.