I'm not framiliar with that particular skimmer but I actually tried to find a pic of a seaclone 150 with google and all I could find were hang on back models. Is there a in-sump design? If your talking about this, I don't think it would work very well in a sump if at all.
http://www.aquatichouse.com/Protein Skimmers_files/seaclone150.jpg
I could be wrong, there may also be an in sump model, or it might be somehow convertable???
Anyway,
in general, the main issue with sump mount skimmers is that the water level be consistent. When skimmers are located in the sump and the water level fluxuates (no auto top off or seperate skimmer compartment) then it becomes very difficult / impossible to maintain a steady level IN the skimmer and thus you get erratic / poor skimmer performance.
If the skimmer has a somewhat low outlet point (for example PM bullet skimmers have outputs only 6" or so off the bottom) you can raise the skimmer to idealize both skimmer performance and sump depth (assuming you have the space).
I use a PM bullet and have it set up behind the display/sump and raised so that the output sits just above the top of the sump and into a pipe/bubble trap. This way I can keep the water level in the sump pretty deep to reduce microbubbles + add volume, and the skimmer doesn't have to fit under the tank.
Hope some of this is helpful?
Do you already have the skimmer and what size system do you have?
jk