Yes.
I ran this exact same skimmer in my reefer and it was in sump.
Nice thing about the externals is that they aren’t picky about water level.
Just feed it with a pump in the sump, or tee it off of your return. I’d shoot for 400-600 gph. Then you use the gate valve to adjust the height in the skimmer
You can then use the plumbing that came with it to discharge under the waterline. Just remember to use the vertical vent pipe if you do discharge under the water. Otherwise it creates a slight siphon effect. But if the outlet pipe is only partially submerged then you should be ok without it.