I have a 120G display with about 30G more in sump.
Run both an Omega 150 with a Vertex Vectra neck cleaner and a Skimz SK181
The Skimz has about 9" of water, Vertex is lifted to about 6.5"
Biopellets piped right into Skimz skimmer, it pulls out decent sludge/waste
Vertex is right next to my drain pipe, it pulls out the darkest, nastiest crudd
venturi is turned in all the way. I found it was a bugger to get figured out but also found that small adjustments over long periods of time was best for getting it going good