They are in sump, here is what I have
Vorbereitung für Wasserstand > 200mm:
Master DOC Skimmer 9420: Wasserstand bis 370mm, 1 x Hydrofoamer, Ausgangsrohr 230mm
Master DOC Skimmer 9440: Wasserstand bis 270mm, 2 x Hydrofoamer, Ausgangsrohr 120mm
Master DOC Skimmer 9460: Wasserstand bis 410mm, 3 x Hydrofoamer, 2 x Ausgangsrohr 280mm
Master DOC Skimmer 9480: Wasserstand bis 370mm, 4 x Hydrofoamer, 2 x Ausgangsrohr 240mm
The 9420 and 9440 will need an 18" sump but this could be reduced as the skimmer will include a kit to hook up the pump with a hose that I have not seen yet. It is 23" high
The 9460 and 9480 will need a 24" sump but the same kit will be included. It is 28" high. An additional 6" will be required to remove the cup.