hi mark
i have recently gone against the flow and got a prizm
100gallon model cheap to replace an air driven
skimmer i was using
in my nano. the water line is 2" below on my setup and it skims great dark and dry i think the 4" stated in the user manual is a maximum rather than a recomended water level, many people use them in
sump as this makes them much less noisy the person i got mine off used it in
sump on his setup
