The skimmer is in 9 inches of water but it is actually a Curve 7, this tank is a recent upgrade from my old 120 gallon tank and I just kept the skimmer. I may upgrade it later once I stock the new tank heavier but the whole Covid situation has led to a fish shortage in my area so I barely have enough fish in the tank right now to get detectable nutrients. I’m actually only running the skimmer 12 hours per day at the moment.Very nice setup. By the way you have a bubble magus curve 9 i think which is what im putting in mine, how high do you have yours in your sump?