I have an rsk 300, i think it's a bit too big for my bioload in my 75. If i run it intermittently it skims great, but is kinda hard to dial in if i run constant. I love the drain hose and neck window though. I would weigh in more but this is the only skimmer I've ever had.
Fish load:
1 Juvie yellow eye kohl tang
1 Juvie scopas tang
3 Mature pajama cardinal
3 blue green chromis
1 mature fire fish
1 2.5 inch green halichoeris wrasse
1 ocellaris clown