Now that makes sence. I was out thinking about this today, and I think maybe you have the best idea after all. I want my skimmer on the 120 to be overflow driven, no pump at all. I think a beckett or venturi would add to much head for the overflow and may back it up back into the tank. Maybe going counter current then the lower output going co-current would be the way to go. I could go without an extra pump just using the overflow from the main tank and still run two smaller skimmers.
I still think it would be much better to have to different "technology" skimmers as opposed to just one, I'm considering counter and co-current skimmers the same tech. I wonder if a small powerhead between the two would be enough to go from the counter current output into a beckett style?
Let me know what you come up with, and post some designs. I'm not ready for the skimmer but its certainly never to early to start thinking about it. I understand wanting to use a smaller pump, I don't want to use one at all in my design. Why generate the heat if we don't need to right?