As far as the water pressure fluctuating between them, I don't have that problem. I have a sequence hammerhead with a branch as my return a bypass back to the sump and two take offs for the MR3. Each arm has its own ball valve. The skimmer take off it first, followed by the by pass and then the return. I basically leave the skimmer valves wide open, I then left the by pass wide open and shut won the flow to my tank to a point that had the water level more or less where i wanted it, I thenclosed the bypass off a bit to add a bit of pressure to the system Every thing seems to be very stable. The water level in my tank remains constant as it does in my skimmer. The water level in the tank goes up slightly when i shut down the becketts for cleaning, but its minimal (suggest you make sure your overflow can handle the increased flow the first time you try this.. no problem in my case).
How much flow/pressure is a beckett supposed to get?