Huh - go figure - I had figured that all multiple pump skimmer designs were recirculation style. I.e, the pump draws water from the skimmer body and the water feed to the skimmer itself is independent of the needlewheel (meshwheel now) pumps.
I had to mod my ASM to be recirculation, basically all I did was drill a new 1.75" hole (the 1" uniseal requires a 1.75" hole same as for a 1" bulkhead) and hooked the pump in that way. For the last year I've been feeding the skimmer via a T off the overflows, now I'm feeding with a maxijet 600 (after trying a maxijet 1200 for the last week). I read on asmskimmer.com/octopusskimmer.com that for a recirc skimmer you want a feed pump about 1.5 times your tank volume (but I'm not sure if that number is just a WAG on their part - I don't know if there are any metrics applied to generate that factor value of 1.5).
Seems to me you might need to think about modding the skimmer itself. The problem is that the pumps are just pushing too much volume of the air/water mixture for the exit pipe to carry out fast enough. You could start by trying to raise the skimmer so that there is a larger height differential, but it sounds to me if you're racing water through the skimmer that it doesn't have a lot of contact time. So going towards a recirc mod on your skimmer might be something to look at.
I'm not sure what I'd do. Bear in mind this is all black magic to me, so don't just follow MY advice because I'm clueless!!
