They're already after all mechanical filtration and the skimmer. I do have a filter pad after the fuge, but thats mostly to keep loose bits of chaeto from circulating. I'll see if I can move them a bit down stream though.Ok, I understand your setup more now. My only suggestion would be to move those plates out of the first compartment and closer to the return pump... after all mechanical filtration and even after the skimmer. They will still experience a lot of flow over, through, and around them but they will take less abuse and potential for sedimentation. Should make them more effective actually.
Skimz have great products and if the price is close to Jebao might be worth a shot. I've haven't used their circulation pumps but really loved the Skimmer I had a couple years back. The Jebao pumps are certainly fine, but you have to make sure to clean them often (monthly). They lose a lot of power when they get dirty (moreso than Tunze, for example) and this may also lead to shorter life span. I assume their more recent models are better so why not give them a try.
The skimz are one I've been leaning towards as a great value ($120 per pump) mostly because I've heard good things about the brand. My only real concern on them is that the flow might be too broad for how I'm looking to use them (mounted low pointed from overflow towards returns) given the general design, which is all I really have to go off of. Jebao or Rossmont appear like a better design for a tighter flow (or go Tunze for a lot more $$$) and are both a bit cheaper at $105 and $87 per pump
Also a consideration although I'm not entirely sure my skimmer is efficient enough to get the most benefit out of it. If I go that route, I might try a liquid carbon source first to see if I start pulling crud out like I should since that would have a quicker and cheaper start up.If growing cheato is working out, look into running a biopellet reactor.
I am planning on building a second skimmer with a recirculating design with the other 5' of 6" PVC I have left over from the first build. That might eliminate some of the efficiency concerns.