Squado, make sure your output hose isn't too deep in the bubble box - if you block the flow in there at all, it'll force water higher towards the collection cup and kill the ability to get good skimmate. Try removing your bubble box entirely, and see if you can get a good setting. Then add it back. You might have to trim the hose that drops into the bubble box, I did at first.
I don't even use a bubble box anymore - but I'm using mine in a sump. No bubble problem at all.
180G build thread
180G All-glass with dual megaflows in a custom stand
AquaC EV-180 skimmer
250 pounds LR
160 pounds aragonite
Custom acrylic sump from GlassCages.com
2xPCX-40 return pumps
2x250MH 14K, 2x175MH 14K - PFO lighting, 2x65W PC
No-name 36W UV
Water General 125GPH RO/DI