I had a super reef octopus xp3000 on a medium stocked 180, and it kicked butt!!..I have nothing against reef octopus skimmers, I actually recommend them all the time. With that being said, your skimmer is not skimming correctly. May not be the skimmers fault, but u need to correct that first.
I currently have a similar sized bubble king on my medium stocked 250g tank (100g sump). When I was running BPs, my collection cup would be completely full in 5-7 days. Your skimmer should have a LOT more skimmate after 3 days. I still think the skimmer is a big culprit. Do u happen to have any other skimmers you can borrow? Something that you know will skim efficiently. Give it a test and let it run for a week or two. Even if it's an under sized skimmer, I think that's ok...you just need something to pull out that bacteria. Something is wrong with that skimmer
Does the water level fluctuate in your sump? My reef octopus was super finicky if the water level changed in my sump.