New setup skimmer overflowing week 6

[zv3n]

Hi, i recently started a new setup using a small amount of my old live rock from my cube and 80% marco rock, i have a swc 250a1 cone that has been overflowing since day 1. I tried letting it overflow in 5g bucket for 20 gallon to try and remove whatever is in the water. I haven't used chemicals or epoxy.
Skimmer is sitting in 6.5" of water valve is fully open I'm not new to this so i was curious to know if any one has experienced this.

When i replace the water that i skim out (5g x 4 times now) it settles for 45 min but then its starts overflowing again!

Any ideA's?
Thanks