Sounds like you have a failing sump design.
It should go like this:
1. mech first to catch all your crap.
2. bio to help the nitrogen cycle.
3. return.
From what I have read ^ the sump set up has crap trickling down clogging your bio media, then you want to use mech before the return. This does not make sense.
You said you would be "open to all suggestions".
My suggestion is to redo your sump design. Heck sketch it and throw it on here so we can help you.
By the way sera siporax > matrix bio media > eheim substrate pro > jbl micro mec
Bomber