I run a pretty simple system. I do use mesh socks but still am getting a nice build up of mulm starting because I tend to let them overflow for a day or so before I change them. Tank has only been running since March. I've never cleaned a sump on any tank. When I tore down my last tank I scooped all the sump nastiness from 7 years and dumped in the sump of the new build. It was full of life.
Rock is from the last tank. Display was started with all dry rock. It's run as a cryptic fuge so no light.
DT
For disclosure I do currently have a skimmer running skimming very dry when I remember to turn it back on after feeding. After I started running it I found out the smart timer for the scrubber LEDs got dumb and wasn't turning them on. After fixing that and adding the skimmer my PO4 went from 0.68 to 0.27. I'm about ready to shut the skimmer down and see how things go.
EDIT :
@VintageReefer was a big help in my decision to run this tank using these methods.