Here's a design I used for my last 55g sump (for my 155g tank) and I loved it, but there was 1 issue; I made the skimmer zone too small, so it could only house the skimmer pump (not the UV
pump or phosban reactor pump). Plus the waterflow from the skimmer zone to the refugium was too fast, so all the sand and macro algae was spinning in circles.
This is from Melev's Reef:
If I could find a way to utilize the space better (limited because it's a 55g tall tank), and reduce the flow so that I could actually use the refugium zone, I think this would work.