I feel that my sump could be made a lot more efficient. I have never changed the configuration - it is the same way I bought it. Here is a diagram of my setup:  
 
The overflow from the DT (actually from a secondary sump housing the skimmer - my skimmer couldn't fit under my tank where the main sump is) comes into the right hand side of the sump through a prefilter (scourer pad) and wet-dry trickle filter. The right hand section contains some scrubbies. The water goes under the first glass panel and into the middle section. Here there are 3 containers of ceramic noodles and crushed coral. The water then overflows into the left hand section where it is pumped back to the DT. 
 
I want to make this more efficient without having to add or remove glass - I am not confident with glass cutting and am pretty poor. 
I thought I could move the bionoodle/crushed coral containers into the right hand section - there is plenty of space under the floating scrubbies. Then I could turn the middle section into a refugium, however the middle is only 17cm long, 26cm deep, 30cm wide. 
 
Any other ideas? 
 
Maybe you could post some plans of your sumps to give me ideas?