I feel it is very important to thoroughly mechanically filter the water prior to putting it through Bio Media. Solid waste has the potential to clog pores thus making Bio Media far less efficient.
 
Personally, I would have thorough mechanical filtration in the first couple of chambers, then spill over onto a drip tray to be spread over the Bio Media…
 
Your design appears to leave a very large area in the middle that is unused. Therefore you should have plenty of room to shift your Bio Media chamber to the right and put mechanical filtration to the far left…
 
Also, have you considered planting the empty section in the middle? I’ve made a sump design recently and I’ve chosen to make a section that has java moss in a large egg crate / plastic screen cube. This will prevent the java moss from getting tangled up in the pump or clogging it’s intake.