That design is the flow through design. He opted for that design. IMO, its a good design. But there is also the flow to center design. Which is a good design. The choice is yours to make. I can help you with either. Heres my take.
Flow through design.
This design allows for larger compartments with fewer baffles involved. Flow is greater as it all flows in one direction through the compartments. Cheato likes to tumble so flow is not an issue. Debrtious fall out is ppossibly not as great over sandbed, as the flow is faster. However by providing a LRR chamber prior to the fuge debritous collects there to be processed. Also, I have found the flow to be fine with the large fuge chamber and depth the fuge first design this style provides. Because the fuge is before the skimmer, there is the likelenss that pods will be skimmed out as they pass through the skimmer compartment. However this can easily be compensated for by providing another additional LRR pile after the skimmer. Blowby will be increased in both compartments as thr flow is greater. However I dont think its really an issue as nutrients will be returned at some point to be processed.
Flow to Center
This design allows for slower flow as well as greater control of the flow through the fuge compartment. Though the compartments, in order to get good bubble elimination, are smaller. With more baffles involved. While some of the baffles can be eliminated as I would design one. I believe that they are of great benefit. Blowby is less of a factor as the flow is slower allowing more time for macros to process nutirients. However if cheato is your preferance, then additional flow may be necessary in order for it to tumble.
Thats the basics of my take on both designs there are adaptations that can be made to either design. If you know what it is you want to include we can design around it. Things like heaters, an auto top off, mechanic filtration etc can and should be provided for during the design. Have you thought of how your going to handle these things? Consider using a couple if not even 3 phosban reactors. You can plumb for these while doing your return pipe plumbing. As well as a place to put a sponge between baffles for mechanical filtration. I think the fluval large sponges fit well in a 55. Measure your sump and go searching for something that will fit depth wise. We'll pick a baffle set to place it in between. Also if your going to use a UV, it can be plumbed into the return also.
BTW, heres a basic flow through design plumbing.
