UPDATE Jan 2, 2019
Plywood cut layouts have been done and redone many times lol. Wanted to use the full 4x8' sheets as the base but carpenter mentioned that 1/2" should be trimmed off each edge of the plywood to ensure clean cut edges. So will have to live with a ~700 gallon rather than 720 gallon, nbd lol.
Also going back and forth about whether to do internal bracing or not. Decided to use the extra plywood and do a single strip of 2" inside corner bracing.
Regarding the sump, got a lot of good feedback in my other sump thread and will likely go with the above design minus the last two baffles.
Still debating how much flow to use. Have been recommended 10x turnover by many but have also had some people mention that 10x would be too fast for any beneficial bacteria to grow on submerged media. Any thoughts on this ?
Regarding over flow, still deciding between an internal acrylic coast to coast ish overflow vs plywood external overflow. Still be doing a bean animal style overflow with 2 x 2" siphons, 1x2" Durso, 1x2" emergency drain. Is this enough to handle 7000 gph of flow?