There's alot of opinions on flitration and turnover, but at the end of the day in a large planted, high-tech tank the filter will eventually become mostly a flow device and most of the 'filtration' will take place in the tank, both with the plants, substrate and the water changes that you'll be doing weekly in that type of setup.
I've run tanks for years with 1-2x effective turnover and no powerheads nothing wrong with more, but probably not necessary. The 72G in my sig is an example of one. It had one eheim 2215 with no powerheads. I also used a simple ceramic disc for co2, which is what ADA does on even their largest tanks.