get a custom made tank, with lots of EXCESS and ACCESS.
Factors in lots of FLOW rate, give it abit of extra height, extra width and also extra length. Maybe can have 2 sump tank instead of one so you can add in 2 sets of equipments. Can be quite costly , but depending on how u "want" this hobby to be.
I intend to get one 6ft tank, hopeful this year, 2 sump tank. then can try out various Needlewheel Side by side. Hns and Deltec to compare... and also the very correct design in the first place can save lots of extra work.
My current tank is a 3ft*3ft*26inch tank. Werid combination rite..with lots of constraints for wiring, and lightings..have to "think out of the box" and allows creative to set in..but ofcoz at a risk..thus also deploying alot of expensive equipments for the wave. 2tunze, 2 maxis (on the way) and one seio with ocr6500.
Get a well design tank, Good Return Pump then get one or two Wavebox can liao..
Overkill is better than under...try not to save and get lots of problem later..
2cents