First, what do you mean when you say bubbleponics? To most people it means a hydro system with airstones. But if you mean the kit Stealth Hydro sells that adds a water pump and feeder tubes (unnecessary IMO). Anyway, it's a matter of rootspace and you could grow 2 large plants in an 8 gallon tank. I would want one a bit larger like maybe a 14, but not just with added depth - with more surface area to let them spread out. I'm building a new DWC box (with lots of bubbles but no tubes) and I plan to grow 5 plants in it that could easily go 4 ft. What other "specs" were you looking for?