Gonna need a bit more info, like how many watts of lighting and what kind do you have now. Also need to know what type of corals you want to keep? Type of corals will really tell you what type of equipment you want.
You're most likely going to want more than just the return for water flow. It's hard to set up currents that your corals will like with just one water source. The return plus at least 2, maybe 3, powerheads will most likely give you adequate flow. For a 75g tank, you're looking for a combined flow somewhere in the 1200+ gallons/hour range.
You're also probably going to want more rock. Looks a little spare in there, and the more rock you have, the more real estate for the corals!