For a setup like this water changes are your friend. This is the basis for 95% of reef tanks and most only add a few more pieces of equipment like a reactor for GFO(phosphate removal) and Auto top off to keep from having to manually fill the evap water.
I would highly recommend getting an auto top off just to make your life a little easier. As your tank sits now as long as you keep up with your water changes it is perfectly suitable as a reef tank, taking into consideration that you have the correct lighting for a reef tank.
The KISS method (Keep it simple stupid) is often the easiest way to keep a tank because there's less for there to go wrong.
Good luck!