Water changes will help a little; maintaining a good filtration setup (including a refugium) will do more in the long run. A good cleaning crew can also make a big difference.
You either deal with the nutrients in the tank, ways to export them or some combination thereof. Take my 200-gallon system.
* 4x 100-micron filter socks; changed every 2 days
* Protein skimmer; emptied every 3-4 days
* 2.0L Zeo reactor, 1.0L Carbon/GFO reactor, 57-watt UV sterilizer; 2.5ml of Zero daily
* 2x MarinePure 8x8x4" bio bricks, 2x boxes of 1.5" spheres
* 100+ member cleaning crew and a half dozen "helper" fish that perform specific duties