Uh there is nothing like fresh water especially for fish. I haven't really seen to many systems, especially hi-tech that don't rely on the water change it's for me an no-brainer. The difference between doing a water change and not doing one is this. If you do a regular large water changes and dose back in you are in a preventive mode, stopping anything before it starts. Sure some tanks with high plant mass, low stock can get by with few water changes, but why guess where that balance is. As long as you dose back in your removing waste. When a tank is new, there is no bio-filter so carbon for example acts as a bridge removing waste before the bio-filter (plants/media) gets established. Large water changes also allow alot more wiggle room with light, stock and plant load. Not every tank is filled with plants. In scaping there is alot of negative space, especially in an iwagumi type setup.