Overall, in our opinion, not much.
Still fish and corals in a glass (or acrylic) box filled with water. For the animals to survive and thrive, the goal is “clean”, balanced saltwater and the strategy as we see it remains the same, water changes.
The frequency and amount of change depends on your bio-load, your acceptable loss policy, and budget (time and money).
For us, the sweet spot was 10 to 20%, every week or two.