pH, nitrate, ammonia is enough to get by for a brand new tank with no sps corals. If you want to work proactively to prevent algae check Phoshate if you aren't worried about algae then don't worry about it. If you get into SPS or LPS corals then you need to start buying the calcium, Alk and mag. Someone please correct me I'm always wrong on here. All I know is that before starting crazy cool corals the pH ammonia and nitrate was enough for me to get by. Ammonia is #1 killer of fish in new tanks so I think that's important.