Each category of corals is different. Soft corals have different needs than large polyp corals and small polyp corals are different yet. Also, individual subcategories of corals has its own needs. In SPS corals, you have birds nests, montipora, pocillipora, acropora and others. Acropora tend to be the most sensitive. But some are far more tolerant than others. So you need to read up on the category of corals you wish to deal with and often read up on the specific group in the category. Even then, you will find conflicting accounts. I suspect that there are many interacting variables going on in each tank. Two tanks can seem to be very similar in nutrients, flow, lighting, ALK, CA and Mg but one will have flourishing corals while the other quickly kills them.
