They grow corals fine despite not producing as much light as other T5 fixtures. The reduced light output comes from the bulbs being spaced close together and the reflectors are flat causing re-strike. This doesn't mean they won't grow corals, but they do produce less light per bulb. In a shallow tank it's no big loss. In a deep tank it can be a real issue. If you're trying to grow soft and LPS
corals in a reasonably shallow tank the Odyssea lights will give out all the light for coral growth most people need.