Coral metabolism vs. light par

[BlueAbyss]

More zoothanthellae = browner corals. Corals have other pigments that are easily masked by the brown zoothanthellae, which is why corals under higher light tend to be more colorful. Nutrients will affect the color also (food for the zoothanthellae), as will feeding (food for the coral). If you have an ultra low nutrient system (like zeo), you need to feed your corals to get the most out of them... hence zeo's clam and coral food.