Coral Coloration: Bringing out the best in your corals.
It's no secret that coral can change colors (within reason), from one aquarium to the next. What can be confusing is why that happens. In some cases it isn't the coral that is changing but the way it looks under certain lighting. Other times the shades change and new colors even emerge. We're going to explore why that is and what you can do to bring out the best coloration possible in your coral. I'd like to say we're helping the coral live it's best life, but who am I kidding? You're the one staring through the glass so maybe it's you living your best life.
What is Zooxanthellae
Why do I need to know about zooxanthellae? Zooxanthellae are actually a photosynthetic dinoflagellate that lives in the coral tissue. At it's most basic, zooxanthellae provide protection and food in exchange for protection and food. Sounds odd when put like that of course.
Corals provide safety and nutrients which enables the zooxanthellae to carry out photosynthesis. In return the zooxanthellae pass on oxygen and other nutrients as well as a protective layer that protects the coral from light and other harmful factors. This protective layer is what gives coral it's often times unique and beautiful color. It's your job to protect both the coral and zooxanthellae if you want your own crazy colored reef.
Nutrients your coral needs
First and foremost we have to mention stability. You will hear this a million times, above all else you need to focus on stability. Getting your numbers where they need to be is all good and well, constantly changing or adjusting things to be ultra specific is usually not. Nitrates and phosphates are an essential part of all life, including your reef aquarium. Without these nutrients life would not exist; and much like my love for steak, moderation is key.
When nitrates in your aquarium get too high it can shock your latest coral addition, slow down coral growth, and give an abundance of food to spread algae across everything.
Similarly phosphates when too high will cause issues as well. Mainly by limiting a corals ability to absorb calcium from the water to build new skeleton and feeding brown algae within the coral tissue. This results in weaker growth, higher susceptibility to damage/death, and colors being washed out.
Phosphate .02-.10 ppm
Nitrate 2-10 ppm
Staying within these ranges is widely considered to be the goal. If you're nutrients aren't quite there and you are working on it I suggest focusing on nutrient export versus feeding less. I will touch on this more in a later post.
Coral lights bring out color
You've probably already noticed every reef tank you've seen has blue lights over it. The blue lighting serves many purposes but for the moment we're going to talk strictly about color. Different brands of coral lights and different settings even can change our perception of how colors look. This is why some times you'll notice a new coral you've brought home doesn't look quite the same as it did before. Nothing has changed with the coral, it's how your lights make it look to your eyes. This isn't a bad thing and is fixable if it matters enough to you.
Actual changes in color however are different. The zooxanthellae we mentioned before produce pigment that gives coral it's color. Depending on light intensity zooxanthellae adjusts the pigment to protect itself, and subsequently the coral, from the sun. Or in our case, our lights. Think about a bright glowing coral being the equivalent of our having a suntan. In a basic sense, the more intense the light the more colorful the coral. Bear in mind that to much light will also kill a coral. The zooxanthellae can only tolerate and adjust pigment so much before it's limits are reached.