One of the most exciting things about owning a reef aquarium is the satisfaction of growing coral. Not only is it satisfying, but it is also good for the environment as well as your wallet. The bragging rights for having large, colorful corals aren’t bad either.
So how do you maximize coral growth and coloration for your coral? Corals are complex organisms that require the right combination of light, food, nutrients, water flow, and water stability to thrive. Today, we’ll discuss how to provide them with these essential needs.
Lighting (Intensity and Spectrum)
Most corals kept in aquariums are photosynthetic and rely on light for a considerable portion of their energy needs. Symbiotic algae that live within the coral polyps use sunlight to make sugar for energy. This energy is then transferred to the polyp, providing it with much-needed nourishment. In exchange, the coral polyps provide the algae with carbon dioxide and a protective home.
Efficient photosynthesis requires not only adequate light intensity but also the correct spectrum of light. Terrestrial plants, like those found in our garden, favor colors in the yellow, orange, and red range while corals favor colors in the blue spectrum. As water depth increases, the reds, oranges, and yellows are gradually filtered out, leaving more blue light. For optimal coral growth, you will generally want a full spectrum of light that includes some reds, oranges, and yellows, but that is heavier towards the blue range.
There is a current trend in the hobby towards very blue, nearly dark aquariums, with glowing corals. While many believe this looks good, it is still essential to provide a full spectrum of light for improved growth and coloration. If you like lots of blue, we recommend running a fuller spectrum of light for a few while you are out and transitioning to a bluer range when you are home enjoying your tank.
To learn more about intensity requirements, please read the following article: https://www.atinorthamerica.com/blog/what-is-par-and-how-much-do-i-need/
In addition to photosynthesis, corals are great hunters and eat by catching tiny floating animals called zooplankton. This “hunting” usually occurs when the sun is down and the tiny crustaceans are out.
Corals also need nutrients, like nitrate and phosphate, for optimal coral growth and coloration. It is crucial to maintain these nutrients in the appropriate range without too much or too little. Excessive nutrients levels will cause algae growth within the coral tissue causing it to turn brown. On the flip side, insufficient nutrients levels can cause the algae to die and corals to lose color. To maintain the correct levels, we recommend frequent testing of phosphate and nitrate. We also recommend periodic ICP laboratory testing with our ICP-OES Water Analysis to check the validity and accuracy of your over the counter tests.
To learn more about nutrient dosing, please read the following article: https://www.atinorthamerica.com/blog/how-do-i-optimize-drive-growth-with-ati-nutrition/
In addition to nutrients, elements are also important to maximize coral growth. In the ocean, calcium, alkalinity, magnesium, and other essential elements are steady and consistent. Maintaining this same level of consistency in your home aquarium is an absolute must for growth and coloration. As an example, excessive or inadequate alkalinity is one of the fastest killers of corals.
To learn more about essential elements in a reef tank, please read the following article: https://www.atinorthamerica.com/blog/water-quality-for-reef-tanks-part-3-the-most-important-additives-supplements/
Corals don’t breathe or poop in the traditional sense and require sufficient water flow for respiration and waste removal. Proper water flow brings in fresh oxygen and helps flush away waste. Just like lighting requirements, different corals have different water flow requirements. Soft corals without a stony structure require the least amount of flow, while SPS or Small Polyp Stony corals require the highest water flow. Water flow also needs to be both random and indirect. Corals don’t do well with a water jet blasting directly into them. Instead, they prefer a varied flow pattern with water coming from different directions at different times and with different intensities.
Keeping corals is a challenge, and to maximize coral growth is an even greater challenge! Growing very brilliantly colored corals is a greater challenge still. Keeping proper and stable levels of light, food, nutrients, elements and water flow is the key to maximizing both coral growth and color in a reef aquarium. Just remember, nothing good happens fast!