Many reef-keepers are under the impression that if they get water quality parameters to match a certain formula, their corals will color up and thrive. These parameters have aquarists chasing “numbers” and often lead them to making changes and constant adjustments to the aquarium at the expense of environmental stability. It’s possible to be so focused on chasing those specific numbers to achieve color and growth that you miss the bigger picture: achieving a stable environment. So, stop chasing “numbers” and keep the following discussed pillars (in this four part series) of reef-keeping stable to see what color and growth your coral can produce.
You’ve seen beautiful, colorful reef tanks that have been running trouble-free for years. Ever wonder what the secret is? They’re not chasing numbers! They all were maintained by focusing on what we call the Four Pillars of Reef-keeping: Lighting, Water Flow, Nutrition and Filtration. Your focus should be on keeping these foundational factors stable… unchanging and stop focusing on chasing numbers. It’s a time-proven path to having great-looking corals and a beautiful reef tank. So, let’s jump into the First Pillar: Lighting.
Photosynthetic Active Radiation
With reef lighting it’s all about providing photosynthetic active radiation or PAR. PAR is the light wavelengths symbiotic algae in coral tissue need for photosynthesis. All high-quality reef lights provide light in the PAR spectrum.
PAR can be measured with a PAR meter. The unit of measure is “micromole photons per square meter per second” (molm²sec). In the hobby we refer to PAR levels as simple numbers like “150”. PAR measurements are made by placing a sensor under water. PAR is relative to distance from the light source. A LED fixture placed over a shallow aquarium will produce a higher PAR rating than the same light over a deeper tank. Most reef light manufacturers provide PAR levels based on distance from the light. PAR charts show PAR levels at different depths in the aquarium, so you can get an average level directly under the LED fixture.
Research shows that the ideal PAR level for corals is 100-200. This level has been proven to maximize photosynthesis rate of the zooxanthellae, which will also maximize coral growth. Boosting the PAR up to 200-400 will bring out a little more coloration but could also reduce growth rates when chasing color. It’s a trade-off many reefers accept. Going above this PAR range inhibits coral growth and may lead to bleaching. So, in this sense, “chasing numbers” of PAR is ideal as oppose to a certain set of water parameters as previously mentioned.
Use the light manufacturers PAR chart to determine which fixture is sized correctly for your aquarium. If you have your own PAR meter, use it to dial-in the proper PAR level by adjusting the light fixture’s intensity or the height the light is mounted. Once you’ve provided the correct PAR, set the photoperiod and sunrise and sunset dimming curve, if your light has that option. Remember, were going for stability. Once the lighting is set up, don’t make any unnecessary changes.
Internal Clock is Ticking
There is growing evidence that animals, plants and even corals have an internal clock that responds to light cycles. Known as circadian rhythm, this internal clock functions on a 24-hour cycle and regulates many biochemical functions within the cells. Disruption of the light cycle appears to cause stress to the organism. That’s why minimizing changes in your reef’s lighting is important to the long-term health of the corals and other aquatic life. Stability doesn’t mean you can’t make adjustments or switch out a fixture. You just need to be aware that your corals thrive and color up best when they receive the right PAR level and have a consistent lighting cycle.
The importance of PAR and a stable light cycle is a key one of the 4 pillars for having vibrant color coral and growth, contributing to their well being in captivity for many years. In Part 2 we’ll explore the second pillar of Stop Chasing Numbers! Chase Coral Color: Water Flow and its dramatic affect on the entire reef ecosystem, including your corals.