Article by Peter Cunningham
A topic that is not discussed very often is aquarium lighting for reef tanks. Although this topic is not discussed very much it is very important within a salt water reef tank.
After water quality the next most important thing is aquarium lighting for reef tanks, followed closely by water movement.
Water quality gives the tank stability as well as providing the corals with the essential elements. Aquarium lighting provides the corals with energy which they then use to grow. Water movement allows nutrients to be delivered to the corals for them to feed upon, as well as washing away waste. Water movement is also essential when natural filtration is used in the reef tank.
Inside all corals are millions upon millions of what is called symbiotic algae. The only exceptions are those corals which are classified as non-photosynthetic. These obtain their energy from feeding rather than from light itself. Photosynthetic corals obtain their primary source of energy from light and then also actively feed to obtain more energy. The symbiotic algae within the corals obtain energy from the light and then pass this energy on to the coral itself – a match made in heaven!
Different corals have different lighting requirements. For example, short polyp stony corals require much more intense lighting than soft corals do.
When choosing aquarium lighting for reef tanks you need to check two things in your reef tank. The first is the corals themselves, so that you can ascertain their requirements, and the other is the depth of the aquarium itself. Checking the depth is important as light can only penetrate so far into water before the colour is removed. It is amazing how quickly water can remove colour from light.
The depth of your aquarium as well as the corals you keep will determine which type of lighting you require. For example, if you keep soft corals then you could possibly just use fluorescent tubes. However, if you keep short polyp stony corals then metal halide lighting will be required. The depth needs to be checked because if you have a deep aquarium then the colour might not penetrate to the bottom of the aquarium. Water has the ability to be able to strip out colour at an amazing rate, therefore if you have a deep aquarium you will need lighting of enough power to be able to push the light to the bottom of the aquarium.
Another component of aquarium lighting for reef tanks which needs to be considered is that of Kelvin. Kelvin is the colour output and the higher the rating in the Kelvin scale the bluer the light will be. At the other end of the scale the lower the rating the more yellow/red it will be. Normally in a reef aquarium a Kelvin rating of 10,000K to 13,000K is utilised. This is a white/blue colour which replicates life on the reef at a depth of about 30m.
When placing corals into your reef aquarium you will need to first check what their lighting requirements are and then place them at the bottom of the reef tank and slowly move them up over time until they are in their final position.
Peter Cunningham and John Cunningham combined have been keeping salt water aquarium’s for nearly 35 years. Their website Salt Water Aquarium provides a wealth of resources for learning how to start and maintain salt water aquariums.