Marine Aquarium Lighting
A marine aquarium can vary with it's lighting needs. Because a "Fish Only" or a "Fish Only Live Rock" setup does not have specific lighting needs they will not be covered in this article. This article will cover three basic marine tank groups, and their lighting needs. Keep in mind that these recommendations will be broad and some corals and inverts will have more specialized needs that will not be covered. But for all intents and purposes 95% of all common coral and anemone will be covered here.
Thrive VS Survive
Ever wonder why some tanks are colorful and vibrant and some are not? Light is one piece of a segmented puzzle that makes great color happen. Flow, water quality, and many other factors also contribute. In the tissues of many corals (minus your sun corals and a few carnivorous others) are algae that these corals feed off of and coexist with. This symbiotic algae is called Zooxanthellae. Generally more light means healthier Zooxanthellae and more of a food source for your coral. The intensity of the light will vary with each type of coral and some even prefer indirect light over direct. The three major categories of coral (plus photosynthetic anemones) and their basic light needs (PAR) are...
- Soft Coral... Low. 100 to 200 PAR
- LPS... Low to moderate. 100 to 300 PAR
- SPS... Moderate to very high. 300 to 1000 PAR
- Anenomes... High. 400 to 600 PAR
PAR vs Watts
PAR is a measure of photosynthetic light. Watts are a measure of energy usage. It is a major fallacy in the aquarium hobby to tell people they need X number of Watts per X of gallons or liters of liquid. But it is still commonplace for some pet stores and LFS to do so. Lamps, ballasts, and light types will all vary in the amount of PAR they will put out for a given watt.
Fluorescents come in many varieties and range in quality. The most popular are PCs, VHO, and T5 varieties.
- PCs or power compacts are inexpensive, but they are not ideal most of the time either. Much of the light derived from a PC is lost into the adjacent lamp, and no good reflectors exist for them.
- VHOs are old tech and are relatively cost effective as well. They can be run with internal reflectors or external. External being more efficient. Their main draw-back is that due to their diameter it is difficult to get enough of them over a tank to get high enough par levels.
- T5s are a smaller in diameter version to the VHO. Their smaller size makes them easer to design efficient reflectors for them, and their small size allows more lamps to be run over an aquarium. Keeping the end-caps cooled with a fan will also increase their output as well. Also the most expensive of the florescent types.
Metal halide lighting is quite popular in the hobby, and for good reason. It is cost effective, dense, intense and somewhat efficient. Metal halides do, however, require a well designed reflector to get all that light to its destination. Popular reflectors are the Lumen Max series, and Lumenarc series. With data from well known photon expert Sanjay Joshi backing up their quality with data. Common lamp, ballast, and socket sizes for metal halides are 150, 250, and 400 watts. It is recommended to run one reflector, and lamp per 2 linear feet(60 cm) of tank. Lamp wattage will depend on tank depth and livestock, but for most mixed reef tanks consisting of a mixture of all coral types a 250 watt setup will suffice. An all SPS tank may, however, wish to opt for either a mixture of 250 watt halides and T5 florescent lamps or out-right 400 watt halides per 2 feet square.
I am partial to these, two of my three tanks use them because of they are fairly maintenance free for about 4 to 5 years at a time. There is one caveat and that is in order to get the intensity of a halide or T5 from these light sources many of them must be run. Wiring becomes very complex and cost is quite high, though it is much lower than when I setup my first. Expect to spend orders of magnitude higher for an LED setup over a T5 or metal halide setup. Over time these do pay for them selves but only after 3 years of use. Emitters do vary and at this time the only ones worth looking at are Cree, Luxon, and Seoul Semiconductor. With the Cree emitters being by far the most efficient. Optics for LEDs operate much in the same way that reflectors do for other light sources and adding them to your setup will increase the intensity of the light that reaches your corals.
This is a new and emerging light source. This light source works by exposing gasses in an enclosed quartz tube to high frequency microwaves. The gasses excite and then emit light. Due to the fact that plasma lighting has no electrodes lamp life is very long, as in 100,000+ lamp hours before noticeable decrease in intensity. This light source is also very efficient meaning less heat waste is generated to create the light. Currently this is a very cutting edge technology and is very expensive to purchase. Watch for it on the horizon.