A little info about the care of different types of corals. Each section will be broken into multiple parts so you can read about your favorite type of coral!
Soft coral – Soft coral have pretty minimal lighting requirements. Give them a little light, but often not too much, and they are happy. These types of corals do well on the sandbed or edge of the tank where lighting is often lower PAR (PAR stands for Photosynthetic Active Radiation. It’s the light that plants and corals can use to grow) like below 100 PAR. Some soft corals, like Zoanthids or Zoas for short, can handle higher values of light and thrive.
LPS – LPS, or Large Polyp Stony, corals come in a wide variety of light requirements. Most will do well with a middle level of light though. In terms of PAR think 100-200. Most need more than soft corals but less than SPS corals.
SPS – SPS, or Small Polyp Stony, corals generally need more light then the other types of corals. They should be placed higher up in the tank compared to other corals and towards the center of the light source. In terms of PAR think 200-400 levels here.
Placement – Where you place your corals will depend on a number of considerations. Where they are on the rockwork, how high up vs off to the side of the tank, or even how much water flow that spot gets. It is best to place your corals in a spot you think will work and watch them closely. If they don’t open up at all then something is wrong. They could be in too high of flow or they could be receiving too much light. If the corals stretch a large amount that means they need more lighting. After placing, wait a day or two and see how the coral looks. If it’s happy it should open up fully within a day of being placed.
Types of Lighting
There are a myriad of products on the market today. The types of lights can be split into three main categories: Metal Halide, T5, and LED lighting.
Metal Halide – Old fashioned perhaps but a tried a true source of light. Metal halides have been on the market almost as long as people have been trying to keep reef tanks in their home. It’s a very simple process to use one as they contain a few simple parts. The ballast is the part that plugs into the wall and controls the lights. A ballast is typically rated for a certain wattage of bulb and should be paired correctly. A reflector often plugs into the ballast. They come in all different shapes and sizes but the most important part is that they reflect light down and out across the tank. Without a reflector the majority of light made from the bulb would spill out, going everywhere but the water. The last part is the bulb. This part connects to the reflector. There are two types of bulbs out, single ended and double ended. Just like the name implies, the difference is how many ends will connect to the reflector. Double ended bulbs are a newer product and produce a better light spread but are a little harder to install than the single end bulbs, which just screw into the base like a regular light bulb.
Pro – A tried and true system proven to grow all types of corals including SPS. Years of knowledge and advice online. Plug and play system.
Con– May produce some heat in tank water if not vented well. Wattage of units are higher than LED. Single point of light may cause shadows in edges. Not many choices in bulb colors. Bulbs need changed once a year. Natural looking shimmer effect.
T5 – Another proven method is the T5 lights. Come in long tubes of various lengths, T5 by far gives the best light spread and prevents shadows from forming. There are quite a few choices of bulb colors to let you create that perfect look to your tank. I think these pair up well with both metal halide and LED lights as supplemental coverage.
Pro – proven to grow all corals including SPS. Less watts than the metal halide system. Does not heat up the tank water. Great light diffusion meaning no shadows in tank. Lots of bulb color choices.
Con – Large fixtures tend to be heavy. Light can look very flat in the tank.
LED – More recent advances in science and technology has allowed the use of LED lights to hit the market at decent prices. They do tend to cost a little bit more than the other types of lights and that can add up; especially if lighting up a large tank. They can offer a ton of control options allowing a user to pick out exactly what colors they want and how high they want to operate the lights. Higher end LED lights can grow SPS corals but they tend to have a strong shadow effect. Lower end LEDs can produce a discoball effect which most people are not a fan of. Some brands, like Kessil, can produce a shimmer effect in the tank that can rival a metal halide system.
Pro – little to no heat produced. Energy savings by using less watts. Lots of options to customize your own look. Some may have a desired shimmer effect similar to metal halides.
Con – Typically not considered plug and play and require some customization of the lights. There can be too many options and make it overly complicated. Easy to burn corals with these lights causing a need to ramp the lights up slowly over time.
Water quality is really important for all types of corals. Some people say that soft corals benefit from a “dirtier” tank; one that isn’t cleaned as often or has higher nutrients. That may be true but they will still do well in a clean tank. It’s important to note that while you want to keep nitrate and phosphate low, you do still need a little of those nutrients for all corals. A good goal is to get nitrates stable at or below 10ppm (parts per million – most test kits use ppm).
LPS and SPS corals generally benefit from having a really clean tank with low nutrient levels. Part of this is because a tank with lower nutrients is likely to have clearer water and let more light pass through to the corals.
Flow is a necessary thing in our tanks. It keeps the water circulated and keeps water chemistry equal in the whole tank. This is especially important for corals like SPS and LPS that need constant calcium and alkalinity to grow. Just like with lighting SPS like high flows, LPS moderate flows and soft corals lower flows.