How to Care for SPS Corals by Robert Farnsworth
Within the reef aquarium hobby, you often hear the terms soft corals, LPS and SPS used to identify different groups of corals. Grouping corals in this fashion is useful because it not only describes the coral itself, but also helps aquarium hobbyists understand what a particular coral will need from us (lighting, placement, flow, parameters, etc.) in order to survive.
If you missed our first article in this series, be sure to check out How to Care for LPS Corals when you're done with this article. It is written in the same easy-to-understand, no nonsense style.
Before we dive into SPS coral care, let's take a quick look at each coral type to identify their key features, similarities and differences:
Soft corals lack a rigid stony skeleton. Typically they require lower light and moderate to low water flow. They are often more forgiving with water quality and easier to care for. Common soft corals include Leathers, Zoanthids, Palythoa, Discosoma and Ricordia.
LPS: Large Polyp Stony Corals
Large Polyp Stony Corals consist of a rigid skeleton with large fleshy polyps. LPS usually require moderate to high light levels and moderate flow rates. They are a bit more forgiving with water quality compared to SPS corals. Growth rates and patterns vary dramatically from one species to another. Common LPS corals in the aquarium trade include Acanthastrea, Euphyllia, Favia, Fungia, Blastomussa, Dendrophyllia, and Tubastrea.
SPS: Small Polyp Stony Corals
Small Polyp Stony Corals have a rigid skeleton with small polyps and thin flesh surrounding the skeleton. They generally have high light requirements and prefer high water flow. SPS are very sensitive to water quality and are the most difficult corals to grow in an aquarium. Common SPS corals include Acropora, Montipora, Pocillopora, Stylophora, and Seriatopora.
Generally speaking, SPS are demanding and require more attention when compared to LPS and/or soft corals. The reason is SPS corals are more sensitive to light and water quality. SPS can lose tissue and die within hours for even a small lapse in attention.
Let's now discuss what to look for in a healthy SPS coral at your local fish store.
You will want to first look at the tissue of the coral. This is the thin membrane that surrounds the calcareous skeleton. You want to make sure the skeleton is not exposed and pay careful attention to the color of this tissue. SPS corals can quickly turn brown if not given the proper environment to thrive. SPS corals that have turned brown are still alive; unfortunately, it takes time for them to regain the brilliant colors healthy SPS are known for. Watch for very light or "bleached" tissue, too. This is a bad sign and resulting from too much light, improper flowand/or insufficient nutrients.
Next, look at the polyps. You want to see healthy polyp extension. Research the corals you are considering before you shop so you know what to look for. SPS polyps can vary dramatically, so it's important to do a little research on what the polyps should look like once extended. Google Images or searching your favorite message board should do the trick.
Millepora, for example, are known for their long polyps. A healthy coral will look bushy like the specimen below:
Montipora has different shaped polyps that do not extend very far:
Once you've brought the coral home safely, be sure to give it plenty of time to acclimate to your aquarium's water temperature and chemistry. You may also want to dip the coral as a preventative measure to avoid introducing unwanted hitchhikers into your aquarium system.
SPS corals, in general, are going to require higher levels of light and flow compared to most LPS and soft corals. This is because they are usually found in the top areas of the reef zone close to the surface. Naturally, these areas of the reef are more turbulent and receive more intense sunlight. Therefore, be sure to provide plenty of flow and lighting for your new SPS coral. If the coral does not appear to thrive where you place it initially, it is perfectly fine to try another spot in your tank. Be sure the coral is not positioned too close to other corals that may sting it.
Now, the tricky part: ensuring water quality is consistent. Changing water parameters can kill SPS corals very quickly, sometimes within a matter of minutes. Maintaining calcium and alkalinity are the most important factors for success as this ensures the corals have the building blocks needed to grow their skeleton. Maintaining calcium and alkalinity will help keep your pH stable as well, so you'll experience less swing on a daily basis which reduces stress on all of your tank inhabitants. Dedicated SPS gurus usually invest in a calcium reactor since a fully stocked SPS aquarium will have a high demand for calcium and alkalinity supplementation.
It is also important to keep nitrates at a minimum and phosphates at undetectable levels because these parameters can impede the growth of corals and lead to a slow decline. Reference our Reef Tank Parameters chart or check out the links at the bottom of this article for more information.
Though a majority of the energy a coral will use to grow is from photosynthesis, you can supplement with foods. Since SPS have small polyps, you want to use small particle size foods. Phytoplankton and Zooplankton are the most popular foods, but you will also see many prepared coral foods such as Reef-Roids and Coral Frenzy. Once food is added to the aquarium, you may notice that SPS corals extend feeder tentacles that look like small white strings. These are used to gather food from the water column and are a perfectly normal and healthy sign from the coral.
Although intimidating, SPS corals are often found in the most awe-inspiring reef aquariums because of their amazing arrays of color and intricate aquascaping abilities. They do require patience and dedication, but ultimately the rewards are bountiful. In my personal experience, the most satisfaction in the hobby has come from growing small fuzzy sticks into large coral colonies I can share with friends.