The world is home to around 6,000 coral species, many of which thrive in high flow, or what is oceanic current in the natural wilderness. However, the enormous diversity of corals also means that you can’t choose a specific high flow rate in your reef tank for each of those you choose.
Here are the top 10 corals that like high flow in your reef tank:
- Green star polyps
- Millepora alcicornis
- Acropora millepora
- Acropora lokani
Aquarists have distinct takes on high flow rates. I may think 2,000 gallons/hour (7,500 L/hr) is high flow for my 40-gallon (150 L) tank, but you might have a different yardstick. I have factored in the standard range of high rates and the reality that the flow varies within a reef tank.
1. Green Star Polyps
Green Star Polyp (GSP) is among the more adaptable corals you can have in your reef tank. The soft coral isn’t too demanding, be it flow, light, parameters, or the surface to grow on. Its ease of care has made Green Star Polyps a popular coral for beginners.
You don’t have to worry about the flow rate as Green Star Polyp can survive in low to moderate currents and thrive in reasonably high flows. Furthermore, you may place GSPs at various levels inside your reef tank and on any surface, be it rock, glass, plastic, or even other corals.
Green Star Polyp grows faster than many corals. Because of this, you can place them in relatively vacant parts of your reef tank, and they’ll soon occupy the available space. However, GSPs have the ability to grow over other corals, so you may have to watch out for such invasions.
While GSPs can be slightly invasive, they don’t have stinging tentacles. Thus, there’s no severe threat to the other corals nearby. Also, Green Star Polyp grows well in regular saltwater parameters, but you must avoid abrupt & significant changes, whether in minerals or alkalinity.
Xenia is another soft coral that can endure good water flow. In the oceans, Xenia elongata thrives in strong tidal conditions. However, you must place them in areas within the reef tank that have high indirect flow, not close to the powerheads.
Xenia has a natural tendency to pulsate. This pulsing phenomenon makes it appear alive and enhances the aesthetics of a reef tank. The Green Star Polyps’ short tentacles sway in water, too. And, both these soft corals grow quickly, so your reef tank will have glorious activity.
If a Xenia coral stops pulsing completely, the high water flow is probably too strong for it. Or, it hasn’t acclimatized to the reef aquarium environment. Change its placement. Xenia grows well at shallow depths when exposed to intense light. You must ensure both so it can thrive.
Like the Green Star Polyp coral, Xenia has an overgrowing problem. This fast growth makes both corals ideal for beginners as available spaces in the reef tank can be filled up quickly. On the flip side, you must be proactive to prevent these soft corals from invading others.
While shopping, you can use any of its alternative common names, such as pulse coral, hand coral, pulsing xenia, red sea xenia, or pom-pom coral.
Moving beyond soft corals, Montipora is a safe choice if you go for a high flow rate of perhaps 50x or 60x your reef tank volume per hour. A small polyp stony coral (SPS), Montipora isn’t a species but a genus. There are 85 identified species, like leaf plate montipora, aka vase coral.
Most small polyp stony corals thrive at high flow rates. Some SPS corals can grow well even when a high flow is directly aimed at them. Unlike some of the other SPS corals in the Acroporidae family, Montipora species are relatively easier to grow and maintain.
You don’t need spectacularly bright or intense lighting for Montipora corals. Many hard corals demand metal halides for strong lighting, but you can use compact fluorescent lights for Montipora. Also, the temperature requirements are a standard 75 °F to 85 °F (24 °C to 29 °C).
Amateur aquarists often steer clear of small polyp stony corals due to the demanding parameters and infrastructure, including lights, temperature control, and feeds. Montipora isn’t a daunting coral. However, it doesn’t fare well in reef tanks with poor flow rates and low light.
4. Millepora Alcicornis
Millepora alcicornis, also known as sea ginger, is a stony hydrocoral that grows well in high flow. This species isn’t the same as Acropora millepora. Millepora and Acropora are two different genera in the Milleporidae and Acroporidae families, respectively.
Millepora is often referred to as fire coral. Scientifically, a fire coral is a hydroid. However, sea ginger or Millepora alcicornis has a calcareous skeleton. Unlike Acropora species, sea ginger is relatively easier to grow and manage. Also, Millepora alcicornis can form expansive colonies.
Sea ginger grows by branching and encrustation. Thus, you’ll have a coral in your reef tank that grows horizontally and vertically. Also, the coral will encrust its surrounding objects and provide a somewhat exotic appearance.
5. Acropora Millepora
Acropora millepora is a sturdy coral that loves high flow rates. You wouldn’t have to worry about strong flows, but you have to provide the necessary lighting for the coral to grow naturally. Many beginners and also intermediate aquarists are somewhat disappointed with the coral in a tank.
One challenge is the quality of lighting. You may attain the intensity or brightness. However, you cannot facilitate the naturally glorious and colorful growth of Acropora millepora with ordinary LED or other lights. Ideally, you should have a UV light setup.
Acropora millepora has several natural colors, from pink and purple to green, orange, and blue. Even in blue light setups, this coral may not be able to replicate its natural hues inside a reef tank. Yet, the intricate features of this coral and its unique shades will make you wonder.
Acropora small polyp stony corals grow in clusters. They’re somewhat challenging to maintain. If you can ensure the requisite parameters, one of which is a high flow, the eventual outcome will be a matter of pride and utmost satisfaction.
6. Acropora Lokani
Acropora lokani is another hard coral that endures high flow effortlessly. The entire Acropora genus and its species are suitable if you want to sustain a high flow rate in your reef tank. Hence, the choice of particular species depends on the parameters you can maintain.
The Acropora lokani species is much less demanding than many in its brethren. Slight temperature changes or lighting variations will not impair the growth nor threaten the survival of this coral. The coral is more adaptable than most, but you must acclimatize it slowly.
The thick, stout branches or fingers of Acropora lokani form a bush-like appearance, in contrast to other table-type clusters and encrustations commonly seen in small polyp stony corals. Consequently, the distinct structures of this coral will add significant diversity to your reef tank.
The other noteworthy feature of Acropora lokani is its range of colors. The natural hues are brown, blue, and cream. However, you’ll also find shades of purple, pink, and others depending on the exact growing conditions or the sustained environment in a reef tank.
Zoanthids, fondly known as zoas, are often referred to as soft corals. Technically, they aren’t corals but a type of Hexacorollia. Interestingly, the Hexacorallia subclass includes all stony corals. Zoas are made of polyps, and they can form expansive colonies in a short span.
Zoas can survive high flows. They’re among the hardiest soft corals you can have in your reef tank. A reef tank with a substantially strong flow rate will still have areas with moderate-high currents. The zoas can fit in there conveniently.
Furthermore, zoas tend to allow detritus buildup that low to moderate water flow will not remove, thus preventing the regular growth and expansion of the colonies. High flow can flush out the detritus and enable the zoas to develop amazing colors and illustrious growth.
Also, zoas aren’t demanding at all. They are ideal for beginners with limited reef tank equipment and accessories. Besides, if you choose one or two demanding Acropora species, you’ll want a few corals that don’t need much attention or tedious maintenance.
Zoas grow well in low light. They don’t like highly intense or bright lights unless acclimatized. This attribute is helpful, too. You’ll have to place hard and stony corals at shallower depths so they can get sufficient light to thrive. Zoas can be placed farther down, and they’ll be fine.
Back to stony corals, Cyphastrea is a quaint type of coral. Their growth isn’t like small or large polyp stony (LPS) corals, somewhere midway. The unique form & structure of Cyphastrea has led to the common name ‘brain coral.’ Several species in its family are brain corals.
Like other SPS and LPS corals, Cyphastrea can comfortably endure high flow. In fact, these corals require strong flows. Cyphastrea and other brain corals don’t have long tentacles like many LPS corals and are unable to form colonies swiftly like fast-growing soft corals.
Hence, high flow or strong currents ensure these corals get the nutrients to grow naturally. Also, high flow prevents detritus buildup and facilitates the parameters, including the environment, to remain uniform or consistent throughout the reef tank.
Many aquarists prefer high flow because of its effect on the parameters and localized environments within the reef tank. Everything from alkalinity to the presence or distribution of phosphates, nitrates, magnesium, and calcium inside the reef tank depends on the flow.
Hard or stony corals are a natural choice for reef tanks with high flow rates. However, some SPS and LPS corals don’t thrive when subjected to a strong direct flow. You need at least a few corals that are sturdy enough to be placed closer to the powerheads.
Pocillopora, also known as cauliflower coral, can endure strong direct flows. Most Pocillopora species, like meandrina, grow at shallow depths and face mighty waves. These robust corals will be comfortable in your reef tank and can fill up those places closer to the powerheads.
Pocillopora corals may be cream, green, pink, and other shades depending on their growing conditions and the reef tank environment. They develop a bushy appearance as the branches grow and flatten, thus providing some visible heft to your reef tank aesthetics.
In the wild, Pocillopora corals are known to provide refuge to small fishes, crabs, and shrimps. They may do the same in your tank. Also, Pocillopora’s rounded overall form with short & lumpy branches complements both large stony polyps and soft corals that have contrasting features.
You may consider Pocillopora damicornis and meandrina (cauliflower or lace corals), elegans, and verrucosa, among other species in the genus.
Last but not least, Chalice corals can add some more splendorous versatility to your reef tank while easily enduring high flow rates. Chalice corals are stony that require stable reef tank environments. Don’t add them if the nutrients, lights, and water flows are not properly regulated.
Chalice corals are so named because of their natural form, which resembles a cup, bowl, or goblet. This shape facilitates detritus buildup. Thus, a high flow rate is necessary if you want Chalice to grow and subsequently thrive.
Most Chalice species are fascinatingly colorful. Many of them are very pretty. These species belong to various genera, including Pectinia, Echinopora, Mycedium, and Physophyllia. Irrespective of that, the showstoppers can be aggressive, especially towards fellow Chalices.
The varieties in the genus generally don’t have long extendable tentacles, but some do, so place them accordingly. Also, Chalice corals can cause damage if their bodies are in contact. Therefore, be sure to watch out for not only the tentacles but also if the bodies are in alarming proximity.
These stunning additions to a reef tank have a few challenges, too. The corals prefer to eat at night and gorge on magnesium. You need to figure out the right feeding routine and food types for Chalice corals. However, they’re also capable of self-nourishment through photosynthesis.