SPS Coral Types – An Intro To SPS Reefkeeping

Last Updated: May 18, 2026

SPS corals are not hard to keep because of what they need. They’re hard because they don’t forgive inconsistency. I’ve watched reefers with decades of experience lose acropora colonies overnight from a single alkalinity spike. And I’ve watched beginners succeed with SPS when they built the right system and kept their hands out of it. The coral itself isn’t the obstacle. Your water column is.

Stable mediocre parameters beat perfect parameters that swing. Every time.

Small polyp stony (SPS) corals are the pinnacle of reef aquarium keeping. In the wild, corals like staghorn and table acropora build the backbone of tropical reef systems, housing thousands of species and defining the reef’s vertical structure. In the aquarium, they deliver that same visual impact at the top of the rockwork. No soft coral or LPS can replicate what a full SPS colony looks like under 400 PAR. But that beauty comes with demands that most hobbyists underestimate.

After 25 years in this hobby and time running fish stores where we sold frags and watched customers succeed and fail, here’s what I know: SPS is not the next step after soft corals. It’s a different discipline entirely.

What Is SPS Coral?

SPS stands for small polyp stony coral. These are reef-building corals in the order Scleractinia that construct calcium carbonate skeletons as they grow. Their polyps are tiny compared to LPS corals, which is where the name comes from. The skeleton is exposed and rigid, covered in a thin layer of tissue called the coenosarc that connects all the individual polyps.

Zooxanthellae, the symbiotic algae living inside coral tissue, fuel SPS growth through photosynthesis. This is why light quality and intensity matter so much: cut the PAR, cut the energy supply. Without adequate light, zooxanthellae compensate by producing darker pigments (the dreaded “brown out”) or the coral simply starves.

Taxonomically, SPS corals belong to the Scleractinia order and the Hexacorallia subclass, which means their polyp symmetry is divisible by six. In the wild, they colonize the upper reef zones where wave energy is highest and sunlight is most direct. That’s your setup blueprint right there: high light, high flow, near-constant stability.

SPS vs. LPS vs. Soft Corals

Understanding where SPS sits in the coral hierarchy is critical before you buy your first frag.

Soft corals have no true calcium carbonate skeleton. They’re held up by water pressure and small internal spicules. They’re the most forgiving: many tolerate poor lighting, inconsistent flow, and imperfect water chemistry. Great starting point for new reefers.

LPS corals have a true skeleton but large, fleshy polyps that extend outward dramatically. Most LPS live lower on the reef where flow is gentler and light is indirect. They need more stable parameters than soft corals but are still more forgiving than SPS.

SPS corals are the reef builders. Their skeleton grows continuously as long as chemistry supports it. They live at the top of the reef, need the most light, and react to water chemistry changes faster than any other coral group. A 2 dKH alkalinity swing that a leather coral shrugs off can bleach a milli acropora colony in 48 hours.

Who Should Actually Keep SPS

This is where I’m going to be direct: SPS is not for everyone, and there’s no shame in that.

You’re ready for SPS if your tank has been running stable for at least 12 months, you test alkalinity at least twice a week, you have a dosing pump or calcium reactor, your lighting can hit 200+ PAR at the rockwork, and you’ve already kept LPS successfully without unexplained deaths. If any of those aren’t true, start with Montipora and use it as your chemistry test subject.

You’re not ready if you’re still troubleshooting brown algae, your parameters swing week to week, or you’re on a hang-on-back filter with stock lighting. That’s not a judgment. That’s just chemistry.

Water Parameters

These are the target ranges I recommend based on what I’ve seen work consistently. Note that stability within range matters more than hitting exact numbers.

Parameter	Target Range	Notes
Alkalinity	8.0–9.0 dKH	Most critical; swing tolerance <0.5 dKH/day
Calcium	420–450 ppm	Linked to Alk; balance them together
Magnesium	1,300–1,350 ppm	Stabilizes Alk and Ca relationship
Nitrate (NO3)	1–5 ppm	Zero nutrients = poor color and brown out
Phosphate (PO4)	0.03–0.07 ppm	ULNS tanks brown out; some PO4 is good
Salinity	1.025 / 35 ppt	Auto top-off is non-negotiable
Temperature	76–78°F (24–26°C)	Upper end accelerates growth but reduces tolerance
pH	8.1–8.3	Tie CO2 injection to your apex controller
Lighting (PAR)	200–400+ PAR	Species-dependent; acropora needs more

Lighting and Flow

High-quality lighting is not optional for SPS. A programmable LED fixture with full spectrum control is the minimum. The EcoTech Radion G5 is the standard for serious SPS tanks for good reason: consistent spectrum, reliable PAR output, and full programmatic control over ramp-up and ramp-down so corals aren’t shocked by sudden light changes.

Water flow is equally critical. Random, turbulent flow keeps waste from settling on coral tissue, delivers nutrients to polyps, and prevents dead zones inside dense colonies. Most SPS tanks run two or more powerheads in alternating patterns. A single powerhead pointed at the rock creates a dead zone on the back side of every colony it hits.

Filtration: a sump system is standard in any SPS setup. More water volume means more stability, more room for biological filtration, and easier nutrient export. Running SPS without a sump is possible but significantly harder to maintain stable chemistry.

Types of SPS Coral

SPS corals span dozens of genera, but the hobby trades around a handful of key groups. Here’s what you’ll actually encounter.

Montipora

• Scientific Name: Montipora spp.
• Difficulty Level: Easy-Moderate
• Temperament: Non-aggressive
• PAR Requirements: 150+ PAR
• Flow Requirements: Moderate-High
• Placement: Middle to Upper
• Origin: Indo-Pacific

Montipora is the entry point for SPS. This genus covers encrusting, plating, and branching growth forms and comes in virtually every color. The plating “Monti Cap” varieties grow in large circular disks with white growth tips at the edges. Montipora digitata branches with thicker growth and produces antler-like structures over time.

Why start here? Montipora tells you if your system is SPS-capable before you invest in a $200 acropora frag. It needs SPS conditions but tolerates slightly more variation than the more demanding genera. Think of it as a living test kit. If your Monti is browning out, your nutrients are off. If the tips aren’t showing white growth, your alkalinity is low or your PAR isn’t adequate.

Read our full Montipora coral care guide for detailed setup and color optimization tips.

Pocilloporidae Family: Pocillopora, Stylophora, Seriatopora

• Scientific Name: Pocillopora spp., Seriatopora spp., Stylophora spp.
• Difficulty Level: Easy-Moderate
• Temperament: Non-aggressive
• PAR Requirements: 200+ PAR
• Flow Requirements: High
• Placement: Middle to Upper
• Origin: Indo-Pacific

The Pocilloporidae family gives you the classic “bird’s nest” look. These three genera are closely related and often confused with each other on frag discs.

Pocillopora has thick, stubby branches with a slightly fuzzy polyp extension. Most common colors are green, purple, and pink. These handle higher flow well due to their robust branch structure.

Stylophora is nearly identical to Pocillopora at the frag stage. At colony size, Stylophora grows in a more uniform, ordered pattern while Pocillopora tends to sprawl. Both are good beginner-SPS choices.

Seriatopora (the true bird’s nest) has very thin, pointed branches that create a delicate twig-like structure. Polyps sit farther apart on the branches. These are more delicate to handle and transport but frag easily. Colors range from green to purple to bi-color combinations.

Acropora

• Scientific Name: Acropora spp.
• Difficulty Level: Hard
• Temperament: Non-aggressive
• PAR Requirements: 250–400+ PAR
• Flow Requirements: High
• Placement: Upper third of tank
• Origin: Indo-Pacific (some species in Caribbean)

Acropora is the pinnacle. Full stop. A mature, multi-colony acropora display is one of the most impressive things in the aquarium hobby. There are hundreds of species, from tight table corals to elegant stag horns to intricate milli frags, and the designer trade around named morphs is its own subculture in reefing.

What makes acropora genuinely difficult: they sense chemistry changes faster than any coral I’ve worked with. They’re the canary in the coal mine. Every pump failure, every top-off malfunction, every bad water change gets reported instantly through RTN (rapid tissue necrosis) or STN (slow tissue necrosis). You don’t get the week of warning you’d get from a hammer coral. You wake up and the frag is bare skeleton.

Read our full Acropora coral care guide for species selection and advanced parameter management.

Difficulty Tiers: Beginner to Advanced SPS

What People Get Wrong About SPS

They chase zero nutrients. The “ultra-low nutrient system” (ULNS) approach has produced countless brown, stressed acropora tanks. SPS needs zooxanthellae to produce the pigments that give it color. Zero nitrate and phosphate starves those pigments. You want 1–5 ppm nitrate and 0.03–0.07 ppm phosphate for full color expression. A completely barren nutrient profile produces a beautiful beige coral.

They think stability means weekly testing. If you’re testing alkalinity once a week on an SPS tank, you have a 7-day blind spot. Alk can swing 1–2 dKH between your tests and you’d never know until the coral starts to bleach. Twice-weekly minimum for alkalinity, calcium, and magnesium is the standard in serious SPS systems. Daily testing is common in heavy acropora tanks.

They add SPS to an immature system. Twelve months is the standard guideline because that’s roughly how long a reef system takes to establish stable bacterial populations, work through the typical algae succession phases, and reach predictable parameter behavior. An 8-month-old tank can feel stable, but the chemistry swings are often just slow enough that you don’t catch them until the coral reacts.

They confuse “hardy SPS” with “easy.” Montipora is the hardiest SPS. That doesn’t mean you can keep it on a power compact light with no dosing. It means it tolerates slightly more variation than Acropora. All SPS requires SPS conditions. Full stop.

Should You Keep SPS Coral?

Good fit if: You’ve kept a successful LPS reef for over a year, your parameter testing is already routine, you have a sump, quality lighting at 200+ PAR, and you’re willing to start with Montipora before moving to acropora. SPS is genuinely one of the most rewarding things in the aquarium hobby. A full acropora display tank is a sight that doesn’t get old. Just build toward it correctly.

Compared to LPS: If you want color and movement with more forgiveness, LPS is the better choice. Hammers, torches, and brain corals are visually stunning, reward good husbandry, and don’t punish minor parameter lapses. Choose SPS when you’re ready to go to the next level of chemistry management and want the reef structure that only branching stony corals can provide.

FAQ

What is the easiest SPS coral to keep?

Montipora capricornis (plating Montipora) and Pocillopora are the most forgiving SPS genera. They still require SPS-level lighting, flow, and stable parameters, but they tolerate minor variation better than Acropora. Frags are inexpensive and widely available, making them the standard starting point.

When can you add SPS corals to a new reef tank?

The standard recommendation is 12 months minimum. This allows enough time for the nitrogen cycle to fully establish, algae succession phases to complete, and parameter behavior to stabilize. Some experienced reefers add Montipora to well-established systems at 6–8 months, but the failure rate is significantly higher before the one-year mark.

Why are my SPS corals turning brown?

Browning out is usually caused by one of three things: too little light (increase PAR or adjust photoperiod), too much phosphate (check exports and feeding), or too little nitrate (paradoxically, zero nutrients causes the zooxanthellae that produce color pigments to compensate with darker pigments). Target 1–5 ppm nitrate and 0.03–0.07 ppm phosphate for best coloration.

Can SPS corals sting each other?

SPS corals are not aggressive in the way LPS corals are. They don’t deploy sweeper tentacles to attack neighbors. But as colonies grow and branches contact each other, tissue necrosis can develop at contact points. The bigger danger is LPS nearby: hammer and frogspawn sweeper tentacles can reach SPS and cause rapid tissue loss. Keep LPS and SPS in separate zones of the tank.

How do I frag SPS corals?

SPS frags well because the calcium carbonate skeleton cuts cleanly. Use a band saw (Gryphon C-40 is the standard), bone cutters, or a Dremel with a diamond blade for smaller pieces. Cut branches 1–2 inches (2.5–5 cm) from the colony, mount immediately on a plug or rubble with super glue gel, and dip in coral dip before placing in the tank. New frags are vulnerable to parameter swings for 2–4 weeks while they recover from the cut.

Closing Thoughts

SPS reefkeeping is one of the most technical disciplines in the aquarium hobby and one of the most rewarding. The chemistry management alone is a skill that takes time to develop. But when you get there, a mature SPS tank is something that very few hobbyists achieve and even fewer forget.

Start with Montipora. Get your dosing dialed in. Run a stable system for six months before you touch acropora. That’s not a restriction. That’s the fastest path to keeping acropora long-term.

📘 Want to learn more? This article is part of our complete Saltwater Fish & Reef Guide. Your ultimate resource for marine fish, coral care, reef setup, and more.

References

• World Register of Marine Species: Scleractinia taxonomy
• Practical Fishkeeping: Husbandry and care advice
• Reef Builders: SPS coral keeping and advanced reef chemistry