Acropora Care Guide: How to Keep SPS Corals Thriving
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Acropora Care Guide: How to Keep SPS Corals Thriving
Among reef keepers, Acropora corals hold legendary status. Their branching, tabling, and bushy growth forms create the architectural backbone of natural coral reefs. In the aquarium hobby, successfully keeping Acropora is considered a milestone achievement.
They can be demanding, but the reward of a thriving SPS (Small Polyp Stony) colony in full color is unmatched.
What Are Acropora?
Acropora is a genus of stony corals with more than 150 described species. They are among the most important reef-building corals on Earth, dominating many shallow reef environments throughout the Indo-Pacific and parts of the western Atlantic.
In reef aquariums, some commonly kept species include:
Acropora millepora
Compact branching growth with vibrant coloration. Often considered one of the more forgiving Acropora species.
Acropora tortuosa
Known for deep blue and teal coloration. Often forms irregular branching structures and is highly sought after.
Acropora valida
A fast-growing branching Acropora that adapts well to aquariums with stable parameters.
Acropora lokani
A slower-growing deepwater species known for intense purple and pink coloration.
Water Parameters: The Foundation of SPS Success
Acropora are extremely sensitive to water chemistry. Stability is far more important than chasing a perfect number.
Recommended ranges for healthy Acropora systems:
Temperature
76 to 79°F (24 to 26°C)
Salinity
1.025 to 1.026 specific gravity
pH
8.1 to 8.3
Alkalinity:
8 to 9.5 dKH
Calcium:
400 to 450 ppm
Magnesium:
1300 to 1400 ppm
Nitrate:
2 to 10 ppm
Phosphate:
0.02 to 0.08 ppm
The golden rule of SPS keeping is simple.
Stability beats perfection.
A tank that stays consistently at 8 dKH every day will outperform one that swings between 7 and 11 dKH, even if the higher number appears acceptable.
Calcium and Alkalinity Supplementation
As Acropora grow, they rapidly consume calcium and alkalinity. Maintaining these elements requires active dosing.
Two-Part Dosing
Examples include BRS 2-Part or similar systems.
- Easy to use
- Highly controllable
- Ideal for most hobbyists
- Works well with dosing pumps
Calcium Reactor
- Excellent for large SPS systems
- Most cost-efficient long term
- Automatically maintains calcium and alkalinity once tuned
Kalkwasser (Calcium Hydroxide)
- Added through top-off water
- Helps stabilize pH
- Often used as a supplement alongside other dosing systems
Lighting Requirements
Acropora require high-intensity lighting to thrive. They host symbiotic algae called zooxanthellae which perform photosynthesis and provide much of the coral’s energy.
Insufficient light often results in browning, slow growth, or tissue loss.
Recommended lighting:
PAR: 200 to 450+ PAR at coral placement
Spectrum: Strong blue spectrum around 420 to 450nm enhances fluorescence while balanced white supports growth
Photoperiod: 10 to 12 hours total light
Light Acclimation
Never place a new Acropora frag directly under intense lighting.
New corals should be acclimated by:
- Placing them low in the tank initially
- Gradually moving them upward
- Increasing light intensity over 2 to 4 weeks
Sudden exposure to strong light can cause bleaching or tissue stress.
Flow Requirements
Acropora require strong, chaotic, randomized water movement.
On natural reefs they experience constant surge, wave action, and turbulence.
Poor flow can lead to:
- Tissue necrosis from detritus buildup
- Reduced gas exchange
- Algae growth at the base of colonies
- Dead zones within coral branches
Recommended flow is approximately 50 to 100 times tank turnover per hour.Flow should be randomized and turbulent rather than a constant directional stream.
Popular equipment includes:
- Ecotech Vortech pumps
- Maxspect Gyre systems
- Tunze Turbelle pumps
- Jebao wavemakers
Running pumps in random or pulse modes helps replicate natural reef conditions.
Feeding Acropora
Although most of their energy comes from photosynthesis, Acropora can benefit from supplemental feeding.
Common foods include:
Amino Acids
Products such as Acropower provide dissolved nutrients absorbed through coral tissue and may enhance color and polyp extension.
Coral Foods
Powder foods such as Reef Roids can stimulate feeding responses and may encourage faster growth.
Phytoplankton
Supports microfauna and plankton populations within the reef ecosystem.
Feeding two to three times per week can improve coloration and growth, particularly in nutrient-controlled SPS systems.
Common Problems and Solutions
Rapid Tissue Necrosis (RTN)
RTN causes tissue to rapidly peel away from the skeleton, sometimes within hours.
Common triggers include:
- Alkalinity swings
- Temperature spikes
- Physical damage
- Bacterial infections
Response:
- Frag healthy sections above the necrotic area
- Dip frags in Coral RX or iodine-based dips
- Remove affected colonies if necessary
Brown Out
When stressed, Acropora may appear brown due to increased zooxanthellae density.
Common causes include:
- Elevated nutrients
- Insufficient lighting
- Temperature instability
Correction:
- Increase light gradually
- Maintain stable parameters
- Reduce excess nutrients slowly
Acropora Eating Flatworms (AEFW)
AEFW are among the most serious pests affecting SPS corals.
Signs include:
- White bite marks on coral tissue
- Reduced polyp extension
- Egg clusters on the underside of branches
Treatment typically includes:
- Coral dipping such as Bayer or Coral RX
- Manual egg removal
- Quarantine procedures
Some wrasses may help reduce populations, although they are not a guaranteed solution.
Fragging Acropora
Fragging is an important part of SPS reef keeping and coral propagation.
Typical fragging process:
- Use bone cutters or a coral saw to remove a 1 to 2 inch branch
- Dip the frag in Coral RX or Reef Dip for 10 to 15 minutes
- Attach the frag to a plug with cyanoacrylate gel glue
- Place the frag in moderate light and flow
- Allow two to four weeks for encrusting and healing
Fragging allows hobbyists to propagate colonies, trade corals, and preserve rare strains.
Is Your Tank Ready for Acropora?
Before adding Acropora, ask yourself:
✔ Is my tank at least 6 months old with stable parameters?
✔ Am I testing alkalinity several times per week?
✔ Do I have adequate flow and strong lighting?
✔ Can my system maintain stable calcium and alkalinity?
✔ Do I have effective nutrient control and filtration?
If you answered yes to all of these questions, your system may be ready for Acropora.
Disclaimer: This content is intended for educational purposes only. Information may change as reefing practices evolve and new data becomes available. First Due Aquatic Rescue is not responsible for outcomes resulting from the use of this information. Always verify guidance across multiple reputable sources.
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