Basics & Overview
The Hammer coral is a Large-Polyp Stony (LPS) coral.
Scientific name: Euphyllia ancora.
They come in wall type and branching type morphologies. Branching types tend to grow faster.
Care difficulty is moderate — easier than some SPS corals, but they still need attention to detail.
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Tank Conditions
Light
Moderate lighting is sufficient. Aim for ~80-150 PAR (some sources say up to ~250 PAR for brighter varieties).
They often do well in mid to lower parts of the tank (unless your lighting is very weak).
Avoid intense, direct light (especially for wall types) until you know how your specimen responds.
Water Flow
Moderate, indirect flow is best. The polyps should gently sway but not be blasted or constantly bent over by current.
Too much flow → polyp retraction, damage to tissues. Too little flow → detritus can settle, poor health.
Water Chemistry Parameters
Temperature: ~74-78 °F (23-26 °C) recommended. Some guides list up to ~84 °F as upper limit, but lower end is safer.
pH: ~8.0-8.4 (aim ~8.2-8.3)
Salinity: ~1.024-1.026 specific gravity (≈35 ppt)
Alkalinity: ~8-12 dKH. Many aim ~9 dKH.
Calcium: ~350-450 ppm. (~400 ppm is ideal)
Magnesium: ~1200-1350 ppm
Nitrate: ideally <10 ppm or around 5-10 ppm.
Phosphate: low – <0.1 ppm recommended.
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Placement & Compatibility
Choose a spot with moderate light and flow. For weaker lighting, place higher; for stronger lighting, lower placement works.
Give them room! They have long sweeper tentacles and are aggressive towards other corals. Keep 3-4 inches (or more) away from neighbors unless they’re other Euphyllia.
They can be kept near other Hammer/torch/frogspawn corals (same genus) more safely.
Avoid placing directly on sand bed if flow is too weak; detritus build-up can cause problems.
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Feeding & Nutrition
Hammer corals are photosynthetic (thanks to zooxanthellae), so the light + good water conditions cover most of their needs.
They can benefit from occasional feeding of meaty foods (e.g., mysis shrimp, brine shrimp) to boost growth and color.
Feed a couple of times per week is sufficient; over-feeding can lead to bad water quality.
If you feed, turn off main flow temporarily, aim food with a turkey baster or pipette near the polyps.
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Common Issues & Troubleshooting
Tissue recession: Could be due to poor water parameters (esp calcium/alkalinity), too high flow, too strong lighting, or neighboring coral aggression.
Bleaching: Too high light or sudden change in lighting. Move to gentler area, acclimate.
Polyp not extending: Check flow and light — maybe it's too strong, or water quality is off.
Aggression damage: If placed too close to other corals, sweeper tentacles may sting nearby colonies. Give ample space.
General sensitivity: The genus Euphyllia is more tolerant than many SPS, but still dislikes rapid fluctuations in water chemistry. Stability is key.
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Growth, Fragging & Long-Term Care
Growth rate is moderate to slow. Branching types will show faster growth and are easier to frag.
You can frag by cutting off a branch (branching type) or using a Dremel for wall types. Dip corals post-cut to reduce infection.
Maintain stable chemistry; when you have many stony corals (including Hammer), demand for calcium and alkalinity increases. Monitor and supplement accordingly.
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Quick Reference Chart
Parameter Target Range
Light ~80-150 PAR (moderate)
Flow Moderate, indirect
Temperature ~23-26 °C (74-78 °F)
pH ~8.1-8.4
Salinity ~1.024-1.026
Alkalinity ~8-12 dKH
Calcium ~350-450 ppm (ideal ~400 ppm)
Magnesium ~1200-1350 ppm
Nitrate <10 ppm (5-10 ppm ideal)
Phosphate <0.10 ppm
