What is the difference between SPS and LPS coral?

Short answer

SPS (small-polyp stony) coral has small polyps over a calcium-carbonate skeleton (acropora, montipora, stylophora). LPS (large-polyp stony) coral has large fleshy polyps over a heavier skeleton (euphyllia, goniopora, acanthastrea, lobophyllia). SPS demands stable parameters, intense light, and high flow. LPS is more parameter-tolerant, needs moderate light and flow, and benefits from feeding.

In depth

The SPS/LPS distinction is the central organizing principle of stony coral keeping. The "small" vs "large" refers to polyp size relative to the skeleton, but the practical implications run far deeper than visual differences.

SPS characteristics

Small polyps (1-5mm typically) covering a continuous calcium-carbonate skeleton
Branching, plating, encrusting, or table growth forms
Intense light requirements (200-450 PAR depending on species)
High flow requirements (20-60x tank turnover, turbulent rather than laminar)
Photoautotrophic - derives 80%+ of energy from photosynthesis via zooxanthellae
Demands rock-stable alkalinity (within 0.3 dKH), calcium (within 20 ppm), magnesium (within 50 ppm)
Examples: acropora, montipora, stylophora, pocillopora, seriatopora

LPS characteristics

Large polyps (1-10cm) covering a heavier, more visible skeleton
Fleshy tissue extending dramatically when healthy
Moderate light requirements (100-200 PAR)
Moderate flow (10-20x turnover, no direct laminar flow on polyps)
Mixotrophic - photosynthesizes for energy AND captures food particles for growth
Tolerates wider parameter swings than SPS
Examples: euphyllia (hammer, torch, frogspawn), goniopora, acanthastrea, lobophyllia, trachyphyllia, catalaphyllia, plerogyra

Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.