SPS vs LPS: The Basics
If you've spent any time in the reef aquarium hobby, you've heard the terms SPS and LPS thrown around constantly. But what do they actually mean, and why does it matter for your tank?
- SPS (Small Polyp Stony): Corals with a hard calcium carbonate skeleton and small, tightly packed polyps. Examples include Acropora, Montipora, Stylophora, and Pocillopora.
- LPS (Large Polyp Stony): Corals with a hard skeleton but large, fleshy polyps. Examples include Torch Corals, Hammer Corals, Octospawn, Acans, Blastos, Chalice, and Favia.
There's also a third category — Soft Corals (Softies) — which have no hard skeleton at all. Mushroom corals, Zoanthids, and Leathers fall into this group.
Difficulty Level
This is the most important practical difference for most reefers:
- SPS: Generally considered the most demanding. They require pristine, stable water chemistry, high flow, and intense lighting. Even small parameter swings can cause rapid tissue necrosis (RTN) or slow tissue necrosis (STN). Best suited for experienced reefers with mature, stable systems.
- LPS: Moderate difficulty. They need stable parameters but are more forgiving than SPS. Many LPS — like Torch Corals, Hammers, and Octospawn — are excellent choices for intermediate reefers.
- Softies: Most beginner-friendly. Mushrooms and Zoanthids can handle a wider range of conditions and are great starting points.
Water Parameters: SPS vs LPS
| Parameter | SPS | LPS |
|---|---|---|
| Alkalinity (dKH) | 8–10 (ultra-stable) | 8–10 (stable) |
| Calcium (ppm) | 420–450 | 380–450 |
| Magnesium (ppm) | 1300–1500 | 1350–1500 |
| Nitrate (ppm) | 1–5 (low) | 5–20 (moderate OK) |
| Phosphate (ppm) | <0.05 | 0.05–0.1 |
The biggest practical difference: SPS demand ultra-low nutrients, while LPS are more tolerant of moderate nutrient levels. Running a mixed reef with both can be a balancing act.
Lighting Requirements
- SPS: High PAR — typically 200–400+ PAR depending on the species. Acropora especially need intense light to grow and color up. They're usually placed at the top of the rockwork.
- LPS: Low to moderate PAR — typically 50–200 PAR. Most LPS do best in the lower half of the tank, away from the most intense light.
This is why mixed reef tanks are often aquascaped with SPS at the top and LPS lower down — a natural light gradient that suits both.
Flow Requirements
- SPS: High, random, turbulent flow. Acropora in particular need strong flow to deliver nutrients and remove waste from their tiny polyps.
- LPS: Low to moderate, indirect flow. Strong direct flow will cause LPS to retract and stress. Gentle, random flow that makes the tentacles sway is ideal.
Aggression
Both SPS and LPS can be aggressive, but in different ways:
- SPS: Generally less aggressive, but can chemically inhibit nearby corals through allelopathy (chemical warfare). Some SPS will overgrow neighbors.
- LPS: Many LPS have long sweeper tentacles that sting neighboring corals at night. Torch Corals, Hammers, and Octospawn are notorious for this. Always leave adequate space between LPS and other corals.
Which Should You Start With?
Our honest recommendation:
- New reefer (0–1 year): Start with softies — Mushrooms, Zoanthids, and Leathers. Get your parameters stable and learn your system.
- Intermediate reefer (1–3 years): Add LPS — Torch Corals, Hammer Corals, Octospawn, Acans, and Blastos are rewarding and achievable.
- Experienced reefer (3+ years, stable system): Venture into SPS — start with hardier species like Montipora and Stylophora before tackling Acropora.
Shop by Coral Type
Browse our collections by coral type to find the perfect addition to your reef: