LPS, SPS, and Soft Corals in Practice
LPS, SPS, and Soft Corals in Practice
This article picks up where the basics article leaves off. If you’re new to corals, start there. Here we go into concrete numbers, placement logic, managing allelopathy, and the compromises involved in keeping multiple groups together.
Parameters by Group
What all groups share: alkalinity, calcium, and magnesium are the fundamental elements all corals use to build their skeletons. The differences show up mainly in nutrient concentrations and how tight a stability is required.
Soft Corals
Soft corals are the most tolerant group. They accept a wider range of parameter variation than LPS or SPS, and many species actually thrive in tanks where nutrient levels are higher than the other groups prefer.
| Parameter | Typical range |
|---|---|
| Alkalinity | 7–10 dKH |
| Calcium | 380–450 ppm |
| Magnesium | 1250–1400 ppm |
| Nitrate | 5–25 ppm |
| Phosphate | 0.05–0.3 ppm |
| Temperature | 25–27 °C |
| Salinity | 1.025–1.026 |
Note: high nutrients won’t harm soft corals, but they create favorable conditions for algae growth. Balance still matters.
LPS
LPS requires more stable parameters than soft corals but is considerably more forgiving than SPS. Euphyllia in particular tolerates moderate variation, while brain corals and Trachyphyllia can be more sensitive.
| Parameter | Typical range |
|---|---|
| Alkalinity | 7.5–9 dKH |
| Calcium | 400–450 ppm |
| Magnesium | 1300–1400 ppm |
| Nitrate | 2–10 ppm |
| Phosphate | 0.02–0.1 ppm |
| Temperature | 24–26 °C |
| Salinity | 1.025–1.026 |
LPS corals are most sensitive to rapid alkalinity swings. Changes under 0.5 dKH/day are safe — larger shifts can cause tissue retraction or RTN in sensitive species.
SPS
SPS is the most demanding group. Parameter stability is as important as the absolute level — SPS doesn’t suffer so much from alkalinity being 7 dKH or 8 dKH, but from swinging between the two day to day. Intra-day variation above 0.5 dKH is already a significant stressor.
| Parameter | Typical range |
|---|---|
| Alkalinity | 7–8 dKH (stable) |
| Calcium | 400–450 ppm |
| Magnesium | 1300–1400 ppm |
| Nitrate | 0.5–5 ppm |
| Phosphate | 0.02–0.05 ppm |
| Temperature | 25–26 °C |
| Salinity | 1.025–1.026 |
In ultra-low nutrient systems (ULNS), nitrate can be practically undetectable and phosphate below 0.02 ppm. In these conditions corals need active amino acid and organic supplementation to meet their energy needs — otherwise they start to “starve” and lose coloration.
Placement in the Tank
Light
The general rule: SPS up high, LPS in the middle, soft corals where they fit. More specifically:
SPS needs high PAR — typically 200–400+ µmol/m²/s depending on species. Acropora is generally placed in the upper third. Montipora plates can tolerate somewhat less (150–250) and are a good choice for mid-level placement.
LPS does well in moderate light, typically 50–150 PAR. Euphyllia can go lower; Goniopora a little higher. Trachyphyllia lives naturally on sandy flats and needs low light — it doesn’t belong on top of rocks.
Soft corals vary considerably. Zoanthids tolerate a wide PAR range and are often placed on rocks at various levels. Leather corals can manage in low light but grow slowly.
Flow
SPS needs strong, multidirectional flow. Acropora suffers in weak flow — detritus accumulates between branches and can cause tissue damage. The goal is an even, wave-like motion, not a direct jet.
LPS prefers moderate flow. Euphyllia tentacles can sway gently but shouldn’t constantly fold to extremes — prolonged strong flow causes stress. Brain corals need only gentle movement.
Soft corals are tolerant. Xenia and Anthelia prefer moderate flow. Mushrooms don’t need strong flow and manage well in calmer areas.
Distance from Other Corals
Distance doesn’t mean just physical contact — corals wage chemical warfare through the water column too. More on this in the allelopathy section.
Physical safety distances:
- Euphyllia tentacles can reach 15–20 cm — account for full extension
- Brain corals have shorter mesenterial filaments, but still give 5–10 cm minimum
- Zoanthids can grow over slower-moving corals — monitor growth direction actively
Allelopathy and Aggression
Corals are not passive animals. They compete for space through chemical and physical means — and some species are considerably more aggressive than others. This is covered in detail in the allelopathy articles, but here’s a group-level summary.
Most aggressive: the Euphyllia genus is notoriously aggressive toward other LPS corals. Hammer, frogspawn, and torch are generally compatible with each other (the so-called Euphyllia peace), but their tentacles will kill many other LPS species on contact.
An important note on origin: Indonesia-origin and Australia-origin Euphyllia do not necessarily get along — even within the same species. Individuals of different geographic origin can react aggressively to each other on contact, while specimens from the same origin would coexist peacefully. Always check the coral’s origin at point of sale and keep Euphyllia of different origins well separated.
Soft corals vs. SPS: soft corals release terpene compounds and other chemicals into the water that can slow or damage SPS — leather corals (Sinularia, Sarcophyton) are especially well known for this. In a tank with both soft corals and SPS, activated carbon and regular water changes are important.
Zoanthids: fast-growing and can smother slower-moving corals. Monitor growth and frag as needed.
Feeding by Group
Soft Corals
Most soft corals get enough energy from photosynthesis and don’t need active feeding. Zoanthids and palythoa respond well to small zooplankton portions (e.g., copepods) — feeding can accelerate growth. Xenia doesn’t feed to any meaningful degree.
LPS
LPS benefits clearly from feeding. Tentacles are designed to catch zooplankton, and larger species (Trachyphyllia, Lobophyllia) can handle surprisingly large pieces.
Practical feeding:
- Euphyllia: small zooplankton, Artemia, copepod cultures — 1–2 times per week
- Brain corals: can be target-fed directly to the mouth, even once a week
- Trachyphyllia: feeds actively and accepts small meaty pieces once a week
- Goniopora: sensitive — oversized food portions can cause polyp retraction. Small zooplankton is best.
Don’t feed immediately before or after water changes — let corals eat undisturbed.
SPS
SPS gets most of its energy from zooxanthellae through photosynthesis. Direct feeding isn’t essential, but in ULNS tanks, dosing zooplankton or amino acids can support growth. Overfeeding can raise nutrient levels above SPS’s optimal range.
Common Problems by Group
SPS: RTN and STN
Rapid Tissue Necrosis (RTN) and Slow Tissue Necrosis (STN) are the most feared SPS problems. RTN progresses fast — within hours — and can destroy an entire colony. Common triggers: rapid alkalinity swing, temperature spike, a pest, or mechanical damage. STN progresses more slowly, over days or weeks.
If RTN is spotted: frag the healthy section immediately and dip it — it may survive. The affected portion will not recover.
LPS: Tissue retraction and bleaching
Tissue retracts when a coral is stressed — low alkalinity, wrong flow, neighboring corals. Temporary retraction is normal; sustained retraction is a warning sign. Bleaching (pale coloration) signals the loss of zooxanthellae — usually from excessive temperature or light intensity.
Soft corals: Mucus production and contraction
Soft corals produce mucus under stress or when transitioning between growth and rest phases. Leather corals (Sarcophyton) close periodically for days and shed a white mucus film — this is normal, not disease. Heavy mucus production immediately after moving is a stress response.
Mixed Reef: Keeping All Groups Together
Yes — but compromises are required.
Common approaches:
LPS + soft corals: the most natural combination. Parameters are close, both groups tolerate somewhat elevated nutrients. Watch for allelopathy from soft corals.
LPS + SPS: possible but demanding. SPS needs lower nutrients than LPS prefers. Compromise parameters (nitrate 2–5 ppm, phosphate 0.03–0.06 ppm) work reasonably for both — but neither group is at its optimum. Activated carbon and a good protein skimmer help manage allelopathy.
All three together: a common goal for many hobbyists. It works when placement is thought through (SPS high, LPS low and to the sides, soft corals in separate niches), allelopathy is managed, and parameters are in the compromise zone. Requires the most experience and active monitoring.
What to avoid: placing aggressive soft corals (Sinularia, large Sarcophyton) directly into an SPS-dominant tank without effective carbon filtration. The chemical competition can damage SPS before you even notice the problem.
References
Peer-reviewed research
- Ferrier-Pagès, C., et al. (2011). Physiological response of scleractinian corals to nutrient enrichment. Journal of Experimental Marine Biology and Ecology, 408(1-2), 201–209.
- Rädecker, N., et al. (2015). Nitrogen cycling in corals: the key to understanding holobiont functioning? Trends in Microbiology, 23(8), 490–497.
Literature
- Borneman, E. H. (2001). Aquarium Corals: Selection, Husbandry, and Natural History. T.F.H. Publications.
- Delbeek, J. C., & Sprung, J. (1994). The Reef Aquarium, Vol. 1. Ricordea Publishing.
- Delbeek, J. C., & Sprung, J. (2005). The Reef Aquarium: Science, Art, and Technology, Vol. 3. Ricordea Publishing.
Community resources
- Manta Systems (2025). Amino Acid, Carb & Vitamin Dosing in Reef Tanks. https://www.mantasystems.net/a/blog/post/amino-acids
- Reef2Reef Community. SPS and LPS coral care guides. https://www.reef2reef.com
- Tidal Gardens (2024). Acropora coral care. https://tidalgardens.com/articles/coral-care-articles/acropora-coral-care.html