Soft coral vs LPS vs SPS reef comparison
Choosing between Soft and LPS reefs and SPS-dominant reefs is a fit decision, not a lab result: tank size, reef goal, budget tier, failure mode, and upgrade path decide which one belongs in the build.
SPS vs LPS: what actually differs
Both SPS (small polyp stony) and LPS (large polyp stony) corals build calcium carbonate skeletons. SPS such as Acropora, Montipora and Pocillopora have tiny polyps on branching or plating skeletons. LPS such as hammer, torch, frogspawn and brain corals have large fleshy polyps and can take food directly.
In practice SPS ask for more light, stronger and more random flow, and tighter alkalinity stability. LPS tolerate a wider range but still react to rapid swings, and they need space because many sting their neighbors. Soft corals (mushrooms, zoanthids, leathers) are the most forgiving of the three.
| Need | Soft corals | LPS | SPS |
|---|---|---|---|
| Light at the coral (PAR) | 50–150 (ReefCrafter band) | 75–200 | 200–450; Acropora toward 300–450 |
| Total flow (× tank volume per hour) | Low to moderate | 10–25×, gentle and indirect | 20–50×, strong and variable |
| Alkalinity target | Stable, no dosing focus at first | 7–11 dKH; keep within ~1 dKH day to day | 7.5–9 dKH; keep within ~0.5 dKH day to day |
| Beginner fit | Best first corals | Good next step | Best after the tank has stability history |
LPS and SPS figures from Tankly's LPS care, SPS care and SPS vs LPS guides; the soft-coral PAR band is the one ReefCrafter's lighting calculator uses. Individual species vary; check each coral's own page.
Choose Soft and LPS reefs when
- Beginners who want forgiving coral choices, lower equipment pressure, and a slower ramp into reef chemistry.
- Nano and mid-size tanks where stability margins are still developing and the first goal is confidence.
- Builds where budget should go toward complete basics before high-output lighting, dosing, and premium flow.
Choose SPS-dominant reefs when
- Experienced keepers ready for stronger lighting, higher varied flow, tighter nutrient control, and dosing discipline.
- Mature systems with proven salinity, alkalinity, temperature, and nutrient stability.
- Reefers who understand that SPS is a full stability stack, not simply a coral category.
Fit math
- Match the coral goal to PAR, flow turnover, nutrient export, testing cadence, and maturity before shopping livestock.
- Soft and LPS plans tolerate wider margins; SPS plans narrow the acceptable range for light, flow, and chemistry.
- Use the planner when changing goals because one coral decision can force different lights, pumps, dosing, and patience.
Common questions
Is SPS or LPS easier for beginners?
LPS. They tolerate a wider alkalinity range (about 7–11 dKH) and moderate light (about 75–200 PAR). SPS generally need 200+ PAR, 20–50× flow and alkalinity held within about 0.5 dKH day to day.
Can SPS and LPS live in the same tank?
Yes, in a mixed reef with zones: SPS high in the rockwork under strong flow, LPS lower with gentler indirect flow and room so their sweeper tentacles cannot reach neighbors.
What does SPS stand for?
Small polyp stony coral. LPS stands for large polyp stony coral.
Risks before buying
- Buying SPS before the tank has stability history often exposes weak lighting, flow, dosing, or nutrient control.
- Soft corals and LPS can still fail when salinity swings, direct flow, or aggressive neighbors are ignored.
- A mixed reef needs zones; one equipment setting rarely satisfies every coral equally.