Hard Corals vs Soft Corals: How to Choose the Right Coral for Your Reef Tank

Hard corals and soft corals are both beautiful parts of the reef aquarium hobby, but they are not the same animals from a care perspective. In our experience at Extreme Corals, understanding the difference between hard and soft aquarium corals is one of the most important lessons a reef keeper can learn. It affects coral placement, lighting, flow, feeding, water chemistry, growth expectations, aggression, and even which corals should be added first to a new reef tank.

Many hobbyists start by choosing corals based on color alone. That is understandable because corals are what make reef tanks so visually exciting. But color is only one part of success. A soft coral, an LPS coral, and an SPS coral may all look great in a photo, but they often need very different environments. A coral that thrives in one tank may struggle in another if it is placed in the wrong light, wrong flow, or wrong water chemistry.

Here at Extreme Corals, we have personally selected, photographed, shipped, and cared for hundreds of thousands of live corals over the years. One thing we have learned is that successful reef keeping starts with knowing what kind of coral you are buying. This guide explains the difference between hard corals and soft corals, how LPS and SPS corals fit into the hard coral category, what each coral group needs, and how to choose the right corals for your reef tank.

If you are comparing coral types for your aquarium, you may also want to browse our LPS corals, SPS corals, soft corals, and our main coral care guide.

What Is the Main Difference Between Hard and Soft Corals?

The main difference is structure. Hard corals build a calcium carbonate skeleton. Soft corals do not build the same large, rigid reef-building skeleton. That structural difference changes almost everything about how these corals grow, how they respond to water chemistry, and how they are placed in a reef aquarium.

Hard corals use calcium and carbonate from the water to build skeletons. This is why calcium, alkalinity, and magnesium are so important in reef tanks that contain LPS and SPS corals. Hard corals can become major reef-building animals in nature, and in aquariums they create structure, growth, and permanent skeletons over time.

Soft corals generally have more flexible bodies and do not create the same heavy stony skeleton. Many contain tiny internal support structures called sclerites, but they do not build reef framework the same way stony corals do. This often makes soft corals more forgiving for newer reef keepers, although they still need good water quality, lighting, and flow.

Hard Corals: The Reef-Building Corals

Hard corals are often called stony corals because they build a hard skeleton from calcium carbonate. In nature, these skeletons are a major part of what forms coral reefs over time. When generations of hard corals grow, die, and are built upon by new coral growth, they help create the physical structure of reef ecosystems.

In home aquariums, hard corals are usually divided into two major groups: LPS corals and SPS corals. Both are stony corals, but they often require different care strategies.

Hard corals are important because they:

• Build calcium carbonate skeletons
• Create permanent structure as they grow
• Use calcium, alkalinity, and magnesium from the water
• Often require more stable chemistry than many soft corals
• Can become showpiece colonies in mature reef tanks
• Include many of the most popular reef aquarium corals

In our experience, hard corals reward consistency. They are not impossible to keep, but they do not respond well to constant parameter swings, poor flow, neglected testing, or unstable salinity.

Soft Corals: Flexible, Forgiving and Full of Movement

Soft corals are often the entry point for many reef keepers because they are generally more forgiving than demanding SPS corals and many delicate fleshy LPS corals. They can add motion, texture, and color without requiring the same calcium and alkalinity demand as fast-growing stony corals.

Common soft corals include:

• Leather corals
• Green Star Polyps
• Pulsing Xenia
• Kenya Tree corals
• Clove polyps
• Many mushroom corals are often grouped with soft coral-style reef keeping

Soft corals are popular because they can bring a natural reef look to the aquarium. Many sway in the current, grow into soft colonies, and tolerate slightly more nutrient availability than some stony corals. They can be excellent for beginner reef tanks, nano reefs, and aquariums focused on motion rather than rigid skeleton structure.

That does not mean soft corals can be ignored. Some soft corals grow quickly, release chemical compounds, or spread onto rockwork where you may not want them long term. A coral can be easy and still require planning.

LPS Corals: Large Polyp Stony Corals

LPS corals are hard corals with larger, fleshier polyps. These are some of the most popular corals we sell because they combine color, movement, feeding behavior, and showpiece appeal. Many LPS corals are easier than SPS corals when kept in stable tanks, but they can still be sensitive to tissue damage, direct flow, and poor placement.

Popular LPS corals include:

• Hammer Corals
• Torch Corals
• Frogspawn Corals
• Favia and Favites
• Scolymia
• Trachyphyllia
• Acanthophyllia
• Lobophyllia
• Chalice corals

LPS corals often do best with moderate lighting, moderate indirect flow, stable water chemistry, and enough spacing from neighboring corals. Many have fleshy tissue that can be damaged by sharp rock or strong direct current. Some also have sweeper tentacles and can sting nearby corals.

At Extreme Corals, we often recommend LPS corals to reef keepers who want more color and movement after they have learned the basics. A healthy LPS coral can become the centerpiece of a tank, but it should be placed with its mature size and aggression in mind.

SPS Corals: Small Polyp Stony Corals

SPS corals are hard corals with smaller polyps and usually more demanding care requirements. They are known for branching, plating, tabling, and encrusting growth forms. SPS corals can create the classic reef-building look many hobbyists dream about, but they usually require stronger lighting, stronger indirect flow, and much tighter water stability than most soft corals.

Popular SPS corals include:

• Acropora
• Montipora
• Birdsnest-style corals
• Stylophora
• Pocillopora

SPS corals often need:

• Strong reef lighting
• High, indirect, turbulent flow
• Stable alkalinity
• Controlled nitrate and phosphate
• Consistent calcium and magnesium
• A mature reef tank with steady maintenance habits

In our experience, SPS corals are not the best first corals for most brand-new reef keepers. They can be extremely rewarding, but they expose weaknesses in husbandry quickly. If alkalinity swings, salinity drifts, or nutrients bottom out, SPS corals often show stress before easier corals do.

Hard Coral vs Soft Coral Care Requirements

Hard and soft corals share some basic needs. Both need appropriate saltwater, lighting, flow, stable temperature, and clean conditions. The difference is how sensitive they are to certain details and how much mineral demand they place on the system.

The safest approach is to choose corals based on the tank you have now, not the tank you hope to have later. A stable soft coral or LPS tank can be much more successful than an SPS tank rushed before the system is ready.

Water Parameters for Hard and Soft Corals

All reef corals need stable saltwater, but hard corals usually make calcium, alkalinity, and magnesium more important because they build skeletons. Soft corals still benefit from stable chemistry, but they usually do not consume calcium and alkalinity at the same rate as fast-growing stony corals.

For hard corals, especially SPS corals, alkalinity swings can cause serious stress. For soft corals, nutrient balance and flow often have a major impact on fullness and growth. For mixed reefs, the challenge is finding a stable middle ground that supports several coral groups at once.

For a deeper chemistry breakdown, review our reef tank water parameters guide.

Lighting Differences Between Hard and Soft Corals

Lighting needs vary by coral type, but there are some practical patterns. Many soft corals and fleshy LPS corals do well under low to moderate lighting. Many SPS corals need stronger lighting after proper acclimation.

General lighting guidance:

• Soft corals: Often low to moderate light, depending on the species.
• LPS corals: Often moderate light, with fleshy sandbed corals usually needing less intensity.
• SPS corals: Often stronger light with careful acclimation and stable nutrients.

One of the most common mistakes we see is putting every coral under strong lighting because the colors look brighter. That can hurt lower-light corals. A coral does not need to be blasted with light to be healthy. Proper light is better than maximum light.

For more detail on PAR, spectrum, and light acclimation, read our reef tank lighting guide.

Water Flow Differences Between Hard and Soft Corals

Flow is one of the most important differences between coral groups. SPS corals often need strong, random, indirect flow to remove waste and deliver nutrients. Many LPS corals need moderate indirect flow, but their fleshy tissue can be damaged by direct blasts. Many soft corals like gentle to moderate movement.

General flow guidance:

• Soft corals: Gentle to moderate flow, enough to move tissue without forcing it closed.
• LPS corals: Moderate indirect flow for many species; gentle flow for very fleshy corals.
• SPS corals: Stronger indirect, turbulent flow to prevent detritus buildup and support growth.

In our experience, many coral problems are flow problems disguised as something else. A Hammer Coral that will not open may be getting blasted. A mushroom that detaches may be in too much flow. An SPS coral with detritus buildup may not have enough flow. Matching flow to coral type is critical.

Our water flow and coral health guide explains how to build better flow zones.

Feeding Hard Corals and Soft Corals

Many corals are photosynthetic, but that does not mean they all feed the same way. LPS corals often respond well to occasional meaty foods or LPS pellets. Soft corals may absorb dissolved nutrients or fine suspended foods. SPS corals often rely on light, dissolved nutrients, fish waste, and fine planktonic foods.

Feeding examples:

• LPS corals: Mysis shrimp, small pellets, finely chopped marine foods, and zooplankton-based coral foods.
• Soft corals: Dissolved nutrients, fine foods, phytoplankton-style foods when appropriate, and nutrients from fish feeding.
• SPS corals: Fine particle foods, stable nutrients, amino acids used carefully, and strong light-driven energy.

Feeding should support the system, not pollute it. Overfeeding can create algae and nutrient problems. Underfeeding or stripping nutrients too low can make corals pale and thin. Balance matters.

Which Corals Are Best for Beginners?

For most beginners, soft corals and hardy LPS corals are better starting points than demanding SPS corals. A new reef keeper should learn salinity stability, basic testing, lighting, flow, and maintenance before jumping into more sensitive coral groups.

Good beginner coral options may include:

• Zoanthids
• Mushroom corals
• Ricordea mushrooms
• Leather corals
• Green Star Polyps on isolated rock
• Duncan Coral
• Some hardy LPS corals in stable tanks

Beginner-friendly does not mean no-care. It means the coral is more forgiving while the reef keeper learns. Start with corals that match your tank, then move into more demanding pieces as your system matures.

Browse soft corals, Zoanthids, and Ricordea mushrooms if you are building a beginner-friendly reef tank.

Which Corals Are Best for Experienced Reef Keepers?

Experienced reef keepers often enjoy more demanding LPS and SPS corals because they require more precision and provide more advanced growth forms, coloration, and aquascaping options.

Advanced coral choices may include:

• Acropora
• High-end Montipora
• Chalice corals
• Showpiece Scolymia
• Acanthophyllia
• Premium Euphyllia corals
• Wellsophyllia and other fleshy open brain corals

These corals can be very rewarding, but they should be added to a tank that is ready. Stability matters more than excitement. The more expensive the coral, the more important it is to match the animal to the system.

Coral Aggression: Hard Corals vs Soft Corals

Coral aggression is another major difference between coral groups. Many LPS corals can sting nearby corals with sweeper tentacles or aggressive tissue contact. Some soft corals may spread quickly or compete chemically. SPS corals can shade or overgrow neighbors as colonies mature.

Common aggression issues include:

• Torch Corals stinging nearby LPS or soft corals
• Chalice corals damaging neighbors at night
• Galaxea extending long sweepers
• Soft corals spreading across rockwork
• Green Star Polyps overtaking nearby surfaces
• SPS colonies shading lower corals
• Mushrooms crowding slower-growing corals

Spacing is not wasted space. It is part of coral care. A small frag can become a large colony, and a peaceful-looking coral may be more aggressive after dark. For more help, read our coral aggression guide.

How Hard and Soft Corals Grow Over Time

Hard and soft corals grow differently. Hard corals build skeletons, add new heads, branch, plate, encrust, or expand over their calcium carbonate base. Soft corals may spread by budding, attaching to new areas, growing stalks, or covering rockwork.

Growth expectations matter because the coral you buy today will not stay the same size forever. A small soft coral can spread across rockwork. A branching Hammer Coral can become a colony. An SPS frag can shade lower corals. A chalice can send sweepers into nearby space.

When placing corals, think six months to two years ahead. Ask:

• How large will this coral become?
• Will it sting nearby corals?
• Will it spread onto rockwork?
• Will it shade corals below it?
• Will it need more calcium and alkalinity as it grows?

Planning for growth is one of the biggest differences between a reef tank that matures beautifully and one that becomes crowded and difficult to manage.

Mixed Reef Tanks: Keeping Hard and Soft Corals Together

Many reef keepers want a mixed reef with soft corals, LPS corals, and SPS corals in the same aquarium. This can work very well, but it requires careful placement and stable middle-ground conditions.

A successful mixed reef needs:

• Moderate nutrients that are not too high or too low
• Different lighting zones for different corals
• Different flow zones throughout the aquascape
• Spacing for LPS aggression
• Growth control for fast-spreading soft corals
• Stable alkalinity for stony corals
• Regular observation as colonies mature

Mixed reefs are beautiful because they combine movement, structure, color, and texture. But they are not successful by accident. The reef keeper has to build zones and place each coral where it belongs.

How to Choose Between Hard Corals and Soft Corals

The best coral choice depends on your tank and your goals. Do not choose hard or soft corals just because one group sounds easier or more advanced. Choose based on what your aquarium can support.

Choose soft corals if:

• You are newer to reef keeping.
• You want movement and forgiving care.
• Your tank has moderate nutrients.
• You want lower-maintenance coral options.
• You are comfortable managing possible spreading growth.

Choose LPS corals if:

• You want color, movement, and larger fleshy polyps.
• Your tank has stable salinity and alkalinity.
• You can provide moderate light and indirect flow.
• You can give corals room for expansion and sweepers.
• You want showpiece corals without SPS-level difficulty.

Choose SPS corals if:

• Your tank is mature and stable.
• You can maintain alkalinity consistently.
• You have strong lighting and strong indirect flow.
• You can control nutrients without stripping them to zero.
• You enjoy precision reef keeping and long-term growth.

There is no shame in choosing easier corals. A thriving soft coral or LPS tank is far better than a struggling SPS tank rushed before it is ready.

Our Practical Approach at Extreme Corals

Here at Extreme Corals, we look at coral care from the viewpoint of long-term success. We want the coral to survive shipping, open in the customer’s tank, adapt to the aquarium, and continue growing. That means the right coral needs to go into the right system.

Our practical advice is:

• Start with corals that match your current tank.
• Do not buy SPS until your tank is stable enough for SPS.
• Do not blast fleshy LPS corals with direct flow.
• Use isolated rocks for soft corals that spread quickly.
• Keep alkalinity stable for hard corals.
• Keep nutrients measurable but controlled.
• Give every coral enough room to grow.
• Choose health over color alone.

That last point matters. A bright coral that is already stressed is not a better purchase than a healthy coral with strong tissue and appropriate placement potential.

Related Coral Categories and Guides

If you are comparing hard and soft corals, these related categories and guides can help you choose better corals for your reef tank:

• LPS Corals - Browse large polyp stony corals for movement, color, and showpiece appeal.
• SPS Corals - Explore small polyp stony corals for structure and advanced reef tanks.
• Soft Corals - Browse flexible, forgiving corals for soft coral and mixed reef systems.
• Zoanthids - Add colorful polyps to your reef aquarium.
• Ricordea Mushrooms - Explore colorful mushroom corals for lower-light zones.
• Coral Placement Guide - Learn how light, flow, spacing, and growth affect coral placement.
• Coral Aggression Guide - Understand sweeper tentacles, spacing, and coral competition.
• New Arrival Corals - See recently added corals for your reef tank.

Shop Hard Corals and Soft Corals

Hard corals and soft corals both have a place in reef aquariums. Soft corals offer movement, forgiving care, and natural texture. LPS corals offer color, fleshy polyps, feeding behavior, and showpiece appeal. SPS corals offer structure, growth forms, and the classic reef-building look for more advanced systems.

The right choice depends on your tank’s stability, lighting, flow, nutrients, and your experience level. Browse LPS corals, SPS corals, soft corals, Zoanthids, Ricordea mushrooms, and Scott's Handpicked Corals at ExtremeCorals.com to find healthy corals that fit your reef tank.

Frequently Asked Questions About Hard and Soft Corals

What is the difference between hard and soft corals?

Hard corals build calcium carbonate skeletons, while soft corals do not build the same large rigid skeleton. This affects growth, placement, water chemistry needs, and care requirements.

Are LPS corals hard corals?

Yes, LPS corals are hard corals. They build stony skeletons but have larger, fleshier polyps than SPS corals.

Are SPS corals hard corals?

Yes, SPS corals are hard corals with smaller polyps. They often need stronger lighting, stronger indirect flow, and more stable water chemistry than many other coral groups.

Are soft corals easier than hard corals?

Many soft corals are easier and more forgiving than hard corals, especially for beginners. However, some soft corals can spread quickly or compete chemically, so they still need planning.

Which corals are best for beginners?

Many beginners do well with soft corals, Zoanthids, mushroom corals, Ricordea, Green Star Polyps on isolated rock, and some hardy LPS corals in stable tanks.

Do hard corals need calcium?

Yes, hard corals use calcium and carbonate to build their skeletons. Calcium, alkalinity, and magnesium should be monitored in tanks with stony corals.

Can hard and soft corals live together?

Yes, hard and soft corals can live together in mixed reef tanks if lighting, flow, nutrients, spacing, and chemical competition are managed carefully.

Do soft corals need strong light?

Most soft corals do not need extremely strong light. Many do well under low to moderate reef lighting, depending on the species and tank conditions.

Are SPS corals harder than LPS corals?

In general, SPS corals are more demanding than many LPS corals because they often require stronger lighting, stronger flow, tighter nutrient control, and more stable alkalinity.

Should I start with soft corals or hard corals?

Most new reef keepers should start with soft corals, Zoanthids, mushrooms, or hardy LPS corals before moving into more demanding SPS corals.

About the Author

Scott Shiles is the owner of ExtremeCorals.com, which he has operated for over 25 years and is recognized as one of the early dedicated live coral websites on the internet. A lifelong reef keeper since 1984, Scott has decades of hands-on experience maintaining marine aquariums and previously owned and operated a brick and mortar aquarium retail store for 10 years, including five years alongside Extreme Corals. He holds a degree in Marine Biology and has personally selected and sold hundreds of thousands of live corals. An avid scuba diver who has explored reef systems around the world, Scott shares practical coral care and husbandry knowledge based on real world reef experience.