Live Rock For a Reef Tank – All You Need To Know!

Live Rock is something you will eventually come across as you begin your research into a saltwater aquarium, but what the heck is it? How can rock be alive?

Live Rock is a very beneficial addition to any reef aquarium. It provides large surface areas for Nitrifying Bacteria to colonize & multiply, allows natural food sources to grow and provides shelter for livestock. Using live rock also provides a natural framework for aquascaping and mounting coral.

What makes this stuff seem to be so important in a reef aquarium and why do so many tanks seem to use it? These are all valid questions that will be answered right here!

What Is Live Rock?

Live Rock, in its basic form, is ocean rock and dead coral skeletons that once formed part of a natural coral reef. During storms, these rocks, and dead coral skeletons were washed towards the shore where they begin to receive light from the sun in the shallow water.

This light then encouraged the natural growth of marine invertebrates, organisms, corals, sponges, algae, and bacteria. This ‘Live’ or ‘Rock With Living Things On It’, is then harvested and sent to the stores for use in our hobby.

Live Rock Header
Live Rock

So, in essence, the rock is covered in living organisms that essentially make the rock live. The skeleton of each piece is dead, but its crust is living.

What Is Live Rock Used For?

There are several main reasons why we use it in our reef tanks but by far the main purpose is to provide enormous surface area for Nitrifying Bacteria to colonize and mulitply.

This Nitrifying Bacteria is what forms the backbone of your aquarium’s natural biological filter. Without live rock, in your aquarium, you would have to provide different media for this bacteria to colonize. By using live rock we get the natural look of the reef, provide the aquascape to mount our corals to and give the beneficial bacteria a home.

As well as the main benefits just mentioned here are an abundance of benefits to using live rock in our tanks:

What Are The Benefits of Using Live Rock In A Reef Aquarium?

  • Live Rock was once part of a living coral reef. As it leaches into your water it will return the building blocks used by the coral skeletons back into your water to be consumed by your own coral. This also helps stabilize the Ph of your water.
  • Your live rock is full of diverse marine life, when added to your aquarium it will provide a solid foundation on the rest of your reef to build on.
  • The majority of live rock is very, very porous and this provides massive surface area for your beneficial Nitrosomonas and Nitrobacter Bacteria to colonize to process the harmful Nitrite and Ammonia in your water.
  • Using live rock greatly reduces the time it will take your aquarium to cycle as it is already full of Nitrifying bacteria.
  • Good quality, pre-cured live rock will ensure the minimal amount of pests will enter your aquarium.
  • The many types of rock, sizes, and shapes available give you endless flexibility to create the beautiful aquascape of your choice.
  • Live rock is a natural home to many fish in the wild and it instantly helps to settle new fish that have been wild-caught when they are introduced to your aquarium.
  • Clever use and positioning of live rock can create spaces of lower flow and lower light for corals that require this habitat – A bit of foresight and planning is all that is required.
  • Live rock can help to reduce many of the pest algae that will show up in the early months of a new aquarium. By containing marine algae and organisms they can outcompete any nuisance algae trying to get established.
  • Live rock is a far better biological filter than any product you can purchase for your aquarium.
  • Coralline algae will quickly spread from live rock to other parts of your aquarium giving it a natural look far quicker than a tank without it.
  • Small amounts of live rock can be used to quickly seed dead or dry rock if required.
  • Many facilities now culture their own live rock to reduce the amount removed from the oceans – We all have to do our part on conserving this beautiful planet of ours!
  • To go one step further, you can now purchase ‘Man-Made’ live rock where the rock is man-made but it’s then sat in the ocean or a mature holding facility to allow the marine organisms to colonize each piece.
  • Live rock is available in pretty much every saltwater fish store – Just research its quality before buying!

Even though there are many great benefits to using live rock there are some drawbacks you need to be aware of to help prevent some possible tough times in the future of your aquarium!

Are There Drawbacks of Using Live Rock In A Reef Tank?

  • Uncured live rock can introduce large amounts of ammonia, nitrite, and phosphate into your aquarium that can quickly kill all your livestock – More on curing later!
  • Live rock can introduce many pests hiding deep within it into your aquarium like:
    • Mantis Shrimp
    • Bobbit/Eunice Worms
    • Fireworms
    • Bristleworms
    • Nuisance Algae
    • Aiptasia/Mejanos
  • The quality of live rock is very wide – Use only reputable sources.
  • Wild-Cultured live rock is damaging to the natural eco-system.
  • Live rock is far more expensive compared to dry rock.
  • Live rock has to be kept wet, this increases its shipping weight, thus its shipping cost.
  • Adding un-cured liverock into an established aquarium can cause a tank crash due to the organism die-off that always occurs when live rock is moved from tank to tank. Any air exposure increases the die-off.

As you can see there are many benefits of using live rock compared to its drawbacks, and many of those can be avoided with a small amount of due diligence during your sourcing and purchase.

What is Uncured Live Rock?

This term un-cured refers to rock that has been moved from point A to point B without any form of acclimation.

As I briefly mentioned, when live rock is exposed to air or moved to a foreign body of water, organisms within and on the rock begin to die. As this death occurs they will naturally begin to decay and break down at which point they begin to release toxic ammonia, nitrite, and phosphates into the surrounding water.

Depending on the amount of die-off, the amount of the toxic elements released can be minimal to completely overwhelming. Allowing this die-off to occur in your aquarium will guarantee that you will begin to lose livestock!

How Do You Cure Your Own Live Rock?

This is a simple process and by doing this you are in effect ‘Acclimating’ your new rock to your aquarium. To begin you will need the following items:

  • Container or bin/s with lid’s large enough to house all your purchased rock
  • Small powerhead for each bin to keep the water circulating to prevent dead spots
  • Small heater for each bin set to the same temperature as your aquarium
  • Good quality Ammonia & Nitrite Test kits – I use Salifert
  • Good Quality Salt Mix Granules – I use Instant Ocean
  • Good Quality RO/DI water to fill the container/s
  • Toothbrush
  • Googles
  • Latex Gloves

The process to cure the live rock is really simple:

  • Don your safety glasses, and gloves
  • Inspect all your pieces of live rock, inspecting for pests, nuisance algae, or dead organisms. Black patches are usually a dead animal
  • Scrub the dead pieces and remove any pest you can find
  • Rinse in clean RO/DI water
  • Place each rock in the container/bin
  • Fill with clean, freshly mixed saltwater at 1.025 SG
  • Insert the powerhead and ensure good water circulation throughout
  • Insert the heater and set to 78-82°F
  • Cover with lids and leave for 1 week
  • Check ammonia and Nitrite readings after 1 week
  • If ammonia >5ppm do a 100% water change
  • Repeat until both your ammonia and nitrate are zero
  • This process can take between 1 week to several months to complete!
  • You can now add the rock to your aquarium

No matter what you have heard or read NEVER boil live rock to cure it! This could lead you to Palytoxin Poisoning which in rare circumstances can be fatal!

I suggest you have a read of my article of Palytoxin Poisoning so you are aware of it:
Palytoxin Poisoning – Click Here

How Do You Select Good Live Rock?

There are several things you can do to avoid having to cure your own rock and select the highest quality live rock to ensure your aquarium remains as pest free as possible:

  • Thoroughly inspect the holding facility you are purchasing your live rock from. If you can see pests and nuisance algae in the tanks – Walk Away!
  • If you are buying the live rock from an online supplier seek out reviews from previous customers via a google search
  • Look at prices per pound and shipping costs – driving to inspect and pick up your own rock may be a safer alternative.
  • If purchasing from a fellow reefer try and inspect the tank before it is sold to you – Again, any pests or nuisance algae – Walk Away.
  • If you are ever unsure about the rock, cure it and quarantine it before actually starting your tank – Running the rock in a bare tank for two months to see and remove any hitchhikers is far easier than tearing down a beautiful reef in 3 years to catch a Bobbit worm!
    • Click Here for a scary forum story on a Bobbit Worm!
Aiptasia Aquarium Pest Coral
Aiptasia Aquarium Pest Coral

To Finish

Live rock is the backbone of your aquarium’s biological filtration and no matter if you are planning a Fish-Only aquarium or a full-blown reef tank your aquascape should be using this rock!

With careful selection and a small amount of due diligence, you can soon have a stunning piece of the world’s coral reef in your home or office with minimal problems!

For those who wish to really begin their aquariums journey in a sterile manner then Dry Rock is an option. This is how I began mine, it just takes longer to cycle and mature!

Richards Reef Dry Rock
My Reef With Dry Rock – Day 1

Further Reading

To help you in your learning journey you may find the following articles helpful:


Hi, I'm Richard and I have been an avid aquarist for over 30 years with a passion for Saltwater Aquariums. I love to pass on my knowledge to help others get the same amount a pleasure out of this hobby as I do. View my About Me page to find out more about me & my mixed reef aquarium.

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