Live Rock For Saltwater Aquarium: Choice, Setup, Use, Pros

“Live Rock” is a special type of decoration and at the same time an important element of the saltwater aquarium’s life support system. They are collected from coral reefs and delivered to us in a wet state so that algae, animals, and microorganisms are preserved on their surface and inside numerous pores and holes. Live Rock For Saltwater Aquariums can bring your home aquarium as close as possible to a real coral reef ecosystem.

live rock for saltwater aquarium

do you need live rock in a saltwater tank?

The more “live stones” in the aquarium, the better!. Yes live rock are needed in saltwater tank. Increasing the amount of live rock used as aquarium decorations and biofilter fillers at the start of the aquarium results in the following benefits for saltwater tank:

  • a sharp acceleration and facilitation of the launch of the aquarium biological water treatment system ;
  • a significant reduction in mortality, improved coloration, increased immunity of animals, incl. – reducing the likelihood of diseases and reducing the severity of these diseases, if they occur;
  • increase the stability of the hydrochemical regime of the aquarium;
  • improving the decoration of the aquarium.

It is especially important to use live stones in aquariums inhabited by those species of fish and invertebrates that make the highest demands on the conditions of detention. First of all – in reef aquariums with live corals.

It is unlikely that in the foreseeable future it will be possible to obtain any full-fledged artificial analogue of living stones.

What does live rock do for a saltwater tank?

Porous structure and huge inner surface developed relief (many potential shelters), physical structure and chemical composition of the material (calcium carbonate with an admixture of other useful elements), high decorative qualities, animal and plant populations unique in composition and diversity (micro-, meio- and macrobenthos) of the surface of living stones and their internal pores and cavities, adapted to living on / in such a substrate – these are the main advantages of this material.

This is in short, but we will continue.

The inhabitants of the pores and cavities of a living stone (taking care of their nutrition, respiration and release from metabolic products) actively pump water through its “body”. The result is a very efficient biochemical reactor with a bunch of useful additional options.

Organisms that enter the aquarium along with living stones settle on the ground, decorations, hidden cavities, biological filter fillers and other substrates, dramatically increasing biodiversity and, accordingly, the stability of the aquarium ecosystem.

Unlike a classic biofilter, the useful activity of living stones is not limited to the oxidation of highly toxic nitrogen-containing excretions of fish and other aquarium animals to relatively harmless nitrates. On the surface and in the thickness of living stones, there is a really complex processing of most biogenic compounds polluting water (including nitrates, phosphates and organic acids) to simple and biologically neutral substances.

In addition, live rock can be involved in maintaining the buffering capacity of aquarium water and maintaining its pH stability. In the depths of the pores, as well as under algal growths, the dissolution of the material from which they are composed can occur. That is, living stones, among other things, serve as an additional source of calcium and magnesium ions, bicarbonate ions and trace elements.

With the help of live stones, you can “revive” DSB sand (Deep Sand Bed a thick layer of sand – a system for maintaining water quality in Saltwater aquariums, based on a thick layer of sandy soil).

Many inhabitants of living stones are able to eat pathogens of Saltwater fish. The more live rock in an aquarium, the lower the risk of such diseases. Plants and invertebrates that live and breed on them are a valuable addition to the diet of fish and other animals kept in the aquarium.

At the same time, along with them, you can bring new settlers dangerous for some of your pets into the aquarium. It can be mantis shrimp, carnivorous crabs, fireworms, aiptasia (anemones – glass roses), planaria … Not all Saltwater aquarists consider it desirable to get these animals into a common aquarium. Inspect stones when buying, consult sellers.

Start saltwater aquarium with Live Rock

Living stones play a special role in the launch of a new Saltwater aquarium and in the restoration of its ecosystem, in cases where it is oppressed by the use of drugs, etc.

start saltwater aquarium with live rock

Bacteria and other organisms that provide biological water purification enter the aquarium with stones. Moreover, immediately in an active state, and precisely those species and strains that are able to immediately begin to work and multiply in the water of a tropical Saltwater aquarium (with its characteristic hydrochemical characteristics, temperature and composition of pollutants). The latter circumstance favorably distinguishes living stones from artificial bacterial preparations.

Some of the organisms arriving with living stones die and, decomposing, provide the load necessary for the rapid reproduction of bacteria involved in the biological purification of water. Moreover, it imitates with high accuracy the load on biofilters that occurs during the life of hydrobionts contained in Saltwater aquariums. Therefore, to start the aquarium ecosystem, freshly arrived stones are often used.

It is recommended to place live stones in a new aquarium 3-5 days after it is “salted”. In case of a very big hurry, you can reduce the waiting time to 1-4 hours, but you need to understand that freshly made artificial sea water is quite aggressive and losses among the population of stones will increase.

There are different opinions about the order of laying and choosing live stones. It is difficult to give clear recommendations. A lot depends on the amount of dead organic matter on specific living stones, the design and performance of the life support system of the aquarium, its inhabitants.

It is possible to use both freshly arrived and overexposed living stones in various proportions.

Freshly arrived stones of especially high quality (an abundance of characteristic fouling, dead animals and plants are not observed, there is no putrefactive smell) are used without special restrictions, almost in the same way as overexposed ones. Both those and other stones can be placed in the aquarium in large batches, up to a one-time laying of the entire planned volume of stones at a time.

If there is a lot of dead organic matter on and inside the rocks, their excess can poison the water and seriously disrupt the aquarium ecosystem.

Based on the realities of the domestic market, for novice Saltwater aquarists, for whom it is still difficult to determine the quality of live stones, we recommend that you first place a small amount of overexposed stones in the aquarium. A few days later, after the initial “revival” of the aquarium ecosystem, you can add freshly arrived stones, preferably in several steps and mixed with overexposed ones. Not forgetting to control the concentration of ammonium and nitrite in the aquarium water.

The first fish and other animals are carefully introduced into the new tank about two to three (sometimes four) weeks after the live rock is placed. Having previously made sure that the content of ammonium and nitrites in the aquarium water is steadily decreasing and is either equal to zero or has reached the values ​​acceptable for your pets.

If it is necessary to add live rock to an aquarium already stocked with fish and/or susceptible invertebrates, this should be done carefully, according to the life support system’s capabilities and monitoring the water quality with tests. The addition of well-over-exposed live stones is the least dangerous. If freshly arrived living stones are added, then this is done in small portions.

Choosing live rock for saltwater aquarium


Usually they try to choose live stones with the most developed relief an abundance of protrusions, depressions and cavities. Sometimes they prefer openwork structures, which are based on branched skeletons of long-dead corals.

Such stones provide the mobile inhabitants of the aquarium with a wide variety of shelters. As a rule, it is easy to attach sessile invertebrates to them. They are easy to lay, creating beautiful surfaces and shapes.

Do not forget about the requirements for strength. This is especially important for living stones that form the basis of decoration.

If you intend to keep large pelagic fish – fast and agile – such as blacktip reef sharks ( Carcharhinus melanopterus ) in a multi-ton aquarium, it is better to stay on smooth stones with a minimum of protrusions. This will help reduce the chance of injury and getting these fish stuck.

live rock with algae and other populations

Abundant and diverse living fouling on the surface of living stones is an indicator of their quality. Evolved life on the surface usually corresponds to an equally abundant population of the inner voids.

Freshly arrived stones have the richest and most diverse population. During storage in the store, even if there are good conditions there, some of the inhabitants of living stones leave them or die (including those that could survive with you, since the conditions in your aquarium are different from the aquarium in the store).

On the other hand, by placing unexposed stones in your aquarium, you run the risk – the decay products of their inhabitants who died during transportation can lead to poisoning of the aquarium water.

At the same time, along with them, you can bring new settlers dangerous for some of your pets into the aquarium. It can be mantis shrimp, carnivorous crabs, fireworms, aiptasia (anemones – glass roses), planaria … Not all Saltwater aquarists consider it desirable to get these animals into a common aquarium. Inspect stones when buying, consult sellers.

Algae An

the abundance of live crustaceans (calcareous algae in various shades of red, reminiscent of terrestrial scale lichens) is desirable and is considered one of the indicators of the quality of stones.

“Fleshy” algae, such as caulerpa, do not withstand “dry” transportation. It is better to refrain from acquiring living stones overgrown with them (except when these algae have not already grown in the seller’s aquarium). If you still have to buy, then dead algae must be carefully removed so as not to spoil the water of the aquarium.

Sessile invertebrates

Small living stony corals and other intestinal animals are often found on the surface of good stones. Their composition may vary depending on the region and the specific place of extraction. More often than others, you can find porites, zoanthids and small sea anemones, sometimes clavularians. If you manage to place such a stone in good conditions, then these animals will take root in the aquarium and grow.

Mobile invertebrates

The vast majority of mobile invertebrates that can survive during transportation are very good at hiding (those who were not able to do this were eaten in the ocean, and a long time ago). Even carefully examining the stones, you can find only a few of them. Nevertheless, the longer the time passes from the moment the stones are delivered from the place of extraction of live stones to their placement in your aquarium, the less of them will remain (they die, eat each other, move …). This is especially true for “large” (from 1 cm) crustaceans.

Unwanted inhabitants of living stones

With live ones, you can bring new settlers dangerous to some of your pets into the aquarium. However, the possible damage is far from being as great and probable as it may seem to inexperienced aquarists. In any case, it is incomparably lower than the benefits brought by living stones.

Mantis shrimp

The devil is not as scary as he is painted. Only large specimens can cause serious damage to your pets. And they rarely arrive alive, and it’s easier to notice them when buying. If a large praying mantis nevertheless ended up in an aquarium or grew up on the spot, it can be detected and, if necessary, pulled out along with a stone or caught in a trap.

Carnivorous crabs

Crabs can be a problem. In living stones, they are quite common, and because of the abundance and diversity of species of these crustaceans, it is very difficult to distinguish “pests” from useful small herbivorous crabs. Those who can be found, it is better to immediately put them away and check their food preferences by offering different types of food. If any “villain” still got into the aquarium and he manages to cause significant damage, he will have to be caught (most often with a trap).

Dangerous polychaete worms

Polychaete worms, they are also polychaetes, are a whole class that includes a huge number of species. The vast majority of those who can get into the aquarium and survive in it are of great benefit. Rare exceptions (some fire and carnivorous polychaete worms) usually either do little damage or can be killed without too much trouble.

Aiptasia, planarians, filamentous and blue-green algae …

These animals can only become a problem in a poorly balanced aquarium. In favorable conditions, they are able to quickly increase their numbers and can worsen the condition and even kill some of the animals contained in it.

The main remedy is to normalize the general condition of the aquarium. In addition, you can get those animals that will eat them.

In any case, it is almost impossible to prevent them from entering the home aquarium, for example when buying live corals. Therefore, do not fall into paranoia, discovering the insignificant presence of these unwanted inhabitants of living stones in a commercial aquarium. However, if their number is really large, it is better to think about the appropriateness of the purchase.

Causative agents of diseases in aquarium fish

The risk of transmission of diseases in aquarium fish is relatively low, since the inhabitants of living stones are happy to feed on their pathogens. However, of course, it is best to refrain from purchasing live rock from an aquarium that contains sick fish.

Live rock Region

The region of origin of living stones, in our opinion, is not very important.
The main thing is the specific supplier: it is he who must ensure the quality of live stones and its stability.

how much live rock in saltwater aquarium?

It is generally considered optimal to place enough live rock in the aquarium so that its volume is between one-third and one-half of its volume. However, for financial reasons, this is not always possible – the stones are not cheap.

how much live rock in saltwater aquarium

In addition, the needs of the aquarium population must be taken into account. Active swimmers need a lot of free space. Moray eels are insensitive to water quality, on the other hand, the abundance of shelters can lead to the fact that, apart from the moment of feeding, the owner will almost never see his pets.

The specific gravity of living stones is quite variable. Usually for good quality stones in the wet state, it is approximately 1.6-1.7 kg / l (for some reason, I have not seen such data in the literature – I had to measure it myself, taking a couple of samples from a batch of overexposed Indonesian stones).

However, when we talk about the volume occupied by living stones in an aquarium, we most often do not mean the total volume of all stones, and even more so not the volume of water displaced by porous stones (who can say how much water is enough to drain or evaporate from a stone before the moment he ceases to be considered alive?).

We are talking about the volume of the aquarium, limited by a curved surface, tangent to the outer ledges of the scenery, lined with living stones. And to put it simply – what part of the aquarium (“by eye”) is occupied by the mountain of living stones lying in it.

In this case, very roughly, one kg of live rock occupies one liter of aquarium space.

How many are needed for a particular aquarium is a creative question. However, for aquariums from 100 liters to several tons, we recommend the following ratios:

– for reef aquariums – from 20 to 50 kg of live stones for every 100 liters of volume (or, if the number of stones is expressed as a percentage of the volume of the aquarium – 20-50%);

– for aquariums inhabited by fish and invertebrates resistant to captive conditions – from 10 to 20 kg of live stones for every 100 liters of volume (10-20%).

The larger the volume of the aquarium, and the higher the resistance of the animals contained in it to captive conditions, the smaller the relative (per volume) amount of live rock can be used.

how to add live rock to a saltwater aquarium?

The add and use of live stones as elements of decorative design makes it possible to imitate the surface of natural reefs with high accuracy. In addition, decorative structures made from live rock provide the aquarium inhabitants with plenty of hiding places. This is especially important when aggressive and predatory fish are kept together with small-sized or poorly resistant fish.

Installation of scenery

Easy styling

If the decoration is not too steep and high (especially if the aquarium has been made wider and lower – which in general should be strived for for many reasons), you can stack live rocks on top of each other to your liking, creating a beautiful relief and providing places for immobile invertebrates (the base can be laid out, for example, with limestone). This option is used most often and is attractive because it does not require any additional devices, and if necessary, the decoration is easy to disassemble or remake.

Individual stones are sometimes placed in a gap between decoration and glass. However, this may result in scratches.

On pins

You can attach living stones to each other by drilling holes in them and inserting plastic or titanium pins (usually cut from titanium wire). In this case, a large number of holes are drilled in the stones at once. However, it should be noted that in good reef aquariums, these holes eventually become overgrown with calcareous algae and other “living material”.

On the frame

You can assemble the mounting base from PVC pipes with holes and other bulky plastic elements. Or fix a strong rigid plastic mesh on the back wall. And then attract live stones to this base with plastic self-tightening mounting belts (often used for fastening cables and pipes) or tying with a cambric, sawing live stones if necessary and drilling holes in them. When sawing and drilling live stones, make sure that no metal particles remain in them.

On glue

Of the adhesives, a two-component epoxy adhesive is used. Especially for Saltwater aquariums, it is offered, for example, by the German companies Aqua Medic (“Reef Construct”) and Tunze. The glue is two “sausages” in consistency resembling plasticine. Like plasticine, they are kneaded and at the same time mixed in equal proportions. It, of course, hardens in water, but sticks to wet surfaces rather poorly, and almost does not stick to the surfaces of living stones covered with organic matter. In addition, when trying to glue under water, it is washed out and dusty. However, such glue can slightly bind stones, clinging to bumps.

It is more convenient to assemble decorations from living stones on epoxy glue “dry” – before filling the aquarium with water or beyond. Places of gluing on wet stones are dried with a rag or napkin, after which glue is applied.

In addition, you can assemble the base of the decoration in a dry aquarium by gluing the stones of the dried-up peeled sea limestone with a two-component epoxy glue. Artificial “stones” made of ceramic slag, such as “Grotten Ceramic” and “Grotten Lava” from Hobby, can be fixed with the same epoxy adhesive, but easier and cheaper – aquarium silicone sealant. In this case, it is necessary to specially provide platforms and crevices for the subsequent placement of live stones.

Attaching sessile animals to live rocks

Of course, first of all, it is necessary to take into account the ecology of these animals. Not everyone will agree to live on a rock – some, for example, like sandy soil. Almost all invertebrates have their own preferences regarding water mobility, lighting and nearest neighbors.

The easiest way, when laying out the scenery from live stones, is to provide special platforms and recesses for placing corals and other immobile invertebrates. However, this is not always enough. Not all animals themselves can reliably “grow” to a hard substrate. In any case, it will take time. Until self-fixation occurs, they can be knocked down by stubborn or awkward fish, hermit crabs, gastropods and other aquarium “elephants”. The current of water can also turn them over and throw them off. And the owner himself, putting things in order in the aquarium, may not be careful enough.

Soft Fastener

Soft corals, colonies of zooanthars and some other “soft” coelenterates (but not sea anemones) can be fixed with simple packing rubber bands or plastic mounting belts. Just don’t push them too hard. If it is possible to ensure the immobility of the animals, then subsequently they adhere to the substrate and the fasteners can be removed.

Sometimes this method works for stony corals as well.

Two part epoxy adhesive

This type of glue has already been discussed a little above. Such a mount can apparently be considered the most reliable and convenient for stony corals (especially branched forms) and gorgonians. The consumption of glue in this case is small. Its surface in the aquarium quickly becomes covered with fouling and becomes almost indistinguishable from the surrounding substrate.

Glue based on cyacrin

Of this type of adhesives at the household level, Super Glue Gel and Super Moment are the most accessible today. In addition, various types of such glue are sold in stores selling goods for modeling.

If the stone to which the coral needs to be glued cannot be removed from the water, a drop of glue should be applied to the base of the coral or other spineless creature that has a “hard and dead landing site”, quickly lowered into the water, and firmly and firmly planted in the chosen place. Everything can work out if you manage to save a drop of glue (in water it hardens instantly, but on a drop the hardened layer is able to form a protective film). Judging by the reviews, not everyone succeeds, not always, and not with any glue. Thick glue seems to be preferable. The glue holds the better, the thinner its layer is – it is better to choose even surfaces for gluing.

If the base stone can be removed from the water, the task is simplified. The surfaces to be glued should be slightly wet/dry, apply glue to them, attach, squeeze. The joints are slightly spilled with glue. The finished product is in the water.

Life span of live rock

Unfortunately, over time, living stones can “age” – their filtering ability decreases. This is due to the fact that not all of their inhabitants are capable of reproducing in an aquarium, and the life span of any living organisms is limited. In addition, the surface of living stones is often overgrown with algae and other living organisms, which can lead to blocking of the entrances to internal channels and pores. If the aquarium’s life support system is based primarily on the cleaning power of live rock, this fact should be kept in mind and periodically (once every 1-3 years) new rocks should be added and/or old ones replaced.

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