Title graphic for Sea and Sky's Saltwater Aquarium Guide

Saltwater Aquarium FAQ

Frequently Asked Questions



As with any hobby, saltwater aquarium keeping can seem a little intimidating for those who are just beginning. Beginners can have a lot of questions about the the aquarium hobby and about sea life in general. This aquarium faq page contains answers to some of the most frequently asked questions encountered in the saltwater and reef aquarium hobbies, ranging from aquarium setup and maintenance to decorating the tank, choosing livestock, and controlling algae and pests. We will be adding more aquarium questions and answers as time goes by. You can click on one of the questions below to jump directly to the answer, or browse at you leisure by scrolling down the list. If you have an aquarium question that is not answered here, please feel free to contact us by e-mail and we will try our best to answer the question.

Aquarium Setup

Cycling the Aquarium

Live Rock and Substrate

Choosing Fish for the Aquarium

Choosing Invertebrates for the Aquarium

Choosing Corals for the Aquarium

 

Setting Up the Aquarium

What is the best type of aquarium to use?

Any size tank can be used for a saltwater aquarium, Smaller tanks require smaller filtration systems, but larger tanks will provide much more stable water and allow for more fish and invertebrates. It is generally recommended not to use anything smaller than 30 gallons. The best advice is to get the largest tank you can afford and have room for. Be sure to purchase a tank that is made for a saltwater aquarium. The tank should be all glass on the sides with no metal parts anywhere. The salt water will cause the metal to corrode and can poison the water. Aquariums are also available in acrylic, but acrylic aquariums are expensive and can be easily scratched.

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What is the best location in a home for a saltwater aquarium?

When considering a location for your saltwater aquarium, you will want to locate it on a stable, flat surface away from doors and windows. It should also be located away from air conditioning vents and radiators. You want to choose a location that has a fairly stable temperature. Sunlight entering through doors and windows can interfere with the aquarium and cause unwanted algae problems. Water is very heavy, so make sure you find a stable location where the aquarium can rest on a level surface.

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What types of aquarium stands are best to use?

Since water is extremely heavy, it is important to use the sturdiest aquarium stand you can afford. Many aquarium manufacturers make very solid wooden cabinets that can easily support the weight of the aquarium while also providing much-needed storage inside. Many aquarium specialty stores sell tank and stand combos where the tank and stand match in color and style. Make sure you purchase a stand that is made to support the weight of the aquarium.

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What is the best filtration system for a saltwater aquarium?

For a saltwater aquarium containing only fish, it is possible to use a variety of filtration systems. The system you choose will depend on the size of the aquarium and the amount of fish you wish to keep. The best filters are canister filters and sump filters. Canister filters consist of a small canister that fits below the aquarium. The canister contains a pump that pumps the water down into the canister and back up into the aquarium. Canister filters use both mechanical and biological filtration. The main disadvantage of canister filters is that they have to be cleaned frequently and they can be difficult to clean. They are also not a good choice for large aquariums. Sump filters are generally considered to be the best filters available for saltwater aquariums. They consist of a large container that fits underneath the aquarium. There are several different types of sump filters available, and most use some combination of mechanical and biological filtration. Sump filters are a good choice for mid-sized and large aquariums.

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What is the best filtration system for a coral reef aquarium?

The best choice for filtration in a coral reef tank is the Berlin method which uses live rock, or the Jaubert method which uses live sand. Many reef aquarium hobbyists will use a combination of both. The live rock and live sand provide a medium for the nitrifying bacteria to grow. Both methods are used with a sump placed underneath the aquarium and a protein skimmer. The sump provides extra water to the system and provides a convenient are to perform maintenance such as adding supplements and adding water. The sump also provides a location for the protein skimmer, which will help to filter organic waste from the water. This type of filtration can be used for all sizes of reef aquariums and can even handle very large tanks.

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What is the recommended salinity for a saltwater aquarium?

We typically measure the salinity of saltwater by measure the specific gravity. The specific gravity of natural seawater is around 1.025. For a fish-only saltwater aquarium, try to keep the water at between 1.024 and 1.026. Some aquarium hobbyists like to keep the salinity of their fish tanks low because this will inhibit the growth of parasites that can cause diseases. It is possible to keep the water as low as 1.019. This is not generally recommended because it can be stressful and uncomfortable for the fish.

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What is the recommended salinity for a coral reef aquarium?

In the marine aquarium hobby, we generally measure the salinity of saltwater by measuring the specific gravity. For a coral reef tank, it is recommended that you keep the SG of the water at between 1.025 and 1.028. The specific gravity of natural seawater is around 1.025, so this should be your goal for providing a natural environment for your fish and corals.

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How do I measure the salinity of the water?

The salinity of saltwater can be measured using one of three instruments. The least expensive option is to use a hydrometer. A hydrometer is usually a clear plastic container with a floating indicator inside. When you add water, the floating indicator will show the specific gravity on a scale. You can also measure the salinity using a salinity monitor or a salinity refractometer. These are electronic devices that cost more than a hydrometer, but can give more accurate results.

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How much light do I need for a saltwater aquarium?

Lighting a saltwater aquarium with fish and no plants coral can be accomplished using fairly inexpensive fluorescent lights. The general rule is to use 1 to 2 watts per gallon. With fish-only aquariums, the color and spectrum of the light is not as important as it is for reef aquariums. You can select the type of light that best suits your preference and shows off the colors of the fish. You should, however, use lights that are made for aquariums. Do not use standard fluorescent bulbs from the hardware store because they can promote the growth of unwanted algae in the tank.

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How much light do I need for a coral reef aquarium?

Coral reef aquariums require a lot of light. This is because the coral contains a symbiotic algae called zooxanthellae that uses light to make food for the coral. Coral grows in shallow tropic waters and is exposed to a lot of sunlight. Your goal is to attempt to recreate the sunlight in the aquarium. The best light to use for a coral reef aquarium will be either a metal halide/fluorescent mix or one of the new high intensity LED setups. The general rule is to use 4 to 8 watts per gallon. You will also want to make sure you do not choose an aquarium that is too deep because the light intensity drops off sharply with the depth of the water. It is recommended that coral reef aquariums be no deeper than 24 inches.

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How long should the lights be left on?

Lighting a saltwater aquarium depends on the type of aquarium you have. If you have a fish-only aquarium, it is recommended to leave the lights on for about 8 to 10 hours a day to simulate the natural cycle of daylight. Any other time period may stress the fish and could lead to unwanted diseases. Use a timer to provide a consistent lighting cycle for your aquarium. If you have coral in your aquarium, you should leave the lights on for at least 10 hours each day. Coral contains a symbiotic algae that needs plenty of light to survive. Many people choose to divide their lights and use two separate timers. This way they can light one set and then the other to simulate sunrise and sunset. This is much less stressful for the animals in the aquarium than having the lights come on and go out all at once.

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Cycling the Aquarium

What is the nitrogen cycle?

In nature, the nitrogen cycle is a process by which nitrogen is converted through various chemical forms. In an aquarium, the nitrogen cycle begins with ammonia which is given off by fish and other animals through waste and the respiration process. The toxic ammonia is converted to nitrite by special nitrifying bacteria. A second type of nitrifying bacteria converts the toxic nitrite into nitrate. Nitrate is much less harmful to fish than ammonia and nitrite, and is usually removed from the aquarium by making regular water changes.

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How do I cycle my aquarium?

When setting up a new saltwater aquarium, the nitrogen cycle must be fully established before fish or other animals can be added to the tank. This process is known as cycling the aquarium. Once the tank is set up and the filtration system has started, ammonia can be added to the water by adding fish food or raw fish occasionally to the water. You will need to monitor the ammonia, nitrite, and nitrate levels weekly. It usually takes 2-8 weeks to fully cycle a new aquarium. DO NOT rush this process. It is better to err on the side of caution and wait a little longer. Rushing the process will only result in dead fish. The tank is fully cycled when ammonia and nitrite levels drop to zero.

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Is there any way to speed up the cycling process?

There are a few ways to speed up the cycling process. Nitrifying bacteria can be purchased at aquarium stores and added to the water to kick start the process. This can speed up the process considerable to as little as 2 weeks. Another way to speed the process is to use live sand and/or love rock. Live rock and live sand already contain established colonies of nitrifying bacteria and can significantly reduce the cycling time.

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How soon after cycling can I add fish to the aquarium?

Once the aquarium has cycled, it is important to add livestock to the tank slowly and gradually. Start with only one or two fish and wait a few weeks. Test the water regularly and watch the ammonia and nitrite levels. They will go up temporarily as the filtration system adjusts to the new bio load. Once the ammonia and nitrite levels return to zero, you can add one or two more fish to the tank. Continue to test the water regularly and if you notice a spike in ammonia levels, wait several weeks before adding any more animals.

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Live Rock & Substrate

What is live rock?

Live rock consists of small pieces of rock that come from the ocean floor. It is called “live” rock because it is covered with living organisms. It also contains living bacteria that is essential for filtering the water in an aquarium. Good quality live rock can contain beneficial algae, crustaceans, starfish, sponges, and other organisms and can make for a much more natural setting in a saltwater aquarium. Live rock is sold by the pound at most local aquarium dealers.

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How does live rock benefit a saltwater aquarium?

Live rock can benefit a saltwater aquarium in two ways. First, it provides a much more natural look for the aquarium. The rock can be stacked to replicate the look of a natural coral reef. Secondly, it contains nitrifying bacteria that actually helps to filter the water by means of the nitrogen cycle. Live rock is so good at filtering the water that it is possible to set up an aquarium with no filtration system, using nothing but live rock and a pump to circulate the water.

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What is the best type of live rock to buy?

By far the best type of live rock is what is known as pre-cured. When live rock is brought up from the ocean and placed into an aquarium, some of the organisms on the rock will die off. This can raise ammonia levels and foul the water in an aquarium. It takes several weeks for the rock to stabilize in a process known as curing. Once the rock has cured, it is safe to place directly into your aquarium. Cured live rock tends to cost more than uncured rock, so if you are on a budget you may want to purchase uncured rock and cure it yourself.

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How do I cure live rock for use in the aquarium?

Uncured live rock must be cured before it is safe to place into an aquarium. Some of the organisms on the rock will die off after being removed from the ocean, and this die-off can foul the water in an aquarium. To cure the rock yourself, you will want to place it into a large plastic or glass container filled with premixed salt water. Use a pump to provide good water circulation and wait several weeks. There will be a strong smell at first that will go away once the rock cures. Test the water regularly. When ammonia and nitrite levels read zero and there is no bad smell, the rock is safe to add to your aquarium.

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How should I select the right pieces of live rock for my aquarium?

Since live rock is typically sold by the pound, you will want to select pieces that are less dense. Look for pieces with a lot of holes. This makes the rock lighter and provides hiding places for fish and invertebrates. It also provides more surface area for beneficial bacteria to grow. Think about how you want to stack the rock in your aquarium and select pieces that will stack easily. Be sure to select a few large, flat pieces to make shelves and build caves for fish to hide and swim through.

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How much live rock will I need for my aquarium?

If you are going to be using live rock are you primary filtration system in your aquarium, it is recommended that you use about one and a half pounds of live rock for each gallon of water in the aquarium.

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What is substrate?

Substrate is simply the material that is placed on the bottom of the aquarium. Substrate serves two purposes. It provides a natural looking setting for the aquarium and it also can help to filter the water.

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What is the best type of substrate to use in a saltwater aquarium?

The best type of substrate for a marine aquarium is one that is high in calcium. Crushed coral and fine sand known as aragonite are both good choices. Crushed coral is much more coarse and will give the system a different look. It really comes down to personal choice. Many reef aquarium hobbyists prefer live sand. Live sand is cultured in the ocean and contains naturally-occurring bacteria and other critters that help to filter the water and keep it clean.

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What is live sand?

Live sand is sand that has been cultured and removed from the ocean. It contains many tiny animals and microorganisms that can be beneficial to a marine aquarium. Live sand can be used to filter the aquarium water along with a protein skimmer to remove organic waste. This type of filtration is known as the Jaubert system.

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How does live sand benefit a saltwater aquarium?

Live sand is beneficial to an aquarium because it contains animals and microorganisms that help to filter the water. These bacteria help to break down waste materials and keep the water clean. Live sand can be obtained from most local aquarium retailers.

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What is the pink/purple stuff that covers the live rock?

The pink, purple, and red colors you see on the live rock are caused by a special type of algae called coralline algae. This algae actually contains a calcareous skeleton. It is highly desirable in a reef aquarium and can be an indicator of good water quality when it grows and spreads within the aquarium.

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Why is my live rock turning white?

Coralline algae turns white when it dies off. This is a sign that something is seriously wrong inside the aquarium. Low calcium levels and improper alkalinity levels are usually the cause. Some toxins in the water can also cause coralline algae to turn white. If you see this problem in your reef aquarium, you should get your water tested as soon as possible to identify the cause. Work with you local aquarium store to find a solution.

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Choosing Fish for the Aquarium

Can freshwater fish live in a saltwater aquarium?

Most freshwater fish will not survive in salt water. This is because of a process known as osmosis. Osmosis causes water to move from low concentrations of salt to high concentrations. If a freshwater fish is exposed to saltwater, its cells will lose water and the fish will die of dehydration. There are some exceptions. Salmon, eels and some trout have adapted the ability to survive in both salt water and fresh water. There are also a few species of fish that live in what is known as brackish water, which is slightly saltier than fresh water but not quite as salty as salt water. These species can adapt over time to live in salt water. An example of these is the molly.

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How many fish can I put in my saltwater aquarium?

The number of fish you can have in an aquarium depends on the size of the aquarium and the type of filtration. The general rule is no more than one inch of fish for every five gallons of water. You may be able to keep more than that if you have a really good filtration system and maintain the system with regular water changes.

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How long do saltwater fish live?

With proper care and a good environment, most species of saltwater reef fish can live for ten years or more. There have been reports of clownfish living up to 28 years in a reef aquarium. There may be some exceptions, but if your fish are well taken care of, they should reward you with many years of enjoyment. It will depend on how old the fish was when you purchased it, but many species are aquacultured these days and should be fairly young. I personally have a yellow tail blue damselfish that I have had for ten years and a yellow tang that has been in my aquarium or six years.

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Do fish sleep when the lights are off?

Believe it or not, fish actually do sleep at night. If you shine a light in the aquarium at night, you will notice the fish will be moving very slowly and their colors may also be less pronounced. They will act dazed as swim as if they are confused. This is why it is important to put your aquarium lights on a timer to ensure a consistent lighting schedule that simulated the normal day and night cycle.

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Does buying saltwater fish harm the environment?

All though some fish are captured in the wild for the aquarium trade, many species are now bred and raised in captivity. Many corals are now propagated from cuttings known by hobbyists as frags (short for fragments). Live rock is now being aquacultured specifically for the aquarium business. If you are concerned about the environment, talk to you local fish stores and find one that purchases animals that are bred and grown in captivity.

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What is aquaculture?

Aquaculture is the farming of aquatic organisms such as fish, crustaceans, and molluscs. In the saltwater aquarium hobby, aquaculture is the process of breeding fish and invertebrates in captivity. Aquaculture reduces the impact of the aquarium hobby on the environment. Several species of fish including clownfish are now bred and raised in captivity. Corals are now being grown from fragments that are cut. Live rock is now being grown in the ocean for the aquarium trade. Farmers take limestone rock and submerge it in the ocean for several years, allowing organisms to colonize the rock.

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What types of fish are easy to keep in a saltwater aquarium?

The easiest fish to keep for beginners are clownfish, damselfish, blennies, gobies, and wrasses. These species are usually easy to acclimate and are a bit more tolerant of water quality issues than many other species.

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What types of fish should I avoid?

Angelfish and tangs are a bit more sensitive to water quality and may require a bit more experience. Butterflyfish are one of the most difficult types of fish to keep in an aquarium and should only be kept by more experienced hobbyists. Lionfish can be difficult to keep because they must be fed live food. Seahorses are extremely sensitive and difficult to keep. They require live food and do not do well when kept with other types of fish.

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When buying a fish, how do I select a healthy specimen?

When selecting animals at the aquarium store, examine them closely to make sure they look healthy. Make sure they do not have any marks or white spots on them. Make sure their eyes are clear and not white. Ask someone at the store to offer them some food so you can make sure they will eat. Do not purchase an animal that refuses to eat at the store. When purchasing coral, select a specimen with fully open polyps. Do not purchase any coral with dead spots on it. Most aquarium stores will offer a guarantee of one or more days in case the animal dies when you get it home.

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How should I acclimate the fish before adding it to the aquarium?

The best way to acclimate new animals is to put them into a clean bucket along with the water that came with them. Gradually add water from the aquarium to the bucket using a measuring cup or by using some plastic tubing. Start a siphon in the tube and tie a knot in it so that the water drips slowly into the bucket. You will want to gradually add about three times the amount of water from the aquarium that was originally in the bucket over a period of 15 to 30 minutes.After that you can add the animals to the tank using a net. Be careful not to get fish fins and gills caught in the net. If you have invertebrates in your aquarium, DO NOT put any of the water that came from the aquarium store in your tank. Many aquarium stores put copper in their water to help prevent dieases in the fish. Copper is extremely toxic to invertebrates and will kill shrimps, crabs, and coral.

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Can I put sharks in my aquarium?

All though sharks can be kept in aquariums, they are one of the most difficult types of fish to care for. They require large amounts of live food and need a lot of space to swim. They require a very large aquarium and will eventually become too large to keep in captivity.

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Choosing Invertebrates for the Aquarium

What types of invertebrates are easy to keep in a saltwater aquarium?

Invertebrates are more difficult to keep than fish. They are much more sensitive to changes in water quality. If you decide to keep invertebrates, you will have to closely monitor your calcium and alkalinity levels. You will also have to use extremely pure water. Tap water is not an option with invertebrates. For the beginner, hermit crabs, snails, and soft corals are probably the easiest to keep. They are generally more tolerant of water problems.

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What precautions need to be taken when keeping invertebrates in an aquarium?

Invertebrates are sensitive to changes in water quality. They also require calcium and alkalinity levels to be maintained at proper levels. If you plan to keep invertebrates, you will need to routinely test your calcium and alkalinity levels. You will also have to use very pure water. It is recommended to invest in a RO/DI water filtration system. Do not use tap water under any circumstances. Tap water contains many chemicals that are toxic to invertebrates. These chemicals will build up over time as you do your water changes. If you are unable to get an RO/DU filter, you can use distilled water from the grocery store. Many aquarium stores also sell premixed saltwater for use in reef aquariums.

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Can I keep an anemone for my clownfish?

Anemones are notoriously difficult to keep alive in an aquarium. They require flawless water and lighting conditions. They also require a minimum amount of water flow. Even with perfect water and light, some anemones just do not do well in captivity. If you want something for your clownfish to nest in, you may want to consider a soft coral instead. If your water quality is really good, you can try a torch coral. When fully open, torch corals resemble anemones and clownfish will use the coral as a host. Torch corals will close up at night, but the clownfish will adapt to this behavior.

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What invertebrates should I avoid?

Keeping crabs and shrimps will require you to maintain excellent water quality. Cleaner shrimp and banded coral shrimp are usually pretty hardy as long as calcium and alkalinity are kept at optimal levels. Starfish will also require good quality water. Be careful with serpent stars and brittle stars. They can grow quite large in an aquarium. Some can even become fish eaters when they get large enough. Harlequin shrimp should only be kept if you have the patience to care for them. They only eat starfish and nothing else. Hard corals will require flawless water quality and proper lighting levels. They should only be kept by experienced hobbyists. Anemones, clams, and oysters are also extremely hard to keep alive in an aquarium. They should be avoided by all but the most experienced aquarium hobbyists.

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Can I have an octopus in my aquarium?

Octopuses can be kept in an aquarium but are extremely difficult to care for. They should not be kept with fish because they will eat anything they catch. They are incredibly talented escape artists and will climb out of the aquarium through the smallest of spaces. In addition, they are expensive to obtain and have very short life spans. Most octopus species only live for one to two years.

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I thought my shrimp/crab was dead, but I just saw it again. What happened?

No, your shrimp or crab did not come back to life, it just molted. As hard-shelled invertebrates such as crabs and shrimp grow, their hard exterior shell does not grow. They must periodically disgard the old shell by shedding it. THis process is known as molting. When a shrimp or grab molts, they will hide for a few days as the new shell hardens. The old shell is left bedind and may look like a dead animal.

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Choosing Corals for the Aquarium

Are corals difficult to keep in an aquarium?

Corals are among the most difficult animals to keep in an aquarium. They require extremely good water quality and water chemistry. They also require a proper amount of light and water flow. There are many different types of corals. Soft corals are the easiest to keep. They are more forgiving of water quality issues and do not need as much light as hard corals. Soft corals make a good choice for the beginner. Hard corals come in two types. Large Polyp Stony (LPS) corals are a bit easier to keep while Short Polyp Stone (SPS) corals can be extremely difficult to keep alive in an aquarium. SPS corals require bright lights, perfect water quality, and adequate water movement. SPS corals should only be kept by experienced reef aquarium hobbyists.

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What types of corals are available for a coral reef aquarium?

Both soft and hard corals can be kept in an aquarium as long as the water is checked and changed regularly. Soft corals are available in small polyp colonies such as leather corals and gorgonians and large polyp colonies such as button corals and mushroom corals. Hard corals are available in two types. Large Polyp Stony (LPS) corals have large polyps and are the easiest hard corals to keep in an aquarium. LPS corals include torch corals and brain corals. Short Polyp Stony (SPS) corals have short polyps and are much more difficult to keep. SPS corals include acropora, cup corals, and branched corals.

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Does buying coral harm the environment?

All though some coral is still harvested from the ocean, many corals are propagated by cutting fragments to grow new specimens. If you are concerned about the environment, purchase your corals from an aquarium store that gets their corals from cuttings, also known in the hobby as frags.

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What is “fragging”?

Fragging is a process of reproducing corals by cutting pieces, known as frags, to grow new specimens. All though coral is an animal, it can be grown from cuttings just like some plants. Many corals are now propagated by fragging for sale in aquarium stores. Additionally, many aquarium hobbyists frag their own corals to trade with others. Fragging is a method of aquaculture. It is an environmentally friendly method of obtaining coral for reef aquariums.

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