reeffirstaid
Active Member
It seems like the poster child for a top notch reef aquarium, is always a photo of a tank, filled to the brim with colorful acropora corals. Why acropora, what makes it the determining factor in a gorgeous, thriving reef. Perhaps it's because, for many, keeping acropora corals long term, and in vibrant color, marks a significant milestone. These guys test our skills as coral reef aquarists, and aren't just a canary in coal mine, when it comes to water quality. If something is off, acropora colonies go into a frenzy and are quick to perish. So what makes them so difficult to keep? Is it their zero tolerance of less than perfect water quality, the fact that they demand powerful lighting, or is it something else? We know the fundamentals of a healthy reef aquarium, how do they apply to acropora corals? Understanding the biology behind small polyp stony corals can help, shedding some light into what makes an acropora, well, an acropora.
Biology:
Acropora represents a genus of corals in the phylum Cnidaria, which is home to over 10,000 marine animals. Commonly seen elkhorn, or staghorn coral, are just two members of the 149 described species of acropora. These are reef builders, creating complex calcium carbonite skeletons that build the structure of coral reefs. As many reef aquarists know, acropora colonies come in a variety of different shapes and sizes, some tabling out while others shoot straight up, toward a light source. The polyps on this species are small, typically about 2 mm, sharing tissue and a nerve net. While each polyp is essentially an individual, they share enough that the colony can react together, based on shared nerve signals. During the day polyps protrude slightly, and at night they extend, catching organic matter within the water.
All species of acropora are prone to bleaching, a total loss of symbiotic algae. In many cases, this leads to the demise of the entire colony. Worldwide, on natural coral reefs, sedimentation, ocean warming and eutrophication, have all led to the loss of living acropora.
While acropora are gorgeous, they are also delicate and prone to bleaching.
In the aquarium:
Acropora corals glow within aquarium water. Rich blues, reds, purples, nearly every color in the rainbow is displayed on different species. It's interesting to note, the algae within the coral's tissue is a golden brown. Often, acropora colonies will brown within the aquarium. This is often due to nutrients, such as phosphate or nitrate, present in high quantities. It's important to understand, that the colors we strive for in these colonies, comes not from their symbiotic algae, but from a layer of skin that protects the colony from the harsh rays of the sun. This layer of tissue has evolved, to create rich and dynamic colors, which aid the coral in literally preventing a sunburn. We have to balance water quality, allowing enough zoxanthllae to survive, that the coral gets food, but not so much that the golden brown algae takes over, washing out the color of the coral's protective skin layer. Powerful lighting enhances this skin layer, thus offering richly colored specimens.
I noted that sedimentation has killed wild acropora colonies. This is important to note, as our aquariums are often home to sediment, which can easily be stirred up, clouding water. One trend in acropora heavy aquariums, is bare bottom. The use of a bio-pellet, or zeovit reactor, replaces the need for a refugium or sand-bed, and allows the aquarist to remove any unwanted debris easily. This can help ensure that nothing in your tank gets stirred up, harming your acropora.
Without a sand bed to collect debris, bare bottom tanks offer a clean way to keep acropora.
A precarious balance:
There is no silver bullet to keeping acropora healthy and colorful. The trick is, getting everything in appropriate balance, and keeping it stable. To prevent browning, the aquarium must be void of nitrate and phosphate. Yes, you can have a small, slightly detectable level of either, and still have beautiful acropora in your tank. If it gets out of hand, your acros will let you know, as rich purples and blues, transform into a uniform golden brown.
As I said, stability is key. A tropical reef aquarium should be kept between 76 to 78 degrees. Large variation in temperature, especially temperature rises, wreaks havoc on acropora. It's for this reason that often using a controller, is vital to acropora health. The controller can cut the heater off, in case of it sticking in the on position, and switch fans on if necessary, if the tank gets too hot. This is helpful, since often, the intense lighting required to promote rich colors, generates a lot of heat.
When keeping acros, we often step outside the circle of reef fundamentals. Most aquarists monitor calcium, alkalinity and magnesium. Many don't monitor iron, potassium and iodine, along with a host of others. The following is a breakdown of water parameters I have found acropora thrives under:
Ph: 8.18 night – 8.23 day
Temperature: 76 night / 77 day
Potassium: 380 ppm
Iodine: .06 ppm
Iron: .025 ppm
Alkalinity: 12-14 dKH
Nitrate: undetectable
Phosphate: .002 ppm
Density (Specific Gravity): 1.026
Calcium: 450 ppm
To properly test water when keeping acropora, accuracy is key. A good lab grade test kit work well. Digital lab grade checkers are better.
In the wild, acropora grows in all shapes and sizes, forming the physical backbone of the reef
Do I need a reactor?
I've kept acropora colonies, in pretty dense numbers, and never installed a calcium reactor. That said, to maintain low nutrient levels, I've used sulfur based de-nitrators, along with bio-pellets, but settled for a zeovit reactor, as the biological processes that take place within, allow for coral feeding. These guys are calcium hogs, so if you find dosing isn't keeping your calcium level in check, a reactor isn't a bad idea. Just remember, when starting a calcium reactor, any mistakes can lead to instability, and there is nothing acropora hates more, than instability. To answer the question of needing a reactor, it is very likely to create thriving acropora, you will have a reactor, in some form or another.
Amino acids?
Amino acids are important organic compounds, composed of amine. Amino acids combine, to form proteins. They are building blocks of life, and supplementing your aquarium with them, guarantees that corals have them, readily available. Since in the aquarium, most of the nutrition acropora colonies get, comes in the form of sucrose handed down by symbiotic algae, amino acids help complete the chain of nutrition, so that the animal can utilize calcium to build a strong skeleton and colorful tissue. Most of the amino acid supplements for reef aquariums cover all the essential amino acids, but a few to look out for are:
Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. All of which are gained through consumption of food.
Lighting:
It's hard to over light an acropora. It can be done, but if properly acclimated to a light source, these guys thrive under very bright conditions. For years, metal halides were the weapon of choice, though today, powerful LED lights can create an optimum environment for all species of SPS corals, including acropora. When deciding on lights, if acropora is in your reef keeping plans, the more powerful, the better. It's important to remember, that on natural coral reefs, corals only receive about 6.5 hours of heavy, intense sun. It's not uncommon for us to light a captive reef for 12 hours. If this is the case, make sure your lights, (if LED) are ramping up, remaining intense for about half that time, and ramping back down. If you employ multiple T5 lights along with metal halides, switch bulbs on independently, over the course of a few hours.
Coral pests:
Acropora is one species that comes with its fair share of pests. While many aquarists don't extend quarantine to corals, in the case of this species, it becomes very important. A coral quarantine tank is simple, mainly eggcrate, heating and filtration. Sadly, the water quality needs to be kept on par with your display tank, so cost can be incurred in setting a coral quarantine up. This combined with a good routine of dipping each and every specimen. For best results a quarantine of at least 2 weeks to one month, can ensure that any pests are treated, and don't make their way into your display tank.
Treatment for pests varies. I personally recommend a dip of Sailfert's flatworm exit and Brightwell Aquatic's Coral RX – as an all-purpose dip for all new arrivals. If you can't quarantine, then a long dip in either, or both, of these products is recommended. Aquarists have been experimenting with using Bayer Advanced as a coral dip, though since I have no experience with it, I can't fully comment on success rates, especially long term.
Considering the fact that acropora comes from some of the brightest environments on Earth, the can handle all the light you can toss their way
Understanding the colony mentality:
One thing most certainly true about acropora, anything that happens, happens to the entire colony. Yes, one specific area of the coral may bleach, or a few polyps may die. Anything there is distress, the entire coral colony is in distress. It's for this reason, that stability is so vital, to the survival of these corals. If you're ready to take the plunge, and keep acropora, make sure everything is in check, balanced and stable. Under the right conditions these corals grow quickly and help build the structure of your reef. Patience is a virtue, and don't be surprised if you don't succeed at keeping acroporas, the first time around.
Like the borg, acropora are a colony, with a shared nerve net
Biology:
Acropora represents a genus of corals in the phylum Cnidaria, which is home to over 10,000 marine animals. Commonly seen elkhorn, or staghorn coral, are just two members of the 149 described species of acropora. These are reef builders, creating complex calcium carbonite skeletons that build the structure of coral reefs. As many reef aquarists know, acropora colonies come in a variety of different shapes and sizes, some tabling out while others shoot straight up, toward a light source. The polyps on this species are small, typically about 2 mm, sharing tissue and a nerve net. While each polyp is essentially an individual, they share enough that the colony can react together, based on shared nerve signals. During the day polyps protrude slightly, and at night they extend, catching organic matter within the water.
All species of acropora are prone to bleaching, a total loss of symbiotic algae. In many cases, this leads to the demise of the entire colony. Worldwide, on natural coral reefs, sedimentation, ocean warming and eutrophication, have all led to the loss of living acropora.
While acropora are gorgeous, they are also delicate and prone to bleaching.
In the aquarium:
Acropora corals glow within aquarium water. Rich blues, reds, purples, nearly every color in the rainbow is displayed on different species. It's interesting to note, the algae within the coral's tissue is a golden brown. Often, acropora colonies will brown within the aquarium. This is often due to nutrients, such as phosphate or nitrate, present in high quantities. It's important to understand, that the colors we strive for in these colonies, comes not from their symbiotic algae, but from a layer of skin that protects the colony from the harsh rays of the sun. This layer of tissue has evolved, to create rich and dynamic colors, which aid the coral in literally preventing a sunburn. We have to balance water quality, allowing enough zoxanthllae to survive, that the coral gets food, but not so much that the golden brown algae takes over, washing out the color of the coral's protective skin layer. Powerful lighting enhances this skin layer, thus offering richly colored specimens.
I noted that sedimentation has killed wild acropora colonies. This is important to note, as our aquariums are often home to sediment, which can easily be stirred up, clouding water. One trend in acropora heavy aquariums, is bare bottom. The use of a bio-pellet, or zeovit reactor, replaces the need for a refugium or sand-bed, and allows the aquarist to remove any unwanted debris easily. This can help ensure that nothing in your tank gets stirred up, harming your acropora.
Without a sand bed to collect debris, bare bottom tanks offer a clean way to keep acropora.
A precarious balance:
There is no silver bullet to keeping acropora healthy and colorful. The trick is, getting everything in appropriate balance, and keeping it stable. To prevent browning, the aquarium must be void of nitrate and phosphate. Yes, you can have a small, slightly detectable level of either, and still have beautiful acropora in your tank. If it gets out of hand, your acros will let you know, as rich purples and blues, transform into a uniform golden brown.
As I said, stability is key. A tropical reef aquarium should be kept between 76 to 78 degrees. Large variation in temperature, especially temperature rises, wreaks havoc on acropora. It's for this reason that often using a controller, is vital to acropora health. The controller can cut the heater off, in case of it sticking in the on position, and switch fans on if necessary, if the tank gets too hot. This is helpful, since often, the intense lighting required to promote rich colors, generates a lot of heat.
When keeping acros, we often step outside the circle of reef fundamentals. Most aquarists monitor calcium, alkalinity and magnesium. Many don't monitor iron, potassium and iodine, along with a host of others. The following is a breakdown of water parameters I have found acropora thrives under:
Ph: 8.18 night – 8.23 day
Temperature: 76 night / 77 day
Potassium: 380 ppm
Iodine: .06 ppm
Iron: .025 ppm
Alkalinity: 12-14 dKH
Nitrate: undetectable
Phosphate: .002 ppm
Density (Specific Gravity): 1.026
Calcium: 450 ppm
To properly test water when keeping acropora, accuracy is key. A good lab grade test kit work well. Digital lab grade checkers are better.
In the wild, acropora grows in all shapes and sizes, forming the physical backbone of the reef
Do I need a reactor?
I've kept acropora colonies, in pretty dense numbers, and never installed a calcium reactor. That said, to maintain low nutrient levels, I've used sulfur based de-nitrators, along with bio-pellets, but settled for a zeovit reactor, as the biological processes that take place within, allow for coral feeding. These guys are calcium hogs, so if you find dosing isn't keeping your calcium level in check, a reactor isn't a bad idea. Just remember, when starting a calcium reactor, any mistakes can lead to instability, and there is nothing acropora hates more, than instability. To answer the question of needing a reactor, it is very likely to create thriving acropora, you will have a reactor, in some form or another.
Amino acids?
Amino acids are important organic compounds, composed of amine. Amino acids combine, to form proteins. They are building blocks of life, and supplementing your aquarium with them, guarantees that corals have them, readily available. Since in the aquarium, most of the nutrition acropora colonies get, comes in the form of sucrose handed down by symbiotic algae, amino acids help complete the chain of nutrition, so that the animal can utilize calcium to build a strong skeleton and colorful tissue. Most of the amino acid supplements for reef aquariums cover all the essential amino acids, but a few to look out for are:
Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. All of which are gained through consumption of food.
Lighting:
It's hard to over light an acropora. It can be done, but if properly acclimated to a light source, these guys thrive under very bright conditions. For years, metal halides were the weapon of choice, though today, powerful LED lights can create an optimum environment for all species of SPS corals, including acropora. When deciding on lights, if acropora is in your reef keeping plans, the more powerful, the better. It's important to remember, that on natural coral reefs, corals only receive about 6.5 hours of heavy, intense sun. It's not uncommon for us to light a captive reef for 12 hours. If this is the case, make sure your lights, (if LED) are ramping up, remaining intense for about half that time, and ramping back down. If you employ multiple T5 lights along with metal halides, switch bulbs on independently, over the course of a few hours.
Coral pests:
Acropora is one species that comes with its fair share of pests. While many aquarists don't extend quarantine to corals, in the case of this species, it becomes very important. A coral quarantine tank is simple, mainly eggcrate, heating and filtration. Sadly, the water quality needs to be kept on par with your display tank, so cost can be incurred in setting a coral quarantine up. This combined with a good routine of dipping each and every specimen. For best results a quarantine of at least 2 weeks to one month, can ensure that any pests are treated, and don't make their way into your display tank.
Treatment for pests varies. I personally recommend a dip of Sailfert's flatworm exit and Brightwell Aquatic's Coral RX – as an all-purpose dip for all new arrivals. If you can't quarantine, then a long dip in either, or both, of these products is recommended. Aquarists have been experimenting with using Bayer Advanced as a coral dip, though since I have no experience with it, I can't fully comment on success rates, especially long term.
Considering the fact that acropora comes from some of the brightest environments on Earth, the can handle all the light you can toss their way
Understanding the colony mentality:
One thing most certainly true about acropora, anything that happens, happens to the entire colony. Yes, one specific area of the coral may bleach, or a few polyps may die. Anything there is distress, the entire coral colony is in distress. It's for this reason, that stability is so vital, to the survival of these corals. If you're ready to take the plunge, and keep acropora, make sure everything is in check, balanced and stable. Under the right conditions these corals grow quickly and help build the structure of your reef. Patience is a virtue, and don't be surprised if you don't succeed at keeping acroporas, the first time around.
Like the borg, acropora are a colony, with a shared nerve net
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