reeffirstaid
Active Member
Ultra Low Nutrient Systems (ULNS)
A few years ago, the term ULNS, started popping up on aquarium forums, and in articles within some of our favorite magazines. The ULNS was described as an ultra-low nutrient system. It suddenly became a trend, and many aquarists were installing bio-pellet reactors, and zeolite reactors, in order to achieve what appeared to be a nutrient free reef. A few years have gone by, and the ULNS fad has had an effect on the hobby. Though, the term itself, ultra-low nutrient system, is very misleading. Do you need to have a ULNS, to be a successful reef aquarist? What’s the red tape, to converting your beloved reef, into a ULNS? Is this really the best way to learn and grasp the fundamentals of reef keeping?
Natural coral reefs:
Natural coral reefs are often described, in scientific literature, as nutrient deprived. This means, when a scientist tests reef water, they find no nitrates, no phosphates, or any other nutrient that would fuel the growth of algae, or impede the growth and development of corals. It’s this reason that corals remain, the greatest builders in the animal kingdom, constructing reef systems that can be seen from space. We see algae on natural coral reefs, even large patches of cyanobacteria, and there is argument amongst scientists, whether or not those are natural occurrences, or the result of climate change.
At any rate, reef water is clean and corals have adapted to this environment. Corals are tough, but they are susceptible to any dramatic change in water quality, or parameters. To understand what makes a ULNS attractive to a reef keeper, we need to understand how corals work. Both LPS and SPS corals use calcium, and other aquatic elements, to construct intricate skeletons. Both corals are communal, in the fact that a group of individual animals, work together, benefiting the whole. In reality, coral polyps are in symbiosis with one another. We know that coral tissue holds zoxanthellae algae. Scientists have now proven that corals, depending on species, get this algae from a parent colony at birth, or they collect the algae in their tissues as they grow.
Zoxanthellae is good, in that it offers corals sucrose as a byproduct of photosynthesis, and the sucrose helps corals quickly build strong skeletons. Zoxanthellae is bad, in that, it really is a foreign biological matter, within coral tissue. Under control and management, the relationship between zoxanthellae and a coral colony functions perfect. The algae is protected within the coral tissue, and the coral gets an extra boost of metabolism from excess sucrose.
When nitrate, or phosphate, are present in water, in any concentration, this fuels the growth of zooanthellae algae. First to discolor, are the coral’s protective layers of skin, which provide the bright and fluorescent colors we strive for. As the zooanthellae overtake the coral, it turns a uniform brown. Left unchecked, corals will actually expel the algae, bleach and likely perish. For this reason alone, nitrate and phosphate must be kept under strict control, without mentioning that phosphate impedes the calcification of coral skeleton.
The ULNS provides this nutrient free water, and allows corals to not only grow, but exhibit strong coloration. For the first time, we are seeing corals in the aquarium, which are far more colorful than their natural counterparts, largely thanks to ULNS.
Achieving a ULNS system
I want to be clear that natural reefs, nor reef aquariums, are ultra-low in nutrients. In fact, much ocean water is purified once in reaches the reef, and the reef lagoon, which is backed up by acres of mangrove forest. Like a refugium, these mangroves assimilate nutrients and provide habitat for young fish, invertebrates, etc. Coral reefs are very efficient at assimilating nutrients, and we need our reef aquariums to be just as efficient. A coral reef is one of nature’s perfect creations. Mangrove forests work in conjunction with microscopic algae to export nutrients, providing corals an environment to grow, which creates habitat for 80% of all oceanic life.
We often export nutrients, in the same way a mangrove forest does. By allowing macro-algae or marine plants, to uptake them during photosynthesis. This worked, but had some downsides. First, successful refugiums were filled with sand, miracle mud, live rock and marine plants. They are messy, and at times, some of that stray debris can enter the display tank. Debris such as sand, or mud, is harmful to sensitive SPS corals’ tissue, and mass tissue loss leads to the coral’s demise. Also, you could overstock an aquarium to a point, where a refugium could no longer keep up with nutrient export. Once that happens, you are back to square one.
We needed a place where both aerobic and anaerobic bacteria could flourish, offered natural habitat for marine animals, and encouraged the growth of tiny marine organisms. Our display tank does most of the work, offering natural habitat with live rock, and a place for tiny marine organisms, such as copepods to grow. They also are rich in oxygen, allowing aerobic de-nitrifying bacteria to flourish. Refugiums were picking up the slack, housing anaerobic bacteria and nutrient exporters, but had their limits.
When bio-plastics hit the scene years ago, like many, I was skeptical. There was nothing natural about a polymer that could be digested by bacteria. Suddenly tanks stocked to the hilt with fish, were turning up, with incredible coral population as well. Bio-plastics were beginning to bridge the gap, taking the place of the refugium, and allowing anaerobic bacteria to flourish, tossing away the need for a messy sand and mud.
Bio-plastics, or bio-pellets, were an important first step, in achieving the ULNS. Though, they had several downsides. The excess bacteria they produced could fuel cyanobacteria outbreaks, if the outflow wasn’t directed into a protein skimmer. While bio-pellets were great at exporting phosphate and nitrate, that is basically where their usefulness ended.
Zeolites are multi-porous elements found in nature. Industry uses them as absorbents and catalysts for various applications, and even produces synthetic zeolites on a massive scale. Given that they are the perfect home for anaerobic bacteria, and can naturally improve water quality, it makes perfect sense they made their way into the marine aquarium hobby.
In our aquariums, on one hand, zeolites function similar to bio-pellets. They give anaerobic bacteria a place to flourish. Though, unlike biopellets, zeolites cannot be consumed by anaerobic bacteria, so therefore they require a carbon source. In addition to giving anaerobic bacteria a home, zeolites naturally absorb certain nutrients from the water, while enhancing the effect of various additives.
The ULNS red tape.
If it sounds too good to be true, than it probably is, or isn’t, or might be. Zeolites do work, producing an efficient way to export nutrients, and heightening certain additives. The catch is, they require strict dosing. They aren’t a carbon source, so therefore they need to be supplemented with one. Partially they act as absorbents, so they require replacing, except if you replace all of them at once, you lose your super anaerobic filter. They work in conjunction with a powerful protein skimmer, which is essentially a requirement on a zeolite tank. Also, they require carbon to polish the water and reach that air standard of water clarity. Another thing, they aren’t cheap. The reactors, media and additives all add up quickly, and you can sink (no pun intended) a fair chunk of dough, getting a zeolite system up and running. Most of all, if not properly set-up and maintained, zeolites can harm, even kill your corals, causing sudden drops in nutrients and trace elements, along with fluctuating water stability.
Like a TV pharmaceutical infomercial, there is plenty of fine print. You can have a dream system, with air clear water and corals that seem to shine within the tank. Though, it’s going to take some elbow grease, and risk, to do so. Once, and if, you are successful, you have an efficient nutrient export system, that actually creates food for your corals. Did I forget to mention that, zeolites need shaken several times daily, to remove any organic sludge from the media. While it is a pain to remember to shake your filter media, the sludge provides a natural food source for corals.
Another paragraph of fine print about zeolite, it is so efficient in exporting nutrients, that often LPS corals, and even some SPS, require supplementation to thrive. Luckily there are a host of products, which not only replace any trace element exported or absorbed by a zeolite reactor, but enhance coral growth and coloration, even for LPS species.
So if I want ULNS, I need zeolites?
Wrong, ULNS has been around for years. While not always achieved with bio-pellets or zeolites, reef keepers have been exporting and absorbing nutrients in all sorts of ways. Algae scrubbers, refugiums, sulfur based de-nitrators, GFO, and many others have worked, and still work, to remove unwanted nutrients from our reef tanks. All of them carry their own set of pros and cons, and refugiums get a partially bad rap because they are so messy. In reality, a ULNS is simply an aquarium with undetectable amounts of nitrate, phosphate, and carefully monitored and supplemented for iron, potassium and other trace elements. How you achieve ULNS is really up to you.
What zeolite does, is allow you to keep a large fish population, feed plenty, and still have the ultra-nutrient free water, we find on the reef. For me, it allows aquarists to create more realistic home oceans. Coral reefs are densely packed, with lots of species diversity. In the reef aquarium, we may have a huge tank, capable of housing a lot of beautiful fish species, but were limited in the confines of what our nutrient exporter could handle. Zeolite, in some ways, has broken down that barrier, by exporting nutrients so efficiently, that additional bio-load is pulled out with everything else. It’s also not nearly as messy to add to an existing aquarium, as a large refugium or algae scrubber.
Is ULNS using zeolite right for me?
Setting out to implement a ULNS, using bio-pellets or zeolite reactors, isn’t for everyone, and especially not for beginners. You won’t really understand how the biological water cycle of an aquarium works, by adding a zeolite reactor. Yes, your new aquarium will cycle faster, and likely remain cleaner if you do so, but it’s important to have the underlying foundation, if you want to achieve long term success.
Also, zeolite requires a keen eye. You need to know how corals appear when they are healthy, and in good coloration. Since much of zeolite usage relies on the aquarist, making adjustments to cope with the appearance of the animals, a beginner might not know what to look for, adding too much of one thing, or not enough of another.
Zeolites are best used in the hands of dedicated and seasoned aquarists. They require a lot of work, and the dosing levels are constantly fluctuating, as you notice changes within your animals. There is no, “set it and forget it” to zeolite usage. You have to remain on top of your reactor’s performance, and from week to week, your dosing schedule will change, especially in the beginning. Also large, frequent partial water changes are a must, to replace trace elements that may be absorbed by the zeolites.
I’m new, what works for me?
For new, even intermediate level aquarists, I still recommend the lightly stocking, all natural approach to aquarium filtration. Using this, you will learn much needed restraint, patience, and aquarium principles, which no reactor or magic dust can teach you. While zeolite reactors can rush you through the ammonia cycle, and plant your feet toward clean water, the principles learned by traditionally cycling, stocking and caring for a reef tank, or more valuable than any filtration media.
If you’re an expert aquarist, with the time, money and drive to try something, albeit risky, then by all means, a zeolite ULNS might be the perfect natural progression for your reef. As home reef keeping progresses rapidly, (automatic dosing, computer control, LED lighting, plasma lighting, etc) zeolite filtration, and others cut from the cloth of quickly achieved nutrient free water, are bound to make their way into many reef systems.
A few years ago, the term ULNS, started popping up on aquarium forums, and in articles within some of our favorite magazines. The ULNS was described as an ultra-low nutrient system. It suddenly became a trend, and many aquarists were installing bio-pellet reactors, and zeolite reactors, in order to achieve what appeared to be a nutrient free reef. A few years have gone by, and the ULNS fad has had an effect on the hobby. Though, the term itself, ultra-low nutrient system, is very misleading. Do you need to have a ULNS, to be a successful reef aquarist? What’s the red tape, to converting your beloved reef, into a ULNS? Is this really the best way to learn and grasp the fundamentals of reef keeping?
Natural coral reefs:
Natural coral reefs are often described, in scientific literature, as nutrient deprived. This means, when a scientist tests reef water, they find no nitrates, no phosphates, or any other nutrient that would fuel the growth of algae, or impede the growth and development of corals. It’s this reason that corals remain, the greatest builders in the animal kingdom, constructing reef systems that can be seen from space. We see algae on natural coral reefs, even large patches of cyanobacteria, and there is argument amongst scientists, whether or not those are natural occurrences, or the result of climate change.
At any rate, reef water is clean and corals have adapted to this environment. Corals are tough, but they are susceptible to any dramatic change in water quality, or parameters. To understand what makes a ULNS attractive to a reef keeper, we need to understand how corals work. Both LPS and SPS corals use calcium, and other aquatic elements, to construct intricate skeletons. Both corals are communal, in the fact that a group of individual animals, work together, benefiting the whole. In reality, coral polyps are in symbiosis with one another. We know that coral tissue holds zoxanthellae algae. Scientists have now proven that corals, depending on species, get this algae from a parent colony at birth, or they collect the algae in their tissues as they grow.
Zoxanthellae is good, in that it offers corals sucrose as a byproduct of photosynthesis, and the sucrose helps corals quickly build strong skeletons. Zoxanthellae is bad, in that, it really is a foreign biological matter, within coral tissue. Under control and management, the relationship between zoxanthellae and a coral colony functions perfect. The algae is protected within the coral tissue, and the coral gets an extra boost of metabolism from excess sucrose.
When nitrate, or phosphate, are present in water, in any concentration, this fuels the growth of zooanthellae algae. First to discolor, are the coral’s protective layers of skin, which provide the bright and fluorescent colors we strive for. As the zooanthellae overtake the coral, it turns a uniform brown. Left unchecked, corals will actually expel the algae, bleach and likely perish. For this reason alone, nitrate and phosphate must be kept under strict control, without mentioning that phosphate impedes the calcification of coral skeleton.
The ULNS provides this nutrient free water, and allows corals to not only grow, but exhibit strong coloration. For the first time, we are seeing corals in the aquarium, which are far more colorful than their natural counterparts, largely thanks to ULNS.
Achieving a ULNS system
I want to be clear that natural reefs, nor reef aquariums, are ultra-low in nutrients. In fact, much ocean water is purified once in reaches the reef, and the reef lagoon, which is backed up by acres of mangrove forest. Like a refugium, these mangroves assimilate nutrients and provide habitat for young fish, invertebrates, etc. Coral reefs are very efficient at assimilating nutrients, and we need our reef aquariums to be just as efficient. A coral reef is one of nature’s perfect creations. Mangrove forests work in conjunction with microscopic algae to export nutrients, providing corals an environment to grow, which creates habitat for 80% of all oceanic life.
We often export nutrients, in the same way a mangrove forest does. By allowing macro-algae or marine plants, to uptake them during photosynthesis. This worked, but had some downsides. First, successful refugiums were filled with sand, miracle mud, live rock and marine plants. They are messy, and at times, some of that stray debris can enter the display tank. Debris such as sand, or mud, is harmful to sensitive SPS corals’ tissue, and mass tissue loss leads to the coral’s demise. Also, you could overstock an aquarium to a point, where a refugium could no longer keep up with nutrient export. Once that happens, you are back to square one.
We needed a place where both aerobic and anaerobic bacteria could flourish, offered natural habitat for marine animals, and encouraged the growth of tiny marine organisms. Our display tank does most of the work, offering natural habitat with live rock, and a place for tiny marine organisms, such as copepods to grow. They also are rich in oxygen, allowing aerobic de-nitrifying bacteria to flourish. Refugiums were picking up the slack, housing anaerobic bacteria and nutrient exporters, but had their limits.
When bio-plastics hit the scene years ago, like many, I was skeptical. There was nothing natural about a polymer that could be digested by bacteria. Suddenly tanks stocked to the hilt with fish, were turning up, with incredible coral population as well. Bio-plastics were beginning to bridge the gap, taking the place of the refugium, and allowing anaerobic bacteria to flourish, tossing away the need for a messy sand and mud.
Bio-plastics, or bio-pellets, were an important first step, in achieving the ULNS. Though, they had several downsides. The excess bacteria they produced could fuel cyanobacteria outbreaks, if the outflow wasn’t directed into a protein skimmer. While bio-pellets were great at exporting phosphate and nitrate, that is basically where their usefulness ended.
Zeolites are multi-porous elements found in nature. Industry uses them as absorbents and catalysts for various applications, and even produces synthetic zeolites on a massive scale. Given that they are the perfect home for anaerobic bacteria, and can naturally improve water quality, it makes perfect sense they made their way into the marine aquarium hobby.
In our aquariums, on one hand, zeolites function similar to bio-pellets. They give anaerobic bacteria a place to flourish. Though, unlike biopellets, zeolites cannot be consumed by anaerobic bacteria, so therefore they require a carbon source. In addition to giving anaerobic bacteria a home, zeolites naturally absorb certain nutrients from the water, while enhancing the effect of various additives.
The ULNS red tape.
If it sounds too good to be true, than it probably is, or isn’t, or might be. Zeolites do work, producing an efficient way to export nutrients, and heightening certain additives. The catch is, they require strict dosing. They aren’t a carbon source, so therefore they need to be supplemented with one. Partially they act as absorbents, so they require replacing, except if you replace all of them at once, you lose your super anaerobic filter. They work in conjunction with a powerful protein skimmer, which is essentially a requirement on a zeolite tank. Also, they require carbon to polish the water and reach that air standard of water clarity. Another thing, they aren’t cheap. The reactors, media and additives all add up quickly, and you can sink (no pun intended) a fair chunk of dough, getting a zeolite system up and running. Most of all, if not properly set-up and maintained, zeolites can harm, even kill your corals, causing sudden drops in nutrients and trace elements, along with fluctuating water stability.
Like a TV pharmaceutical infomercial, there is plenty of fine print. You can have a dream system, with air clear water and corals that seem to shine within the tank. Though, it’s going to take some elbow grease, and risk, to do so. Once, and if, you are successful, you have an efficient nutrient export system, that actually creates food for your corals. Did I forget to mention that, zeolites need shaken several times daily, to remove any organic sludge from the media. While it is a pain to remember to shake your filter media, the sludge provides a natural food source for corals.
Another paragraph of fine print about zeolite, it is so efficient in exporting nutrients, that often LPS corals, and even some SPS, require supplementation to thrive. Luckily there are a host of products, which not only replace any trace element exported or absorbed by a zeolite reactor, but enhance coral growth and coloration, even for LPS species.
So if I want ULNS, I need zeolites?
Wrong, ULNS has been around for years. While not always achieved with bio-pellets or zeolites, reef keepers have been exporting and absorbing nutrients in all sorts of ways. Algae scrubbers, refugiums, sulfur based de-nitrators, GFO, and many others have worked, and still work, to remove unwanted nutrients from our reef tanks. All of them carry their own set of pros and cons, and refugiums get a partially bad rap because they are so messy. In reality, a ULNS is simply an aquarium with undetectable amounts of nitrate, phosphate, and carefully monitored and supplemented for iron, potassium and other trace elements. How you achieve ULNS is really up to you.
What zeolite does, is allow you to keep a large fish population, feed plenty, and still have the ultra-nutrient free water, we find on the reef. For me, it allows aquarists to create more realistic home oceans. Coral reefs are densely packed, with lots of species diversity. In the reef aquarium, we may have a huge tank, capable of housing a lot of beautiful fish species, but were limited in the confines of what our nutrient exporter could handle. Zeolite, in some ways, has broken down that barrier, by exporting nutrients so efficiently, that additional bio-load is pulled out with everything else. It’s also not nearly as messy to add to an existing aquarium, as a large refugium or algae scrubber.
Is ULNS using zeolite right for me?
Setting out to implement a ULNS, using bio-pellets or zeolite reactors, isn’t for everyone, and especially not for beginners. You won’t really understand how the biological water cycle of an aquarium works, by adding a zeolite reactor. Yes, your new aquarium will cycle faster, and likely remain cleaner if you do so, but it’s important to have the underlying foundation, if you want to achieve long term success.
Also, zeolite requires a keen eye. You need to know how corals appear when they are healthy, and in good coloration. Since much of zeolite usage relies on the aquarist, making adjustments to cope with the appearance of the animals, a beginner might not know what to look for, adding too much of one thing, or not enough of another.
Zeolites are best used in the hands of dedicated and seasoned aquarists. They require a lot of work, and the dosing levels are constantly fluctuating, as you notice changes within your animals. There is no, “set it and forget it” to zeolite usage. You have to remain on top of your reactor’s performance, and from week to week, your dosing schedule will change, especially in the beginning. Also large, frequent partial water changes are a must, to replace trace elements that may be absorbed by the zeolites.
I’m new, what works for me?
For new, even intermediate level aquarists, I still recommend the lightly stocking, all natural approach to aquarium filtration. Using this, you will learn much needed restraint, patience, and aquarium principles, which no reactor or magic dust can teach you. While zeolite reactors can rush you through the ammonia cycle, and plant your feet toward clean water, the principles learned by traditionally cycling, stocking and caring for a reef tank, or more valuable than any filtration media.
If you’re an expert aquarist, with the time, money and drive to try something, albeit risky, then by all means, a zeolite ULNS might be the perfect natural progression for your reef. As home reef keeping progresses rapidly, (automatic dosing, computer control, LED lighting, plasma lighting, etc) zeolite filtration, and others cut from the cloth of quickly achieved nutrient free water, are bound to make their way into many reef systems.
Last edited by a moderator:
