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Is Keeping a Saltwater Reef Aquarium Difficult?
Saltwater reef aquariums can be a more challenging experience than the typical freshwater tropical aquarium. However, they don’t have to be so difficult that they are impossible to enjoy, even for beginners. If the excitement and wonder of reef keeping sounds like a challenge you want to undertake, here is some insight into what difficulties lie ahead and how to overcome them. The difficulty of keeping a saltwater reef aquarium is relative to three major factors: Your level of knowledge The types and number of organisms you plan to keep The size of the aquarium Fortunately, you can adjust the second and third factors to accommodate for factor one. As your knowledge increases, so can the complexity of your reef aquarium. If you’re asking how difficult a saltwater reef aquarium is too keep, you're probably thinking about starting your first one. Let’s look at the components of saltwater reef aquariums that give them the reputation of being more difficult. Initial Cost Chemical Relationships Biodiversity Maintenance Costs The modern saltwater reef aquarium can require more equipment, and therefore cost, than any other type of aquarium. I say “modern” and “can” because many successful reef aquariums are kept with minimal to no equipment. This however is not generally normal. Most reefers favor adding equipment to make their system easier to maintain and control. The chemical reactions that occur within a saltwater environment are complicated. There are many facets of saltwater reefing chemistry. Without proper respect or understanding of how these relationships can affect your system, you will find reef keeping to be more difficult than it needs to be. You do not need to be a chemist, however, to keep a saltwater reef. You just need to be an eager learner with a healthy curiosity. The biodiversity within the ocean is grander than any other ecosystem. Saltwater reef tanks have more biodiversity than most other types of aquariums. Understanding what organisms, micro and macro, live in your aquarium and how they will affect the ecosystem is crucial to keeping a successful saltwater reef aquarium. The continued maintenance of a saltwater reef aquarium is generally more expensive than other types of aquariums. Regular water changes involve a salt mix, and depending on the complexity of your reef, a number of other products, additives, and media may need to be replaced or dosed on a regular basis. Initial Cost of a Saltwater Reef Aquarium Most modern saltwater reef aquariums come with a higher initial cost than freshwater, fish-only saltwater, or brackish aquariums. This is mainly due to the extra equipment required to properly maintain a reef aquarium. High quality and intensity lights, a protein skimmer, and customizable filtration go a long way to ensure success with a reef aquarium. It is possible to build and maintain a saltwater reef aquarium without much equipment at all. However, a more advanced understanding of the chemistry and biology of the aquarium’s environment is usually required as well. Berlin style saltwater aquariums, for example, rely heavily on the natural bacterial populations to maintain a balanced aquarium. Generally, the equipment marketed to reef hobbyists is meant to increase the chance of success with our aquariums, and to make our lives easier. If the equipment you're buying doesn’t accomplish both of these things you should consider whether or not you actually need it. There is not a single piece of equipment I would recommend “skimping” on, or going with the cheapest option. If you want to lower the initial cost, consider decreasing the size of the aquarium, or limit yourself to animals that have less expensive requirements. For example, if a 90 gallon mixed coral reef turns out to be too much, starting with a 60 gallon soft coral tank and upgrading as you learn more is an excellent way to begin. Chemical Relationships in a Saltwater Reef Aquarium The chemical reactions that occur within a saltwater reef aquarium are complex, and affect nearly every aspect of your tank and the life within it. This may sound daunting, but you don’t need to be a chemist to own a saltwater reef aquarium. While the chemical relationships in saltwater are more complex and numerous than freshwater, the pre-made salt mix you buy does most of the work for you, at least at the beginning. Performing regular water changes, testing for, and understanding the basic parameters like pH, nitrate, phosphate, and alkalinity is the most chemistry you will do at first. If you are enjoying the hobby, you will learn its chemistry quickly. Perhaps the largest hurdle to owning a successful saltwater reef aquarium is the learning curve. There is an enormous amount of knowledge involved with this hobby. Thankfully you don’t need to know everything, or really that much at all, at least to begin. What you do need is a mentor. The most successful beginner reef hobbyists are those who found another successful hobbyist and mimicked what they did. They don’t have to be local or in person, maybe it's someone online or with a YouTube channel. Choose one person who has a successful tank, and just do what they did. An easy mistake you can make is cherry picking techniques, methods, and practices from multiple hobbyists. All aquariums are different. While many of them are successful, they did not take the same path to get there, and using methods from multiple setups can have disastrous effects. . Biodiversity of a Saltwater Reef Aquarium Coral reefs have the highest biodiversity of any ecosystem on planet earth. When we try to replicate this environment in our home aquariums, we invite hundreds and eventually thousands of species to inhabit and interact with each other inside our artificial ecosystem. These relationships and interactions become complicated quickly. The high biodiversity itself is not what makes saltwater reef keeping difficult. Not having the patience to allow these relationships and interactions to play out in their own time is what causes frustration in the modern reefer. For example, when you start a new reef aquarium, there is a series of microbial and algal succession that must occur. Initial organisms like bacteria begin to grow in the tank. They compete with other organisms like algae, and begin to overtake the aquarium at various speeds. The first week you may have brown algae (diatoms) covering your rocks. Eventually, the diatoms may be replaced by another type of algae a few weeks later, then another type, and another after that. The succession of algae and bacteria as the tank ages is completely natural. Eventually, the aquarium will balance, and your microbiome will establish. This leads to clean looking rock, sand, and glass, with only a minimal amount of algae growing, which your macro grazers like snails, urchins, and grazing fish like tangs and combtooth blennies, can take care of. To make this natural process happen quickly, you can add living, sustainable, probiotic bacteria blends to your aquarium. This will jumpstart and speed up the succession process by growing your microbiome faster. A healthy microbiome means less algae and pathogenic bacteria. Maintenance Costs of a Saltwater Reef Aquarium Saltwater reef aquariums are not cheap when done correctly. Maintenance costs scale with the amount of livestock in the tank. The more fish and coral you have the more supplements, food, and media you will need. Maintenance costs of a reef aquarium can come from the following: salt mix dosing supplements frozen food coral and specialty food chemical media mechanical media testing new or upgraded equipment When reef aquariums are full of fish and coral, they utilize resources in the tank quickly; sometimes faster than a water change can replenish them. In these cases, extra dosing of supplements in between water changes is necessary. One of the most expensive costs of maintaining a reef aquarium is the addition of the various supplements that must be replenished as they are consumed. Growing fish and coral also need a quality and varied diet. Fish and coral feeding regimens can be as simple or complex as you want to make them, but scale in cost quickly. Chemical and mechanical media are utilized depending on your bioload. A well balanced microbiome will prevent the use of expensive chemical media. There won’t be excessive nutrients to adsorb if your microbiome is established. Testing frequently is important with reef aquariums. Most home tests are fairly inexpensive. However, it is good practice to send your water to a lab for an ICP-OES test every few months. These are more expensive than home tests, but are not used as frequently. As your aquarium grows and you add more livestock, you will find yourself upgrading your equipment. Automated testers, larger protein skimmers, better lights, and media reactors are a few examples of possible upgrades. Depending on your initial budget, most of this equipment can be purchased initially and adjusted to your bioload as it grows. However, upgrading later to spread out the initial cost is also an option. Patience In my experience, the best way to make reef keeping easier is to have patience. Nothing in the saltwater aquarium environment should happen quickly, good or bad. Tank crashes and expensive solutions are usually a result of a lack of patience and trying to force or rush a solution to a problem. When in doubt, be deliberate, take your time, and heed the advice of a trusted mentor.
Cleaning Your Aquarium Part 4: Regular Water Testing.
The regular and consistent water analysis of your aquarium is the most powerful tool for a healthy and beautiful aquarium. Nothing is more effective at forming an accurate picture of your aquarium’s health than accurately and precisely testing your water parameters. Water analysis is only effective if done correctly. To get the most out of water analysis you must: Test the same parameters consistently Test regularly Chase trends, not numbers Use accurate and precise testing equipment and techniques The Importance of Testing Aquarium Water Regularly and Consistently. One of the pillars of the scientific method is consistency. In terms of aquarium water analysis, this means testing the same parameters at the same intervals, on a regular basis. In order to identify trends and patterns, we need multiple data points over a consistent and regular period of time. It is not enough to simply perform the occasional nitrate, phosphate, or pH test. These tests are only useful if you have a data set, taken over time, to compare it to. For example, if you're trying to determine the rate of nitrate build up, you might test nitrates before every water change. Or maybe you test nitrates once a month. Whichever frequency, or regularity, you choose, being consistent and testing at the same time, every time, is key. Being consistent to the time of day can be important as well. Some parameters, like pH, can fluctuate up and down throughout the day. If you test in the morning one day, and in the evening on another, you will see a misrepresentation of the actual daily fluctuation. Aquarium Water Analysis Reveals Trends You’ve probably heard to not chase numbers when it comes to aquarium water analysis. Chasing numbers means picking an “ideal”, sometimes arbitrary, metric for a certain parameter and then constantly trying to hit that target “ideal” metric by altering the chemistry of your aquarium with additives, filtration, water changes, etc. Trying to chase a specific number can result in more harm than good, and oftentimes is an impossible feat. A more effective method is to keep your aquarium parameters within a safe range and only take action when you see your parameters trending outside of that range. Trending can be defined as a parameter moving in one direction over at least three different tests, or data points. One or two tests do not reveal a trend, you need at least three tests to determine a pattern or tend. More data is usually better if that data is accurate. For example, there is no difference in the health of your aquarium between a calcium reading of 420 and 400. That difference could also be a testing error. However, if you test at 420, then 400, then 380, that could suggest your calcium is trending down and action should be taken to correct it. Which Aquarium Water Test Kits are the Best? Aquarium water parameter test kits can be divided up into hobbyist, professional, and lab grade. Hobbyist grade test kits have a wider range of error and rely on methods like colorimetry. Professional test kits are more affordable versions of lab grade tests. They use many of the same methods, but without the scientific grade precision. Lab grade test kits are much more accurate and precise. They use methods like ICP-OES, titration, and spectrophotometry. There is nothing wrong with hobbyist grade test kits. Just be sure to know the range of error when using these kits. For example, Hanna’s calcium test kit has a standard error of plus or minus 15 ppm. If you test calcium twice and the readings are different, but within 15 ppm, your calcium concentration may not have actually changed. This is one of the reasons we chase trends, not numbers. If your budget allows for professional or lab grade test kits, they can be a powerful tool. Some of these kits are more trouble than the sometimes minor increase in accuracy or precision is worth. In these cases, it may be better to choose a less accurate kit that will be consistently used rather than a more accurate kit that just sits on the shelf. Lab grade testing can also be done in actual labs through several companies via the mail. Utilize these resources as often as you like, but at least a couple times a year. This way, you’ll never miss that build up or depletion of an element you can’t test for at home. What Aquarium Water Parameters Should I Test For? There are many parameters which should be kept track of to maintain a healthy aquarium. Not every parameter needs to be tested at the same time. In general, the faster a parameter is capable of changing, such as salinity, alkalinity, or pH, the more often it should be tested. Parameters like nitrate and phosphate can be tested less often. Below is a short description of the most common water parameters to test for. Temperature As one of the most variable parameters, temperature should be constantly monitored. Using a thermometer, adhesive thermal-meter, or temperature probe attached to a monitor, the temperature of your tank should always be readily available and easy to read. The air conditioner being turned up on a hot day, a window being left open, or a busted heater can quickly change the temperature of your aquarium. Having a constant readout prevents dangerous fluctuations. Salinity In saltwater aquariums, salinity can change quickly over the course of just a few days. Salinity can be affected by neglecting freshwater top offs or dosing alkalinity and calcium. You should test the salinity of the aquarium before every water change to determine the salinity to mix the new water to. New water should be tested before being added to the aquarium as well. Freshwater aquariums should not have measurable salinity levels. Sometimes, freshwater aquariums can benefit from the addition of some sodium chloride. In these cases, the part per thousand should still read below one. Equipment Testing salinity can be done with a hydrometer, refractometer, or digital tester. Floating, glass-stick hydrometers are the simplest, most accurate, precise, and never need to be calibrated. Microbubbles can alter the readings of the plastic-lever hydrometers. Handheld refractometers can be precise and accurate, but only if you test multiple times and use perfect technique. Temperature, light angle, and sample volume can affect a handheld refractometer's readings. They also need to be calibrated before each use. Benchtop refractometers are generally more precise than their handheld counterparts. My personal favorite is a digital conductivity tester. These devices are accurate and precise, easy to read, and only need to be calibrated every few weeks depending on frequency of use. Regardless of which is your favorite, it is best practice to measure salinity with multiple methods to be sure your readings are accurate. My favorite combination is a glass,-stick hydrometer and a digital tester. pH In both freshwater and saltwater aquariums, pH can fluctuate throughout the day. As CO2 levels rise and then fall, its relationship with alkalinity causes pH to fall at night and rise during the day. Saltwater Aquarium pH pH fluctuations are important to monitor in saltwater reef aquariums. You need to know what your lowest point and highest point during the 24 hour cycle is. The smaller the fluctuation from 8.3, the better. For example, 7.8 at night and 8.0 during the day is considered a wide fluctuation and is too low from the ideal 8.3. Whereas 8.1 at night and 8.3 during the day, is the same fluctuation, but is much closer to the ideal number of 8.3. Testing however many times is necessary to determine how much your reef tank fluctuates is important. Consider starting with a pH test each morning, afternoon, and evening. For fish-only saltwater tanks, just test before each water change to see if your pH is drastically off from diminished alkalinity. Freshwater Aquariums The pH in freshwater aquariums should be tested before each water change to determine if it has changed since the last water change. Freshwater planted tanks that use CO2 injection should have pH monitored weekly and exactly 24 hours after CO2 levels are adjusted. Equipment Liquid reagent test kits for pH testing are the most common and easy to use. However, they can be inaccurate if the exact, correct amount of reagent isn’t used. Test strips are quick and easy, but can be difficult to read and have a low degree of accuracy. A digital tester that uses liquid reagents can suffer from the same pitfalls as any other liquid reagent test kit. My favorite method for testing pH is a handheld digital probe. While they need to be calibrated fairly often, depending on usage, they are more accurate, precise, and trustworthy. Single junction probes are great for freshwater and double junction probes are perfect for saltwater. Like with any test, I recommend using two different types of testing kits or equipment when determining the initial accuracy of your equipment, especially if you are using kits or equipment that can’t be calibrated with a standard solution. After you're confident the method you have chosen is accurate and precise, then limit the confirmation testing to approximately once a month. Alkalinity Much like with pH, alkalinity also fluctuates throughout the day. In reef aquariums, alkalinity is used up by corals during the day and dips at night. In freshwater, alkalinity remains fairly constant, but can fluctuate slightly when animals, including the microbiome, respire and release CO2. Saltwater Aquariums Alkalinity can be measured in reef aquariums as often as multiple times a day, or only once before every water change. The goal is to minimize fluctuations in alkalinity as much as possible. If you measure weekly, you will be able to correct alkalinity after it's been dipping for a week. This could be quite a large dip. If you measure every hour, you can correct on a much more precise level and the alkalinity in the tank will never measurably dip. The best practice is somewhere in between these two extremes. If you have very little livestock in the aquarium, start by measuring alkalinity before each water change. As you add more corals, your alkalinity will begin to dip more than 1 point in a week. When this happens, it's time to start dosing an alkalinity buffer in between water changes to keep your alkalinity stable. Be sure to test your alkalinity before each dose if you're dosing manually. If you are dosing automatically, begin by testing consistently and regularly. Start by testing alkalinity (1) when your lights come on, (2) half way through your light cycle, (3) when your lights go off, and (4) half way through your night cycle (or as close to it as you can get). These readings will tell you how much your alkalinity changes throughout a 24 hour period. Use this data to adjust how much and when the buffer is dosed in order to shrink the fluctuations as much as possible (preferably within 2/10ths of a degree). Once you have a week of consistent data, and you're confident your alkalinity isn't fluctuating too much in a 24 hour period, then you can pull back on testing to between once daily and once weekly. Freshwater Aquariums Alkalinity only needs to be measured before each water change in freshwater systems where the alkalinity is stable. This reading will inform you of how much alkalinity buffer to add to the new water. If heavy feeding leads to high rates of decomposition and therefore large bacteria populations, testing alkalinity in between water changes may be necessary to determine if dosing is necessary. Equipment For freshwater systems, a basic titration kit is sufficient. For reef aquariums, I would suggest a liquid colorimeter test kit, or a quality titration test kit. There are also automatic water analyzers available in the reef hobby that will automatically test, via titration, alkalinity, calcium, and magnesium on a set schedule, multiple times a day. If one of these testers is in your budget and you are automatically dosing any of these testable parameters, I recommend getting one. Calcium & Magnesium Freshwater Known as general hardness (GH) in the freshwater aquarium, calcium and magnesium are used by plants and animals at a relatively low rate. Best practice is to test for these elements via a titration GH test kit before each water change to ensure new water has been treated appropriately. Saltwater In the reef aquarium, calcium and magnesium are highly important. Depending on how many corals you have, and whether or not you are dosing, it's a good idea to test for these elements, individually, at least once a week, or daily if you have many corals using lots of calcium and magnesium. Follow the same testing guidelines for alkalinity when testing calcium and magnesium. Like with alkalinity, corals will uptake less calcium and magnesium at night. The amount and timing of your dosages are important to monitor. Testing multiple times a day, at the same times initially, will give you an accurate and precise dosing schedule. Calcium and magnesium fluctuations do not affect coral growth as much as fluctuations in alkalinity. While these parameters should remain relatively stable, they do not need to be dialed in to the degree that alkalinity does. Equipment For freshwater, the basic 1-part liquid reagent test kits for general hardness (calcium and magnesium) are sufficient. For saltwater reef aquariums, I recommend either a liquid/powder colorimeter or a titration test kit for each element separately. Like with alkalinity, there are automatic water analyzers available that will take multiple readings per day. Ammonia & Nitrite Ammonia and nitrite are most associated with the nitrogen cycle. Most people don’t bother testing for these compounds after their tank is cycled. This is mostly true for nitrite. As the second stage in the nitrogen cycle, it is the shortest lived and is rarely measurable after the nitrifying microbiome is established. Ammonia on the other hand is a direct byproduct of fish waste, fish respiration, excess food, and even underperforming RODI filters. Some systems even have limited nitrifying bacteria and every time you feed, a measurable amount of ammonia is present. For these reasons, it's a good idea to test your ammonia/ammonium levels every month. If you have ammonia present, it's a good idea to look at how much habitat for nitrifying bacteria you have, if you're feeding too much, or if your RODI filter is letting ammonia or chloramines (which can read as ammonia) through the membranes and resins. Equipment In most cases, a 2-part liquid reagent test kit will suffice for ammonia and ammonium measurements. However, whenever I detect considerable ammonia or ammonium levels when I wasn’t expecting them, I always confirm with a higher quality liquid reagent kit that separately tests for total and free ammonia. Nitrate & Phosphate These two molecules are some of the most debated pieces of chemistry in both the fresh and saltwater hobby. Regardless of where you land on how much of each should be measurable, the principle behind their production, accumulation, and measurement is the same. Nitrate and phosphate are considered inorganic when they are free-floating in the water column. This is when they are measurable by our testing kits. Nitrate and phosphate are organic when they are attached to biological organisms (inside bacteria) or as part of other organic material (fish waste). Nitrogen (especially in the ammonia and ammonium form) and phosphorus are more biologically useful in that they are more easily absorbed by animals and plants than nitrate and phosphate. We can estimate the amount of nitrogen and phosphorus in the aquarium by measuring the nitrate and phosphate. The exact desired concentration of nitrate of phosphate is different for every hobbyist and every aquarium. However, measuring these nutrients at least once a month will prevent build up beyond undesired levels and allow you to notice trends, whether good or bad. Personally, I test for nitrate and phosphates at least once every two weeks, at most once a week, or once a month if I've been showing stable readings. Equipment For general readings with a desired accuracy less than 10 ppm for nitrate, I recommend a 2-part liquid test kit. For all phosphate readings, and nitrate readings with a desired accuracy less than 1 ppm, I recommend a powdered reagent colorimetric test kit, such as the Hanna checkers. Potassium, Iron and Other Trace Elements Freshwater In the freshwater aquarium, potassium and Iron are important elements for plant growth. If you have fast growing plants, getting a potassium and iron reading every month or two is not a bad idea. If you're not fertilizing a heavily planted or fast growing planted tank, you're definitely low on both of these elements. If you are dosing fertilizers, knowing how much to dose is important. Other trace elements in the freshwater aquarium are ideally replenished when new water is treated with a remineralizer, an all-in-one fertilizer, or trace fertilizer; and therefore don’t need to be tested. These include elements like molybdenum, zinc, nickel and others. Honestly, I would test for these elements if I could. However, a reliable, inexpensive test kit for these elements suspended in a liquid solution is not readily available. In lieu of testing, adding trace elements as directed, then adjusting based on visual analysis of deficiencies is best practice. Saltwater In the saltwater and reef aquariums, all these minor and trace elements are in the salt mix and are replenished to a degree with every water change. If you have growing corals and are dosing alkalinity and calcium, you're probably using trace elements at a rate faster than they can be replenished with a water change. If this is the case, it's a good idea to test for these micro and trace elements right before a water change using an “ICP-OES” lab-grade test. These should be done approximately every three to six months to check if you're deficient in minor or trace elements. They are also useful in determining if you have contaminants in the aquarium. Liquid reagent test kits for potassium and iron are available for freshwater and saltwater aquariums. Test kits for strontium are also readily available for saltwater. Lighting One of the most crucial elements of a saltwater reef or freshwater planted tank, light rarely gets measured the way it should. Knowing the intensity, spread, and quality of your photons will allow you to accurately and safely place corals and plants while avoiding too much or too little light in the tank; leading to bleaching or excessive algae growth. Accurately testing your light’s photosynthetically active radiation (PAR) can be costly; the tools to do it right can cost over $600. However, if you know someone with a submersible, lab-grade PAR meter, or a way to rent one, it is well worth it to measure your PAR and adjust your lights as necessary. If done correctly, you should only have to make this measurement once as you will rarely have to move or change your lights unless the aquarium or the aquascape changes. This may be an expensive measurement to make, but you should only have to make it once. Be sure to record your PAR readings as you make them across your tank. When you add new plants or coral, you will know the best place to put them per their requirements. Photosynthetically Useful Radiation (PUR) is just as important, if not more so, than PAR. PUR is essentially the intensity of the individual spectrums of light, not the intensity of all the spectrums together (PAR). PUR measures the quality of your light, what is actually photosynthetically useful vs just the quantity of photons (PAR). Corals, for example, love bluer light near the 420 nm range, while plants prefer a more intense red part of the spectrum. Unfortunately, there is no hobbyist-grade, readily available equipment as of yet that can test for PUR. The best practice is to research your animals and plants, know the spectrums they need, and adjust your light’s individual spectrum intensities to match that research. CO2 In freshwater high-tech planted aquariums, CO2 gas is injected directly into the aquarium. The rate at which this gas is injected is different for all aquariums. No matter the setup however, the parts per million (ppm) should be between 20 and 30. Once you achieve this concentration, you shouldn't have to re-measure CO2 again unless you adjust the CO2, or just want to confirm your injection rate every once in a while. There are two ways to measure CO2. The first is to take a KH measurement and a pH measurement then use this table to find your CO2 concentration. The only issue with this method is you can get false readings if there are any other factors besides pH or alkalinity (KH) that are affecting the CO2 concentration. For example, some shrimp salts and pH buffers will give you a high, false CO2 reading because they lower the pH without lowering the KH. The second way is to use a two part liquid test kit and measure the CO2 concentration directly. This method is the more reliable of the two, but requires another test kit, although they are fairly inexpensive. Visual Testing Testing kits and equipment are a vital tool to understanding our aquariums. They can also help us diagnose and track problems and solutions we may be experiencing. The easiest, and sometimes most reliable test we can perform, is a visual assessment. It is crucial to set aside all the kits and equipment and visually observe the aquarium regularly and consistently. Take additional time to deliberately observe problems you've been having, and the growth or recession, health, behavior, and color of your livestock. Note the algae growth, the flow, and amount of detritus build up. Go beyond just looking at your aquarium as a normal part of enjoying it. Make intentional observations, note them down, and relate them to the maintenance you have been performing. Experiment Every aquarium and aquarium hobbyist is different. There are a thousand ways to test your aquarium’s parameters correctly. Different regimens, schedules, and testing equipment work better for different hobbyists. In the beginning, don’t worry as much about being perfect, just be accurate, precise, and consistent.
Stability and Increasing Coral Growth in the Reef Aquarium
Stable water parameters are paramount to coral health, beauty, and growth. Stability is only one of many important factors that contribute to these conditions. After the nitrogen cycle is complete, and all water parameters are within their safe ranges , keeping them stable within those ranges is probably the most important contributor to stress free, healthy, beautiful, and growing coral. Obviously, light, flow, regular feedings, and space are equally as important in their own way. Those multifaceted factors will be discussed in a later article. Here and now, I’ll focus on the benefits of stable water parameters. Why are My Corals Not Growing? The reef aquarium can never be an exact replication of the reefs in the oceans. It's just not possible to perfectly replicate the near infinite elements of that massive ecosystem. Instead, we should strive to make our home aquaria sustainable, artificial ecosystems that mimic the natural reefs as much as is beneficial. The foundation on which we build that artificial ecosystem is stability of accurate water parameters. While we may never exactly match the light, nutrient flow, or grazing prowess of a natural reef, we can build a healthy system on one of the ocean’s most powerful and most easily reproducible characteristics, its stability. There are a million reasons why the corals in our aquariums may not be doing as well as we would like. From disease to improper environment and macro-pests, the specific reason or reasons why some of your animals may be experiencing difficulty are too numerous to delve into in this article, but I'll provide a few examples. Poor water condition Parameters outside of safe ranges Improper lighting Improper Flow Disease Macro-pests (irritation) Lack of Food Aggression While these examples can affect coral growth, my intention here is to discuss one of the major inhibitors of coral growth, unstable, or inconsistent water parameters. What is Stability? Stability is relative, even in this context. Some may consider a daily temperature fluctuation of two degrees Fahrenheit stable. Others classify anything outside of a half degree fluctuation as unacceptable. While half a degree is technically more stable than two degrees, it is more difficult to achieve, thereby making it impractical. Two degrees in temperature is also too wide of a fluctuation and in most cases one degree is just as achievable and more stable. My point is stability is not just about reducing the fluctuation. It's also about what is practical. If you can’t maintain a half degree stability with any consistency or reliability, then does it really qualify as stable? Stability is keeping a parameter from fluctuating outside of a given range in a practical method that results in consistency. Which Reef Aquarium Parameters are the Most Important to Keep Stable? The most important parameters to keep stable in the reef aquarium are: Temperature Salinity pH Alkalinity Calcium Magnesium Lighting Nutrients Flow Why Stability is Important for Increasing Coral Growth Most ecosystems in the ocean are stable. They have the same pH, temperature, alkalinity, macro, and micro element levels. They experience the same lighting, nutrient, and flow regimes daily. In the aquarium, we have seen many examples of the results of stability. Corals that have a stable environment don’t have to spend energy constantly adapting. This results in less stress, better health, immune systems, and ultimately faster growth. There are factors that are not stable as I defined it earlier, such as nutrient flow. The amount of nutrients, the form it comes in, and exactly when it comes can vary daily. However, the fact that at some point nutrients surge through a reef multiple times a day, every day, does remain consistent. When considering consistency and stability, sometimes we need to “zoom out” from a microscopic or minute by minute view to see how stability still applies, just on a larger scale. For example, temperature should be maintained constantly. Coral feedings and nutrient flow, on the other hand, achieve stability by occurring at the same time daily, not every few minutes like the switching on and off of a heating element. Although this is relative to your aquarium. Systems with lots of fast growing corals can be fed multiple times a day with massive nutrient export systems. Achieving Stability Achieving stability is all about knowing the acceptable and practical range you want to keep your given parameter within, and implementing the proper methods and technology to achieve that. The first aspect, knowing the acceptable and practical range, can be relative, like I mentioned earlier, but the key is to know what works with your tank. We’ll get into it with each parameter later, but some aquarists keep their alkalinity at 10, others at 7. Stability would not be keeping it between 7 and 10, but as close to whichever number you choose as is practically achievable. The second aspect, implementation, is extremely nuanced with several viable methods, each with their own advantages and disadvantages. I won’t go into detail on each one. I’ll simply list them so you can explore each one in more depth at your leisure. Playing the Long Game Once you have achieved a consistent and stable range of parameters you are happy with, the rate of coral growth won’t happen overnight. It may still take several months before your corals adapt to stable conditions and begin to grow faster. Don’t forget, stability is but one aspect of Increasing coral growth. Nutrient intake, lighting, flow, and many other factors play a large part in coral biology as well. Stable Water Parameters in the Reef Aquarium Temperature Keeping your temperature stable is probably easier than the other parameters, and just as important. You should strive to keep temperature fluctuation within 1 degree Fahrenheit. If this proves too difficult for your system, 1.5 degrees is still better than 1, but anything over 2 degrees of fluctuation can begin to stress more sensitive creatures. When performing water changes, try to heat up the new water to the aquarium temperature, especially when performing a water change larger than 10%. The easiest way to achieve temperature stability is by utilizing a controller for your heating element. Some heaters are efficient enough to keep temperatures stable using the built in thermostat. However, installing a heating element, attached to a separate controller with at least two temperature probes attached, is much more reliable and consistent. Two temperature probes allow for a more accurate reading of the aquarium's actual temperature. The controller gives more precise control over the on/off reaction times of the element. Choosing a controller that allows multiple elements to be installed also guarantees a more significant, and therefore consistent heat distribution throughout the system. Salinity Animals that live in aqueous environments are constantly undergoing osmosis and diffusion. This means, they are always balancing the concentration of water, and the solids dissolved in it, inside and outside of their tissues. If the concentration of the major dissolved solids (in this case salt) in the water is constantly changing, then the animals become stressed by spending too much energy trying to correct these changes in concentration. Additionally, water moves through the tissue via osmosis, which takes no metabolic energy, but can still significantly affect the concentration of other dissolved solids, causing stress on the animal. However, if the salinity is always the same, the animals can spend their energy on their immune system, growth, and other metabolic functions. There are many solids dissolved in seawater, but salinity is the measure of NaCl, sodium chloride, which makes up nearly 70% of seawater. Keeping salinity stable is far more important than alkalinity, calcium, magnesium, trace elements, and organics. Once your salinity is stable, then you can focus on the lesser concentrated solids in the water. Why Would Salinity Change? Salinity can change for many reasons. The most common and quickest to occur is evaporation of water from the tank, resulting in a rise in salinity. This is easy to offset by adding RODI, or non-salinized freshwater, back to the aquarium, at the same rate it evaporates. This can be done manually, by pouring freshwater into the aquarium from a storage container, which is sealed when not in use, or as you make it. Marking where the top of the water level should always be in your aquarium, allows you to refill to that mark consistently as the tank water evaporates. Another option is to install an automatic top off. This method, once installed, takes care of itself. Some versions still have a reservoir that needs to be refiled. Other versions hook directly up to the RODI system. The latter is not as safe as having a top off reservoir, because if the float valve, water sensor, and its backups fail, the RODI system will continue to feed water into the aquarium indefinitely. A reservoir will only dump the reservoir’s amount of water into the tank if it fails. Salinity can also change when the new water mixed for water changes is not accurate. When performing water changes, always recalibrate the tool you use to measure salinity. Measure the salinity of the aquarium and the new water. If your tank reads high, lower the salinity in the new water and vice versa. For example, if your tank is at 36 ppt and you want it at 35 ppt, and you are doing a 10% water change, then the new water needs to be at 26 ppt. If you're doing a 50% water change, then the new water should be mixed at 34 ppt to bring your tank to 35 ppt. That's just the math though. It is more practical and safer to adjust salinity slowly over several water changes. Another common way salinity can change is if you are dosing sodium bicarbonate or sodium carbonate with calcium chloride. As the animals use the bicarbonates or carbonates and the calcium, the sodium and the chloride combine into sodium chloride (salt), and raise the salinity. There are several ways to go about correcting this, the most common is the method from above. Measure the salinity of your aquarium before your water changes and mix the new water to the correct salinity to bring your aquarium back down to 35 ppt. If your salinity is climbing because you're dosing these two compounds, be sure to research the “Balling Method” for 2 part dosing. There is some interesting chemistry behind what happens to your trace elements and magnesium levels when you are 2 part dosing calcium chloride and carbonates and then correcting for the salinity change. If you don’t add trace elements back into the aquarium, then you will reduce them indefinitely. pH A stable pH helps stony corals maintain a strong, dense skeleton. There have been decades of multidisciplinary research and studies on pH stability in the ocean. pH is a standard metric used to measure ocean stability. In the reef aquarium, we are coming to realize maintaining a pH range of 7.8 to 8.3 throughout a 24 hour period is just the beginning. While 7.8 to 8.3 is the safe range, closing that gap to 8.25 plus or minus a tenth of a degree, or better yet, 8.3 for 24 hours, is exponentially better for coral health and growth. There is still much research left to be done concerning the relationship with pH and coral health in the reef aquarium. Although, what we have discovered recently suggests stable pH as close to 8.3 as possible has a much larger affect on coral health than we thought. pH stability is its own article. However, there are some easy ways to close the gap, all else being equal. First, if you have a refugium or plan to set one up, the photoperiod on your light should be the opposite of the display tank's light. Photosynthesizing macroalgae will absorb CO2 at night, preventing the pH from dropping significantly. Another common cause of low pH or pH instability is too much CO2 in the air around the tank. Running airline from the skimmer to the outside or opening a window can bring CO2 levels down. Stable alkalinity can also help with maintaining a stable pH. Alkalinity The capacity by which a body of water can maintain a stable pH through the neutralization of acids and bases is what we are measuring when we test for alkalinity. For most of us with a reef tank, this means the concentration of carbonates and bicarbonates in the water. Corals and other microfauna utilize carbonates as part of their biology. When they absorb carbonates from the water, their concentration lowers, thus lowering the alkalinity. Alkalinity can also lower when carbonates are combined into other compounds, such as with CO2 gas. The alkalinity is replenished with water changes and dosing carbonates and bicarbonates directly. The key to stable alkalinity is not to just replenish carbonates weekly or every couple weeks in one huge dose, like with a water change, but to add them at the same rate they are used as often as possible. Most of the aquariums I maintain receive a dose of sodium bicarbonates multiple times a day; usually a minimum of two. Aquariums with a relatively high population of stony corals can drop in alkalinity by as much as two or more degrees of carbonate hardness (dKH) in a week. That's nearly 0.3 degrees a day. By adding the appropriate amount of sodium bicarbonate to raise the alkalinity of the tank by 0.15 degrees twice a day, the most the tank will fluctuate is .15 degrees instead of two degrees. In terms of maintaining stability for coral health and growth this is an incredible difference. The easiest way to dose carbonates for consistent alkalinity is to use a dosing pump. These range from simple single headed pumps that can plug into mechanical or digital outlet timers to highly programmable multi-pump dosers. Whether you choose a simple single-headed doser, or a programmable apparatus with a built in computer, they are both means to the same end, stability. Calcium & Magnesium Without getting too much into the nuance of the chemical relationship between alkalinity, calcium and magnesium, the main take-away is calcium and magnesium can be dosed similarly to alkalinity. Corals utilize calcium and magnesium just like carbonates. The more often you replenish calcium and magnesium, the more consistent their concentrations will be. There are a couple things to consider when dosing these elements with carbonates. Briefly, I will mention that when dosing alkalinity and calcium, they should not be dosed at the exact same time. Also, the Balling Method, mentioned in the salinity section above, also applies here as the rise in salinity mentioned is a result of dosing sodium bicarbonate or sodium carbonate with calcium chloride and results in a trace element deficit over time. Light Recently, we have begun to discover that corals are capable of adapting the types and concentrations of their light sensitive pigments and chlorophyll. Even though corals are highly adaptive, this process is biologically expensive. Even if your lighting is not ideal, your corals may compensate over time. However, setting your lights to an appropriate intensity and spectrum for the livestock in your tank, and not altering it after, is paramount to stability. Use a trusted PAR meter and the spectrum information, or available settings, on your light to determine what is the best scheme for your setup. Find a fellow hobbyist with a similar and successful tank to yours with a working lighting scheme, or use the presets in the app if your light comes with one. Intensity and spectrum are both important. Nothing beats using a PAR meter to measure intensity. Spectrum is a little more difficult. All we really have is what the side of the box says or the adjustments available in the app if your light has one. The details on exactly what spectrum to favor is for another article. Suffice it to say, corals prefer a higher intensity around 420 nanometers (blue), but still require a lower intensity across the spectrum (white). Minor adjustments over the course of the life of the tank, even larger ones at the beginning are fine. The constant altering of your light's settings on a weekly or even monthly basis are what leads to instability and coral stress. Remember, even if your lights are not ideal, your corals will adapt. It is adapting constantly from frequent changes that can be detrimental to coral health and growth. Nutrients and Flow Stable nutrients (organic particulate matter) and flow work a little differently than the above parameters. Consistency in schedule is more important than constant stability. Unlike the parameters above, nutrients and flow should fluctuate over the course of a day. Stability is achieved by feeding the same time every day and by having the same flow patterns at the same time every day. For example, with flow, you may have a pulsating pattern at 20% for most of the day, then a feed mode at 7 pm, then a high nutrient pulse for 2 hours at midnight. Stability in flow means keeping this scheme or schedule of patterns the same every day. In the ocean, flow changes throughout the day, but the intensity and pattern is fairly consistent at the same times. The same is true for nutrients. Both fish and coral can anticipate feedings by the “time of day” or the light intensity if you feed at the same time everyday. Coral will extend feeding tentacles and are more receptive to incoming food particles. Slow and Steady Maintaining stability and consistency in water parameters is crucial to coral health, growth, and beauty. While achieving stability is important, any changes made in a reef tank must be done slowly. Unless it is an emergency, like extremely high temperature, salinity, or pH, altering your parameters to the range of numbers you want, then keeping them stable within that range should take time. Aquatic life is particularly subject to the environment it lives in. Changes in the concentration of elements and compounds in the water quickly and significantly impact the biology of aquatic organisms. Making these changes slowly, even if they are for the better, is important to reducing stress on the organisms.