Beginner Topic A Beginner’s Guide to Reef Aquariums

A Beginner’s Guide to Reef Aquariums
By Reefer Matt


Reefer Matt’s First Reef Tank! Circa 2005

Preface: This article is a beginner’s guide to reefing and does not encompass all aspects of the reef aquarium hobby. It is meant to be a basic guide to get started in reefing. All information is based on the opinion and experience of Reefer Matt, and your results may vary. Happy Reefing!

So, You Wanna Be A Reefer!
Reefing, or reef aquarium keeping, is a wonderful hobby for those daring to try. It is challenging and rewarding, yet relaxing and exciting. It encompasses every emotion, and gives us a unique glimpse of our wonderful salty friends. If you are thinking about or just starting your reefing journey, you will soon find an ocean of information. It may also appear that there are no definitive answers to your questions. I hope to help.

You As A Reefer
Reefing is as unique as the Reefers themselves, and only a few basic things are paramount to success. The rest are opinions and beliefs that were gained with experience or bred by rumor. As you begin your research, know that reefing can be as complex or simple as you wish. A first consideration may be to look at your lifestyle. Are you an active, yet patient person? Or are you lax, yet quick tempered? Knowing yourself can help you decide if a reef tank is right for you, and which type of inhabitants are a good fit. Reef tanks require patience, and can take months to properly set up, cycle, and stock. Reef tanks require stability. A willing attitude to do the work required will go a long way to a successful reef. And let’s not forget, yes, reefing does require some disposable funds. However, many budgets can be accommodated in reefing.

The “Tank”
In reefing, we typically refer to the aquarium as a “tank”. It’s usually the first thing people think about. What size, material, and how much is it going to cost? From my experience, the tank is the least expensive part of reefing. After a few years, the coral, fish, and equipment can dwarf the cost of the tank itself. But there are certainly exceptions! The usual suggestion is to get as big a tank as feasible, because the more water volume, the more stable it will be. This is true to a point. Larger tanks usually require more equipment and often more work to maintain overall. Running costs are also increased in larger tanks. I suggest getting an aquarium that is at least 40 gallons. It should also be configured to be comfortable for you to maintain, while you gain experience in the months and years to come. If maintenance is hard, it likely won’t get done.


Reefer Matt’s 75 gallon SPS tank at about a year old in 2020. This tank size was a good choice based on size and affordability at the time.

After you have decided on a tank, a mountain of equipment stares at you. Soon you may realize that you are not a millionaire (though it would be nice!), and suddenly feel deflated about having a reef tank. Before you start buying equipment, don’t get discouraged! I suggest visualizing the filtration and life support for your tank inhabitants as best you can. Buying new or used gear is up to each Reefer, and there are risks and rewards of each. There are many online resources to help you do this. Some basic equipment required for a reef tank includes: the aquarium (aka tank), a circulation pump, wavemaker, heater (or chiller, depending on home temperature), protein skimmer (in many cases), and lighting. For a new tank, dosing pumps and controllers are usually not needed for many months, if at all.

When it comes to lighting, you do not have to buy the most expensive option available. But do understand that while lighting is a personal choice, many Reefers have purchased certain lights to start, only to buy higher quality ones later. Which brand is a subjective matter and up to each individual Reefer. Proper research into what each light does, along with its spectrum and PAR (Photosynthetically Active Radiation) will help you determine which light will fit your reefing goals. You can always dim down a light that is too bright but cannot go past 100% intensity on a light that is too small. Used equipment can usually be found in abundance, and is a great option for all Reefers.

Aquarium heaters haven’t changed much over the years, but there are a few suggestions I have for them. The first, is to get one properly sized for the tank. Bigger is not always better, as a large heater that fails on can overheat a tank. A heater that is too small will constantly stay on, and may not be able to properly heat the water. Heaters do fail, and they usually fail at the most inconvenient time. So, getting the properly sized one is important for your reef. Also, a heater controller is highly recommended. They help regulate temperatures by turning the power to the heater on and off, and can also alert you. I use heaters with a built-in thermostat, and back them up with a heater controller that is set a couple of degrees higher. Your home temperature is the main heating and cooling of the tank. The heater or chiller is adjusting it by 5-10 degrees past that.

Now that you have your tank, your lights, and your heater, onto the return pump and wavemaker. These are personal preference, and there are many options. I suggest researching one in your price range and getting one that will create the flow you desire. As with lighting, it is possible to ramp down bigger pumps, but not ramp up past 100% on smaller ones. Be aware that a pump that is too big may not be preferable either. There is a thing as too much flow, and a huge pump at 10% may be too much. Trial and error may be required at first to find pumps suitable for your tank. To assess the flow in your tank, you can use an air stone and air pump to put bubbles inside to see the pattern.

Protein Skimmers
Protein skimmers are something that may or may not be required, depending on your tank chemistry and nutrient export strategy. What they do is remove organics (fish poop, uneaten food, etc.) from the water before it can break down into ammonia, nitrite, then nitrate. A skimmer may not be needed on a new tank for at least 1-2 months, depending on the bio load. However, in many cases, a skimmer is beneficial and has other perks like water aeration.


The original “black box” lights for the 75 gallon SPS tank. Though able to grow coral, I wanted better coloration and depth for the tank, and later chose Kessil lights.

I highly recommend using rodi (Reverse Osmosis Deionized) water for your reef tank. There are many budget options available. Tap water can contain impurities that harm invertebrates and coral. Also, which salt mix you use will largely determine the main water parameters for the tank. I suggest finding one in the range you would like your tank to be in. And for topping off a reef tank for evaporation: Salt doesn’t evaporate, water does. Make sure to only use the same high purity water to top off your reef as you do in the salt mix.

Water Parameters
For main water parameters, I suggest the following ranges:
Temperature: 77 - 80F
Specific Gravity: 1.024 -1.026
Alkalinity: 7.5 - 9 dkh
Calcium: 375 - 475 ppm
Magnesium: 1300 - 1450 ppm
Nitrate 1 - 35 ppm*
Phosphate .04 ppm - 0.1 ppm*

Note: It is possible to keep a successful reef aquarium outside of these ranges, these are merely my suggestions.

*Varies on species kept. Algae may be a nuisance at the higher levels without a strong CUC.

After you have settled on your equipment and set up the tank, the fun now begins! The waiting. Cycling is the process of growing nitrifying bacteria. These bacteria act as the main filter in a reef aquarium. They live on and inside the rockwork of the reef aquarium. They convert ammonia, which is toxic to livestock at higher levels, to nitrite, then nitrate. There are also bacteria which convert that nitrate to nitrogen gas, thus completing the cycle. Many reef aquariums do not have enough anaerobic bacteria to convert all nitrate to nitrogen, so it usually ends with excess nitrate formation. However, a refugium (fancy word for growing algae in a specific place) with macroalgae can remove some of the leftover nitrate as well.

Depending on which choices you make about rock and sand, it may take a few weeks to properly cycle your tank. It could also take as little as a few days if using live rock. Using live rock (rock from the ocean or an established tank) and live sand is the quickest way to cycle a reef tank. New dry rock, or dead rock, has little to no beneficial bacteria in it for reef tanks. Tanks with dry rock and no sand are difficult to establish a cycle, and usually recommended for experienced Reefers, but still possible. The rock is the main filtration for the reef, and if it starts off sterile, it can take several weeks to a couple months to gain a sufficient bio culture in it. Adding a bottled bacteria product can help speed up the cycle time as well. Testing will determine when the cycle is complete.

Test kits and tools for various water parameters like Ammonia, Nitrite, Nitrate, and salinity are needed at first. For cycling a new tank, I suggest waiting about 4-6 weeks before testing for ammonia, nitrite, and nitrate if new dry rock was used. For live rock, the tank may be quickly cycled in as little as a few days. In that case, checking for nitrate in a week or two may be sufficient. If doing a fishless cycle (I highly encourage this), I suggest feeding the tank as if there were a couple small fish in it. This will feed the bacteria and help establish the cycling process. Checking nitrate levels will confirm the cycle has been established. Every tank is different, and cycle times will vary.

After cycling is complete and testing ensures little to no ammonia is present, and nitrates are elevated, a water change can be performed. Then the first fish can be added! A few weeks later, your first coral! Slow and steady is the key here. Every new addition will add more bioload to the tank. Adding them too quickly can cause problems like a spike in ammonia. The bacteria will grow and adapt to the bioload. You are on now your way to a happy reef at this point!

The Uglies
After you have been reefing for a few months, you may start noticing “algae” problems and wonder how to correct them. Algae, diatoms, and cyanobacteria may appear and send you into a panic. There are many potions and elixirs marketed to target such problems, and some of them may work. However, knowing what caused the problem will aid in preventing it in the future. New tanks usually get diatoms, for example. Knowing this is normal and will likely go away can set a new reefer’s mind at ease.

Algae outbreaks may just need a larger CUC (clean up crew) of snails, hermits, urchins or stars. A strong CUC will keep your tank looking clean, and is a vital part of its ecosystem. I suggest one critter per gallon of tank size in a fully established reef tank. So a 40 gallon tank may require 40 little mouths to keep it clean eventually. I suggest adding a small CUC after about a month or two past the cycle. Then increase the numbers as needed. Certain fish like tangs and rabbitfish help as well, but should only be put into a suitably sized tank.


Reefer Matt’s main fishy pal, Puffy! “He” is not suitable for a reef aquarium, and lives in a fowlr tank.

The Fish
Fish are another topic where it’s “viewers choice”. I suggest researching the care requirements for every fish you want before purchasing. These are not the animals we want to buy on impulse. Some of them are not compatible for a reef aquarium. Looking at you, large lionfish, puffers, and (some) angelfish! I personally like clownfish (Nemo!), cardinalfish, and the “nice” damsels like the Lemon Damselfish.

The Coral
Let’s not forget the coral! After your tank is cycled, and fish have been in it a few weeks, coral can be added! I suggest starting off with some soft coral. They are more forgiving, and usually lend more success while you hone your new reefing skills. After you are comfortable, and can keep them alive for many months, consider LPS (Large Polyp Stony) coral. Some favorites of mine are Candy Cane, Duncans, and any of the so called “Favia” coral. After about eight to twelve months of reefing, you should have a good understanding of tank chemistry, and how to keep it stable. If you are interested, this is the time to consider “beginner” SPS (Small Polyp Stony) coral. Montipora, Leptoseris, Pavona, and the Green Slimer acropora are all good choices here. In time, you’ll gain more and more confidence as you progress through your reefing journey.


Some Zoanthids from one of Reefer Matt’s reef tanks.

Slow is Fast
Nothing good happens fast in reefing, and patience is the key to a successful reef tank. It is important to remember that a reef tank is not a motorcycle or a sports car. It does not sit idly by until you return. A reef tank is a box of life, and life happens whether we want it to or not.

Simple things like water changes, testing, and physical observation are often all that is needed to maintain success. Testing can help determine when water changes are necessary, and help prevent parameters from deviating.

Final Thoughts
How complex or easy the reef tank can be is entirely up to you, and there is
no “one size fits all” scenario. With some patience and research, finding a suitable path is achievable. Filtering out anecdotes and superstition will be a little
challenging at first. I suggest finding someone with a tank that you want to emulate, and ask them how they did it. Success can be had to those that try hard enough! I wish you a happy and successful reefing journey!

-Reefer Matt
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Reefer Matt
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