I've been keeping marine and freshwater tanks for 33 years, have published articles on marine fish husbandry in both print (Tropical Fish Hobbyist) and online media, (AAOM) and taught
the marine fish husbandry class for Reefs.Org back in it's heyday.
With that out of the way, here's a few pointers.
First, the old "get a bigger tank" narrative is old, outdated advice.
With proper methodology it's actually easier to maintain a 7 or 10 gallon nano tank than a 40, and cheaper to boot. A skimmer is generally waste of time and money on tanks this small since water changes are so easy and quick - the water change is your nutrient export, you don't need a skimmer. Yes you can run one, and on anything over 20 gallons it starts to make more sense.
There are PLENTY of smaller marine fish that do very well in tanks this size. Marine fish can no more be shoehorned into a single category than freshwater fish. I had a 7 gallon nano bow-front on my desk at work for a few years, and all I did was a half gallon water change once a week. No skimmer.
Way below at the bottom of this post, below my article text, you'll see a picture of a 12 gallon reef I had set up for a while, note the Tridacna maxima clam, and this isn't a high light tank either. 32w of flourescent lighting if I remember correctly. NO SKIMMER.
The P. frdimani (purple fish) was brought home eventually from the 7 gallon reef at work.
There are many misconceptions about marine tanks, even by people who've been doing it a little while. The truth is that if a few simple rules are followed, it can be as easy as a freshwater tank.
Here's an article I wrote for TFH some years ago.
It's hardly comprehensive, I had a rather restrictive word limit, so it's just a basic primer.
A freshwater aquarists guide to marine aquariums.
Most of us in the marine hobby started out keeping freshwater fish, often for many years before finally setting up a marine tank. We happily kept to our cichlids, or livebearers, our Blue gouramis and Red Tailed sharks, and let the saltwater people deal with their overpriced hassle of a hobby. Either that or we wanted to keep a marine tank, but were intimidated by all that we heard or perceived of the hobby. “It costs too much money”, or “it’s a lot more maintenance…the fish are expensive… they’re not as hardy”, etc etc. Many of you reading this article can relate to this, and thus perhaps you have not dared venture in the world of marine aquaria yourself.
Let me just say first, that there is nothing wrong with sticking with freshwater. Marine aquariums do not necessarily represent a more advanced level of the hobby, they are not “better”, nor more interesting than a well planned freshwater setup, especially where planted tanks are concerned. The fact is, that while there are a few erroneous contentions about marine tanks, there are also serious considerations that should be taken into account before committing to a marine setup. With that, let’s investigate what the marine hobby will require of you in order to be successful and hopefully you’ll know what questions to ask yourself, and your local fish store should you decide to plunge into this hobby.
First, there is no one single way to set up a marine system, and I could easily write an entire book just on various setups and pros and con’s of each.
The choice of tank, and in particular and the size of this tank is the first budgetary question you must wrestle with. Larger tanks are not only more expensive to purchase initially, but the cost of the live rock, lighting, skimmer, pumps and other equipment go up drastically as the tank size increases. If one is opting for a reef rather than a fish only setup, the cost of fully stocking the tank with various inverts can be truly astounding. For this reason it’s best to do plenty of research, and cost out the various components before laying hard earned cash down on a 200 gallon tank. Such a large tank might seem within your budget, but can you afford the light that will be necessary? What about the skimmer, sump, live rock, and power bill? Can you afford to replace your metal halide bulbs twice a year? Be thorough, and most importantly, be realistic. What is the financial reality for you if, due to an unforeseen disaster, you lose a 200 gallon tank full of inverts? Can you absorb such a loss an continue with the hobby? Can you afford to stock such a tank? Sometimes it’s far more rewarding to have a 12 gallon tank that is full of life and abundant, rather than a huge tank that sparsely populated due to budget constraints.
Chances are you have a few spare tanks lying around, or perhaps you’re thinking of converting a current freshwater display. For a simple fish only setup, you needn’t look any further for your first marine tank; at least as far as the glass (or acrylic) box is concerned. That being said, most marine systems these days make use of a sump below the main tank, which houses a protein skimmer, the heater, supplemental mechanical filtration, and often a refugium (a partitioned, protected area which allows small critters such as copepods to breed, and where macro algae is often grown) as well as adding to the overall volume, and therefore efficiency of the system. This means a drilled tank with overflows must be used, and this cost must be factored in during the planning process. A sump is not absolutely necessary, but highly advisable on a system over 30 or 40 gallons where larger protein skimmers are normally used.
Lately several manufacturers have introduced self-contained setups called “nano cubes”, which range from 6 to 24 gallons. They sport an attractive, tight fitting hood with power compact lighting sufficient for many soft corals, a pump and filter media. The glass on these units is a single curved pane, which wraps around 3 sides of the tank, and is quite attractive. These units make great starter kits for a marine tank, but often they need some modification to make them ideal, such as additional ventilation in the hood to prevent the lights from overheating the tank, more powerful or reliable pumps, and stronger lighting for certain inverts. They are definitely worth a look however if one is considering a small marine setup.
What about lights? Do I need metal halides?
While an in depth discussion of lighting is beyond the scope of this article, some points nevertheless should be made. The first thing you’ll likely wonder is if the lighting from your current freshwater tank will suffice for a marine tank. The answer, if we’re just talking about a simple fish only system, is yes. If the tank is small, and you’re only considering some hardy, lower light soft corals such as mushroom corals and star polyps, then a power compact fixture will be sufficient. Upgrade kits, which contain everything needed to change a normal fluorescent fixture to a power compact fixture can be purchased online and at more specialized local retailers.
If on the other hand you’re thinking of diving into the world of stony corals and giant clams, you’re going to need a light fixture of considerably higher wattage. If you you’re thinking of upgrading your lighting however, this can be one of the most confusing and frustrating aspects of delving into the marine hobby, and the learning curve often involves purchasing the wrong lights first, then figuring out what you should have purchased later, doubling your expense! Do your due diligence, research and talk to other hobbyists before you purchase.
A larger reef full of stony corals, lit by several 400-watt metal halides can be staggeringly expensive to operate, not only in initial cost, but in the power bill department as well. A small tank with a few small power compacts and some soft corals will cost less initially, and have a much smaller effect on your monthly power bill. When more light demanding inverts are involved however, more light is needed, and your choices become myriad when all the various manufacturers and levels of output are considered
The power heads, and maybe even a power filter you have laying around could come in handy to help circulate water in your marine tank, but the actual bio-filtration on your marine tank will be accomplished with live rock, sand, and perhaps a protein skimmer as well. A protein skimmer is highly recommended, especially for tanks over 30 gallons or so. These units removed undesirable organics from the water column and help oxygenate the water, and thus are highly beneficial workhorses in most (not all) successful systems. Wet/Dry filters, much in vogue back in the day have more or less fallen out of favor since they produce nitrates, but lack the denitrification ability that live rock affords. You may choose to put a sump below your tank to house your pumps, heater and protein skimmer. A sump not only keeps these items out of the main display and cuts down on clutter, but adds to the overall water volume of the system, this increasing it’s efficiency.
Saltwater tanks difficult to maintain, and are a lot more work!
I can’t tell you how many times I’ve heard this over the years, and it’s simply most often not the case. As a matter of fact, a properly set up marine tank often requires less maintenance than a freshwater system of the same size. This isn’t to say that every marine tank falls into this category, but it’s hardly a foregone conclusion. The live rock and sand beds that we use in a modern marine system enable most sensibly stocked tanks to go a full month or more between modest water changes, and the water changes can often be much smaller than in most freshwater systems. This is because in a freshwater system the bio-filter sustains nitrifying bacteria, which convert nitrite in nitrates via the nitrification process. The nitrate is removed via water changes before it reaches toxic levels. We must do these water changes (often on a large scale) to keep nitrates in check. In a marine system, our live rock goes a step further and converts the nitrates into nitrogen gas via the denitrification process. This gas leaches harmlessly out of the system on it’s own with no interference from the aquarist. This means that a marine system is comes much closer to a self-contained, self-regulating system than our familiar freshwater tanks. Water changes are our main tool for controlling nitrate in a freshwater system – not so with a marine system. In short, a freshwater tank requires more work to eliminate toxins from the water than a marine tank.
Various parameters need to be monitored in a marine system, but even a 120 gallon full of stony corals will only require a few minutes a day to keep things in check. Water changes must be carried out regularly, but as stated above this happens with less frequency, and the percentage of the change is smaller. Protein skimmers need to be cleaned now and then, but so does a canister filter, under gravel filter or power filter on a freshwater tank. Larger tanks take longer to maintain, just as with freshwater aquaria, and while a marine tank may average a few extra minutes a day, the difference is hardly jaw dropping. To this day the most maintenance intensive tank I’ve owned was a 180 gallon freshwater tank full of large central American cichlids. No marine tank, even those in the same size range has come close.
The Fish are much more fragile
Well, they can be if you’re a glutton for punishment and pick fragile fish! The fact is that there are many hardy, long-lived marine species available at your local fish store. This isn’t to say that you can throw quarantine procedure out the window; practicing proper quarantine technique is essential to your success as a marine aquarist. What it means is that when sensible husbandry practices are employed, and hardy species are selected, there’s no reason why you can’t experience the same success as a beginning marine aquarist as you’ve grown accustomed to as an experienced freshwater keeper. There are many references available to help you select hardy species, including Scott W. Michael’s excellent work, which you can find at many books retailers and fish stores. The long and short of it is, you’ll find many species of fish for sale that are hardy and likely to thrive, and plenty that rarely adapt to captivity and should be left in the ocean! You’ll need help avoiding these species, and picking those that are best suited to the small piece of ocean that your considering.
The mistake many beginning marine aquarists make (and frankly, many of the more advanced ones as well) is becoming smitten with a beautiful fish and making an impulse purchase without researching the suitability of that particular fish to captivity in general, or perhaps just to the experience level of the aquarist himself. This is easy to do, and many Powder Blue surgeonfish and Mandarin dragonets have been purchased and subsequently lost as a result. This is not only unfair to the fish themselves, but the confidence of the aquarist often suffers as well, frustration ensues, and an opinion is formed about the difficulty of the marine hobby that often persists indefinitely. This is unfortunate, and totally avoidable. Indeed, there are plenty of marine species that one would nearly have to hang on a clothesline to kill! So why waste energy, time and money on the species that are chronically difficult or impossible? Your guess is as good as mine, but those hobbyists (and ex hobbyists) are numerous and easy to find.
Invertebrates are difficult to keep and expensive
They can be both, but need be neither. Just as with the fish, there are many species of invertebrates offered in stores or online that should be left in the ocean, and just as in selecting fish, research and restraint while making purchases go a long way toward success in invertebrate husbandry. Some corals are hardy and undemanding; many others do very well but require expensive lights, multiple costly pumps to provide necessary water movement, and an experienced keeper. Some corals are simply fragile and rarely do well in home aquariums. Green Star polyps and mushroom corals are examples of corals that are extremely easy to maintain, and provide a nice, confidence building foot in the door for budding reef aquarists.
Marine tanks are more expensive.
This one I’m afraid I cannot refute. Marine tanks are definitely more expensive, and that cost, and the potential scale of financial loss should something go wrong can reach absolutely insane proportions as the size of the tank increases. A member on some reef aquarium board or another once had a signature that read “my sanity, as well as my wallet lay at the bottom of my reef tank.” While cause for a chuckle, this can become more of a reality that we’d like to think. With so many variations in livestock, equipment and methodology, it’s impossible for me to make a blanket statement with regard to how much more expensive a marine aquarium is. The cost difference can range from a few extra dollars a month for a small or simple setup, to many thousands of dollars extra when initial setup costs and month expenses are considered. The most important considerations are the size of the tank, and whether your setup will be fish only, or one of the many possible reef variations. Each requires different equipment, time investment, and upkeep costs. You often have a sump to consider which is absent from most freshwater setups, a protein skimmer which gets larger and more expensive as the size of the tank increases, extra pumps to provide proper circulation for corals that again get larger and/or more numerous as tank size increases. Live rock is heavy, and sold by the pound, and lighting can run from under a hundred, to many thousands of dollars depending on the size of the tank and light intensity required for the invertebrates being kept.
When reefs are considered, the amount of livestock it takes to create a full, abundant look is drastically different between a 20-gallon and a 200-gallon tank. It’s literally the difference between shelling out $300 vs $3000 or more in initial cost. The monthly upkeep cost also increases significantly, depending on the size of the system and the needs of the organisms within that system. A reef tank with multiple pumps running 24/7, a metal halide fixture, and sometimes a chiller to keep things from overheating in the summer can drastically increase your power bill, we’re talking hundreds of dollars, so be warned! Can you realistically afford the initial cost of the tank you are considering? Can you afford the monthly power bill, the salt mix for the water changes, and the cost of replacing expensive metal halide bulbs every 6 months? If you live in a hot climate, a chiller might be a must, adding significant initial and monthly costs.
Is your living situation stable? Moving a large aquarium of any type is exhausting work, put possible if some planning takes place. If your move means the tank must go, then you will never recover your initial investment in the setup, think live rock, equipment, and animals. Tanks, live rock and critters can be sold through a classified ad, but be prepared to take a soaking! The magnitude of this loss of course increases with the size of the tank.
Bigger is better
That’s old school thinking, and simply not always the case. If you’re thinking of converting your current 30-gallon freshwater tank into a marine display, go for it! Or go as large as your time, space, funds allow. By far the most trouble free and enjoyable tanks I’ve ever maintained were several small “nano” tanks. One of these was a 7-gallon nano reef on my desk at work, and the other a 12-gallon nano reef system at home. The reasons? Well to begin with the small size of the tanks meant that a skimmer wasn’t required. This meant less noise, less money, less space, and less upkeep. Water changes on a small tank are so easy, and so quick, that it makes a skimmer superfluous. Filtration was accomplished simply by a few pounds of live rock, and a small power filter with the filter media removed which provided just the right amount of circulation in the tank. A gallon or two of water siphoned out once a week, a gallon of water back in…2 minutes later my weekly maintenance is finished. Once a day I dragged the small magnetic cleaner across the glass, a 20 second operation that more or less wrapped up my daily maintenance. A tight fitting top meant evaporation was minimal, with fresh water needing to be added every few days, taking a whopping 15 seconds or so. A few hardy soft corals, a few shrimp and a singly hard Orchid dottyback lived in this tank for several years. A small upgrade in the light fixture was all that was needed to keep the hardy corals in this tank. I worked 4-day weeks, and the tank was no worse for wear after being ignored over 3 day weekends.
The point here is that a small, well-stocked and healthy system that isn’t a cause of financial stress is much more desirable, enjoyable and impressive than a large, sparsely populated, poorly maintained money pit. A smaller tank also represents a much smaller risk should disaster strike (much less likely with smaller, simpler setups) or when a move forces a hiatus from the hobby. Be realistic with yourself, and choose wisely!
A marine tank, especially a more complex reef setup is far more vulnerable to mishap while you take a vacation (Murphy’s law just loves vacations) than a freshwater setup, which is generally more bullet proof. This is because of the multiple pumps that are often present, the protein skimmer, calcium reactor, chiller, very hot running lights and more complex plumbing often employed, along with the delicate nature of the animals that many aquarists choose to keep. The more complex the system, and the more specialized the needs of the organisms within, the more you’ll be loath to leave the tank for very long…be warned!
Lessons learned keeping a freshwater system will server you well in the marine hobby. There are complexities beyond that of freshwater aquaria, but simple systems are possible and just as rewarding. If you research the animals thoroughly before you purchase; choose animals that are well suited to captivity, and are realistic about your immediate and long term budget, you should have no trouble making the transition into salt water aquaria.
12 Gallon nano - no skimmer, extra live rock in filter compartment.
3 gallon or so water change very week. Easy peasy.