How to Set up a Marine Reef Aquarium

Setting up a marine reef aquarium may seem like a daunting task, but is fairly easily achievable provided you follow a few steps.


  1. Image titled Select the spot for your aquarium Step 1
    Select the area of the house where you want the tank to be. Put the tank in a area of the house which isn't drafty, near a radiator, near a window, in direct sunlight, or near other sources of fluctuating temperatures, for example kitchen areas . Also avoid areas which can get overly hot or very cold. Don't put it in a very busy area, but make sure you can see it enough to enjoy it!
  2. Image titled Buy the largest aquarium that will fit in your space and your budget Step 2
    Buy the largest aquarium that will fit in your space, or the largest aquarium your budget will allow. Larger aquariums provide a much more stable environment, because the water chemistry will be easier to maintain over time.
  3. Image titled 500px Choose between acrylic or glass Step 3.png
    Choose between acrylic or glass. Acrylic will scratch easily but is easier to drill and is much lighter. You can buy a tank pre-drilled, or if you are handy do it yourself (using a diamond bit hole saw). Some fish shops and glass stores will also provide this service. A tank with an "internal overflow" is a big plus. These are often sold as "reef ready". It is better to choose a tank that is not too deep(e.g. 24 to 30") so you can reach the bottom easily; a tank that is wider will provide a better depth of view for a more natural look as well as have better light penetration. A second smaller tank (a sump) is placed under the reef ready aquarium and will hold all the equipment out of sight. A sump is not a need per se, but it is nice to be able to hide equipment in as well as increasing the overall water volume in your system.
  4. Image titled Choose your lighting Step 4
    Choose your lighting: Metal halide lamps provide the best lighting for most of the corals commonly kept, other forms of lighting are also obtainable and offer varying degrees of success. 250 watts bulbs will suit most common aquariums except for the deeper ones where 400 w bulbs provide more light penetration.The color spectrum of the bulbs (expressed in color temperature in Kelvins) is a matter of personal preference. Bulbs between 10,000 kelvin and 20,000 kelvin are the most popular, and the higher the kelvin rating the 'bluer' the color. Some claim coral growth is affected by the color, but corals grow fast and successfully on either end of the 'spectrum'. One halide bulb for every 2–3 feet (0.6–0.9 m) of tank length is usually recommended.
  5. Image titled Other types of lights to consider are florescent lighting Step 5
    Other types of lights to consider are fluorescent lighting, specifically high intensity fluorescents. Two popular kinds are Power Compact and T5, or T5HO (meaning T5 high output). These can be found in many of the same color ratings as metal halide bulbs, and are often cheaper and produce less heat than a metal halide. A popular choice is to use both fluorescent and metal halide. The main thing to keep in mind when choosing a fluorescent T5 fixture is to make sure to buy one with individual reflectors. While the lights do put out a fair amount of light with regular parabolic reflectors, they become amazingly bright using individual reflectors. Many people choose to use a single color of metal halide, like 10000k, and will use a few blue (or Actinic) fluorescents to make the color more pleasing.
  6. Image titled Set up the filtration Step 6
    Set up the filtration: On a smaller tank (less than 40 gallons) regular weekly water changes can be used in place of a skimmer. If you have chosen to buy a larger tank (40+ gallons) a protein skimmer is a very important piece of equipment to purchase. Get a good quality protein skimmer and place it in your sump or on the back of your tank if it is designed for it. Do not skimp on this. Often protein skimmers are under-rated for the size of tank, so in practice a skimmer rated for a 100 gallon (378.5 L) tank is barely adequate for a 50 gallon (189.3 L) reef tank (especially one with many fish that get fed a lot). Needle wheel skimmers are a popular choice, and can be very effective for their size/cost. Don't rely on 'venturi' skimmers, unless they are high end models with very strong pumps. Don't bother buying 'canister' filters, often used on freshwater aquariums. Not only are they fairly useless in a marine aquarium environment, they can cause a buildup of Nitrates on their internal media that can negatively effect the aquarium. That being said, a canister filter can be used for carbon or other chemical media, provided it is cleaned on a regular basis.
    • A skimmer quickly becomes cheaper than salt-water changes.
    • If the aquarium is not heavily stocked and does not have delicate (or very valuable) fish, try putting the skimmer and even the filter on a timer--though there must always be some circulation such as from powerheads--to allow everything to filter-feed during the day and have its water cleaned thoroughly at night.
  7. Image titled Adjust the flow Step 7
    Adjust the flow: Now is time to get a saltwater rated pump to return the water from your sump to the main tank. Additional powerhead pumps in the tank or external pump(s) should be installed to provide additional vigorous turbulent flow to otherwise stagnant areas, which is crucial to the survival of your future corals.
  8. Image titled Place a heater(s) in your sump, or the rear chambers of your tank Step 8
    Place a heater(s) in your sump, or the rear chambers of your tank.
  9. Image titled Consider using an aquarium chiller Step 9
    Consider using an aquarium chiller. The high intensity lighting used in reef aquariums adds a surprising amount of heat to the aquarium, making it harder to keep a reef aquarium 'cool' enough. Although heat issues are not as much of a problem in cooler countries like Canada, you'd be surprised just how much the heat can creep up on a warm day in your tank. The point is to try to keep the temperature variation minimal. The less your temp. varies throughout the day and night, the more stable your marine environment will be.
  10. Image titled Fill the tank with tap water partially to test for leaks Step 10
    Fill the tank with tap water partially to test for leaks. Run all your pumps. Turn the sump pump off to see how much water drains into it. Use a piece of tape to mark your "maximum" water line. That is the maximum amount of water that can be in your sump before it overflows. You can also put a piece of tape down for the minimum fill line, which is the minimum amount of water required in your sump to get the pump to work and not blow air into your display. Run the water level somewhere between those two lines. The chamber housing your pump is usually the one in which you will notice a drop in the water level due to evaporation. There are auto top off kits available to top your water off daily with fresh dechlorinated water(no salt). Alternatively, you can top off manually by marking where you want your water level to be and then keeping it full to that line with fresh dechlorinated water (preferably RO/DI).
  11. Image titled Prepare enough artificial seawater for the volume needed and add sand Step 11
    Prepare enough artificial seawater for the volume needed. Use only a good aquarium sea salt brand and purified water with a Reverse Osmosis or R0/DeIonization Filter. Another option is to fill the tank with RO/DI water and then add the salt. The importance of RO/DI system cannot be understated. Tap water can be used, but your aquarium is then at the mercy of whatever harmful chemicals may be in it. A good RO/DI system is not too expensive, and should be considered a necessity. A 100 gallon (378.5 L) per day model is a good choice, because you won't have to wait too long to make purified water which is a nice convenience. If your tank is smaller you can purchase bottled RO water at your local store. Use of distilled water is not recommended as most distillation units use copper pipes. Copper is toxic to most invertebrates; including corals, decorative shrimp, etc.
  12. Image titled Let the water 'rest' for a day Step 12
    Once you mix your saltwater and fill your aquarium, turn on all your pumps and let the water 'rest' for a day. It takes a little time for your salt to dissolve and your water chemistry to stabilize, and the action of the pumps will drive out excess carbon dioxide (which initially causes a low pH). You can add sand if you choose to, either before adding your water (if it is not a live bed) or after. If it is a "live" sand bed, add it after you have mixed your saltwater in the tank. Leave the skimmer off until the sand settles. A sand depth of 4 to 5" is recommended for maximal detritus biological processing (at this depth only seasoned hobbyists as at 4 to 5 inches many nasty things can grow as well -research aerobic and anaerobic sand beds for reef tanks).. Some folks prefer the look of the sand bed, but don't want the possible "old tank syndrome" that can come with having a deep sand bed. (Old tank syndrome happens when the sand bed has accumulated more detritus than it can handle and may result in a "tank crash" if pockets of toxic H2S are stirred up in the bed.) A 1-2" sand bed can also be used as long as the detritus is vacuumed out on a regular basis ( this is actually the preferred depth, especially for beginners).
  13. Image titled Another way to go is not to add sand at all Step 13
    Another way to go is not to add sand at all. This is called "bare bottom". It is much easier to keep the tank clean with a bare bottom, as you can easily siphon out the detritus. It's not as pleasing to the eye perhaps, but for many people, the ease of keeping it clean makes up for that fact.
  14. Image titled Add 'live rock' Step 14
    Add 'live rock' and arrange to your liking, approximately 20% of your volume. The rock can be placed on an aragonite sand bed, or alternatively you can add the rock prior to the sand. Live rock can be obtained online, from other hobbyists or at your local marine aquarium store.
  15. Image titled Let the tank cycle Step 15
    Let the tank "cycle": This means you will need to wait until the water tests negative for ammonia and nitrite. Inserting bits of frozen fish foods in the sand bed can speed the cycle. (This is unnecessary if you added live rock. There are plenty of dead crustaceans and worms already inside due to shipping). This may take 1 to 6 weeks. Algae blooms can be a natural part of the cycle. Check and make sure the salinity is stable at 1.023 to 1.026. This does not mean it can be 1.023 one day and 1.026 the next. Find the salinity you want and keep it at that level. 1.025-1.026 is the optimum salinity for corals; a lower salinity is inappropriate for inverts/coral. A fish only tank can be kept at 1.021-1.026. Compensate for evaporated water losses with RO/DI water. Keep the temperature, Calcium and Alkalinity levels stable. Do not use commercial "supplements" other than water changes unless you know what you are doing. Algae blooms are common for probably the first 6 months of your aquarium, so don't be alarmed to find new algae growing. Just keep it clean and do about a 10% water change every week. Once your tank is stable you may choose to slow down the water changes. Ensure the new water has been heated and mixed for a while in a separate container prior to putting it in your tank.
  16. Image titled Add cleaning creatures and fishes Step 16
    Add cleaning creatures such as snails and small hermit crabs, and finally reef fish.
    • If this is your first reef aquarium, get just one to three inexpensive fish that will be compatible with a variety of other fish including any specific exotic kinds you may want later. Being inexpensive means not only that they will not be a big monetary loss if they die, but that they are strong (thus plentiful) and less likely to die. Being few (and small, which tends to go along with inexpensive) means they are unlikely to overload the biological filtration as you start out.
  17. Image titled Corals and anemones will be added until the tank is a few months old Step 17
    Many aquarists feel its not proper to add corals and anemones until the tank is a few months old. A 'mature' tank is much more suitable for growing coral. A good rule of thumb is to watch your live rock. At some point you will notice your rock or your glass developing spots of purple. The purple encrustation you see is called coralline algae. The right conditions for coralline are correspondent with the right conditions for coral. You will seen new crustaceans, worms, feather dusters, coralline and more. Once you see this marker, assuming your test kits still read 0 for ammonia and nitrite, and less than 20ppm for nitrate, you can begin to add coral.
  18. Image titled Join a saltwater aquarium community Step 18
    18 Join a saltwater aquarium community like REEF2REEF and ask a ton of questions and read, read, read!
  19. Image titled Setting up a Marine Reef Aquarium Intro


  • Read books, join online reef keeper boards and ask lots of questions. Buying a refractometer and quality test kits is a good investment.
  • Pump volumes vary per the amount of head space (vertical distance) a pump has to overcome. Check the pump specifications for what the pressure is for the amount of vertical lift will be required. Horizontal distance is not factored as it has minimal impact unless your going a long distance (10' or more).
  • Invest in a refractometer for measuring your salinity accurately. It is a minimal expense around $30.00 and is much easier and more accurate than liquid tests or old school hydrometers.


  • Long term commitment required. Some fish will live more than 20 years with good care. Many corals will outlive their owners.

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Categories: Aquariums