General Lighting
   Several years ago there was a lot of talk about whether metal halide or Very High Output (VHO) fluorescent lighting was better for a reef aquarium. Having tried both types and having good results with either, we have decided that either type can give excellent results if set up and maintained properly. A general rule of thumb is to provide 5 watts per gallon of aquarium water of either fluorescent or metal halide lighting. This is adequate for corals that need high light intensity and is more than enough for those that don't. The metal halides concentrate heat in a smaller area, so if temperature is a problem, and you don't want to buy a chiller, VHO might be a better choice.

   Generally if you decide to use metal halide bulbs, the higher degree bulbs are better for the control of undesirable algae and the promotion of coral growth. 10,000K and even 20,000K bulbs are now available. The number "10,000K" refers to the temperature color equivalent i.e. 10,000K (10,000 degrees Kelvin) means the color output of the bulb is equivalent to a 10,000 degree sun (actually a 10,000 degree blackbody). The higher the temperature, the bluer the color of the bulb. When only 5500K metal halide bulbs were available, actinic (blue) fluorescent bulbs were often used as a supplement. Since water filters out red light, as you go deeper into the ocean the light gets bluer and so higher temperature bulbs simulate deeper ocean depths. You can actually simulate a deep reef without the high intensity bulbs by using regular 10 watt per foot actinic lighting. ("Actinic" lights are blue.)

   The VHO fluorescent bulbs put out almost 3 times as much light (110 watts for a 4 foot bulb) as conventional fluorescent bulbs. Common VHO bulb colors are full spectrum (sunlight), actinic (blue), and half actinic, half full spectrum. It is generally recommended to use 1/2 to 3/4 actinic to full spectrum bulbs. Recently, the percentage of blue to full spectrum bulbs recommended has been going up. The bulbs will tend to turn red as they are used anyway, so it may be a good idea to go a little heavy on the blue when they are new.

Temperature
   The temperature in a reef system must be maintained in a range from about 72 to 80 degrees Fahrenheit. Usually this means 76-78 degrees with minor daily and seasonal fluctuations. The water temperature in the tropics is fairly stable so you should mimic this as much as possible. If the temperature creeps up in the summer you may consider buying a 'chiller' to keep it cool. Other ways of cooling it are to open the top of the aquarium to encourage evaporation and use a small fan inside the hood to remove heat from the lamps. With the extra evaporation, make sure and replace the lost water with fresh filtered water on a regular basis. Almost all aquariums will require a heater to maintain temperature in the winter. Buy a good thermostatically controlled heater with output capacity of about 1 to 3 watts per gallon for your reef..

Water Movement
   Water movement is important in a reef environment for several reasons. Many of the corals and anemones are filter feeders, which means they get some or all of their nutrients from the water column. Currents also carry away wastes produced by these animals. Detritus should not be allowed to accumulate on the rock and substrate, another good reason for water currents.

   There are many different ways of simulating the water movement in an ocean environment. Some of the more interesting simulate the "surge" of water in a natural environment by pumping water to an overhead storage tank and then periodically "dumping" it back into the tank. Powerheads can also be put on timers so that varying currents can be achieved. At the very least you should have at least one good (400 gal/hr) powerhead in aquariums less than 60 gallons, and two or more in 60 gallon or larger tanks.

For a general discussion of different filtration methods, see: Marine Filtration.

Live Rock and Live Sand:
Almost every reef setup is characterised by the use of live rock and live sand as the main biological filtration method. Live rock is collected directly from reefs and consists of the coral skeletons of "reef rubble" or is cultured from aged rock placed in "farms" near existing coral reef habitats. Live rock gives the added bonus of having de-nitrifying bacteria deep inside the rock to help remove nitrates. Live sand is collected from coral reef bottoms and carries many of the beneficial organisms that live in the reef substrate. Occasionally you may pick up an undesireable species, but the benefit far outweighs any disadvantage when it comes to using live rock and live sand. At least 2 inches of live sand should be used if used exclusively for the biological filter, live rock at 1.5 to 2.0 lbs. per gallon of water is usually recommended.

Conventional High Tech Filtration
  The first efforts at reef keeping involved using the trickle filter for biological filtration along with many high-tech add-on items to control almost every aspect of the water chemistry. Ozone is used to control the redox potential, carbon dioxide is used to provide suitable conditions for macro-algae (with some Ph control), resins are used to target specific chemicals (nitrates, phosphates) and many different additives are used.
   The complexities of these systems is beyond the scope of this treatise and so I will site references for further study to the interested reader. Reference (5) and reference (6) are both good volumes to read concerning the 'high tech' approach. Martin Moe's excellent books, reference (1) and (7) also go into some detail about this approach.

Berlin Method
   Given the high complexity (not to mention cost!) of the conventional approach, several more natural and less expensive approaches have been tried with success. The Berlin method in general relies on live rock for biological filtration and some denitrification, and a large foam fractionator, or protein skimmer, for nitrate control. The protein skimmer will also remove many of the 'beneficial' elements so you really need to perform regular additions of strontium, iodine and trace elements in a Berlin method reef. There are no commonly available tests for iodine and trace elements, so the health of the animals must be used to monitor them.
   A Note of Caution: In our experience additives of any kind can spur the growth of undesirable algae if done to excess. Don't put anything in the tank if you don't know what is in it, and don't exceed the manufacturers' dosage. In general you can get by with a lot less than what is recommended. Of course the best way is to monitor the levels of these elements and only supplement them if necessary.

Examples of Reef Aquarium Supplements from Amazon.com
Reef Iodine Supplement The Berlin Method using heavy protein skimming will require regular iodine supplementation. Some of the organisms that benefit from iodine are leather corals, corallimorphs, and tridacna clams.	Reef Strontium Supplement Strontium supplements are required by certain corals, especially the Small Polyped Stony (SPS) corals in the families Acroporidae, Merulinidae, Milleporidae, and Pocilliporidae. See SPS Corals	Reef Trace Element Supplement Trace elements are another group of chemicals removed by protein skimming. As skimming is becoming more common in all marine aquariums, all of these supplementations are becoming more common.

Dr. Jaubert's Method
    Dr. Jaubert's method is even more 'natural' than the Berlin method since it doesn't use a protein skimmer but instead relies on a deep plenum in the substrate with low oxygen levels to carry out the de-nitrification process. As described in the Fall 1993 and Summer 1994 issue of Aquarium Systems publication of SeaScope, to implement the Jaubert method place a grid 1 inch above the bottom of the aquarium with a 1 mm mesh screen on top. Above this place 2 inches of coarse calcareous gravel, followed by another screen and two more inches of sand on top of that. Pile live rock in walls rather than pyramids to leave as much of the bottom sand exposed as possible to perform the water filtration. What happens is that water in the lower levels has been depleted of oxygen so the de-nitrification along with bacterial reduction of other dissolved organics takes place there. Unlike the Berlin method, this process will not deplete trace elements. So additions of trace elements is reduced or removed. It was stated that Dr. Jaubert did 5% water changes per month on his systems.
   It should be noted that all of these systems it is beneficial to use "live sand" to introduce the bacteria, worms, and other filtering organisms found in natural ocean systems.

Algal Turf Method
  The 'algal turf' method came about through the idea that plants and algae effectively remove nutrients, especially nitrate, and can be grown in a filter area separate from the aquarium. Bright lights are usually used 24 hours per day in the filter area to stimulate algae growth. The algae is then harvested regularly to remove the nutrients that they assimilate to grow. This method also will remove heavy metals and trace elements so additives, to replace trace elements, may be needed. This type of system also demands an external sump and/or filter area, so pumps are necessary. According to Julian Sprung and J. Charles Delbeek in The Reef Aquarium - Volume One algal turf methods may encourage the growth of algae in the main tank area just by the fact of there being a lot of algae in the system. Recently, the "refugium" has become popular, which encourages the growth of plants in a separate tank in the same system as the reef display. This is a natural approach to water maintenance using processes found in nature and works well in maintaining water quality.

   Choosing corals, invertebrates, and fish for the aquarium is the fun part of reef keeping. It is also the most critical for survival of your pets! A great book for an introduction to the complexities of keeping reef fish and corals together is The Conscientious Marine Aquarist, by Robert Fenner. In general the best advice is to make sure the animals you are buying are compatible. For instance, the reef is not a good place for many butterfly fish since they may dine on your corals. Many triggers find crustaceans a handy mid-afternoon snack. Reefs, while allowing you to keep many more corals and invertebrates, are more restrictive on which fish you can keep so be sure you know what they eat and what they are compatible with, before buying any fish.
   Corals can also be chosen for their compatibility and grouped in different ways as may be found in nature such as shallow water (bright white light), or deep water (less intense, blue light) reefs. Another example is a higher nutrient reef with more leather corals, which is common in areas where rivers flow into the ocean, as compared to a low nutrient reef with more hard coral species that tolerate low nutrient conditions.

   There has been a lot written about maintenance in a reef tank. Of course the different filtration methods require slightly different maintenance but in general there are certain guidelines which can be followed for any reef. I am going to break the maintenance into daily, weekly, monthly and yearly tasks as I have seen done in many other texts.

Daily:
   Check for deceased animals and remove them. Notice any leaks or other obvious problems with the aquarium or the plumbing. Also observe the health of the inhabitants and note any sudden changes in coloration or behavior. This can be an early warning sign of impending problems. Also provide top-off water (replace water that has evaporated) if the aquarium is smaller and/or once a week is not often enough due to large water loss.

Weekly:
   Check all chemical levels and adjust if necessary. These should include: salt, calcium, carbonate hardness, strontium, iodine. Also check for nitrates and phosphates and note any changes. Water changes of 2-5 percent can be done weekly. If you have a protein skimmer, this should be cleaned and serviced.

Monthly:
   Change any carbon or other resins (nitrate or phosphate removers). If not done weekly, water changes of 5-20 percent can be done monthly.

Twice Yearly :
   Change light bulbs. If you are using fluorescent, change them gradually one at a time to increase the light intensity slowly over a week or two period. With metal halide, you can raise the lights after changing the bulbs and gradually lower them over the course of the year.

Hair Algae (The Dreaded)
   Hair algae is probably the most common problem encountered in reef keeping. If left unchecked, it will eventually cover everything in the aquarium, and can even choke out corals. Since algae, like most plants, uses nitrates as food, it is generally believed that the culprit is high nitrates along with high phosphates and other dissolved organic nutrients. The usual remedies fall under categories:

1. Reduce nitrates - by increasing protein skimming. reducing or eliminating feeding, increased frequency of water changes and increased amount of water changed. Nitrate removing resins can also be placed in a filter where aquarium water will flow through the resin..   2. Reduce phosphates - Absolutely use filtered water: either R/O or de-ionized, (but NOT distilled) water for your top off water! Do not use distilled water since it may kill an entire reef. Because distilled water has lost all of its minerals and anything else it might have, the water molecules will bond with the fish/invertebrates that have these minerals that were lost by the water. Put phosphate remover resin in a filter. Reduce or eliminate feeding. Make sure your activated carbon is not leaching phosphate into the aquarium. You can test this by testing the aquarium water for phosphates and then dropping pellets of your activated carbon in the test tube. If it leaves blue trails as it drops to the bottom, it is leaching phosphate and should not be used in the reef!   3. Increase animals that eat algae. Tangs, clownfish, rabbitfish (foxface), some kinds of hermit crabs, like blue spotted red legged hermit crabs (or was that red spotted blue legged?) and many kinds of snails. A coral propagation facility in Idaho http://www.garf.org is a good place to obtain these animals. From personal experience we can say these guys really can do the trick!	Activated Carbon 1.6L
	Ammo-chips 12 oz.
	Nitra-zorb 7.4 oz.
	Phos-zorb 7.4 oz.

Brown Algae (The ever present)
    The brown algae that covers the glass every few days is actually a diatom that requires silicates to live. Therefore if we rid the aquarium of silicates, the brown algae will go away. This is done by using filtered water (R/O, de-ionized, NOT distilled) and by using silicate removing resins.
   Usually what happens is you will get a brown algae bloom in the first few weeks after fist setting up an aquarium. Sometimes it will cycle through fairly rapidly and then disappear within a few weeks or months. More commonly however, it will reduce itself slowly until it reaches equilibrium where you only have to clean the glass once per week.

Red Slime
  The red slime 'algae' is actually a cyanobacteria that grows in sheets that will cover portions of the rocks and substrate. Since they live on dissolved organic compounds, the best prevention is a good protein skimmer. Since they are a bacteria, erythromycin will kill it, and is sold as red slime remover, but I would be very careful putting antibiotics in a reef system. In general you are far better off removing the source of the problem, organic compounds, than a quick cure with antibiotics. Another remedy we have seen used with success is to increase the water flow in areas where red slime grows since it will not tolerate water currents!

1. Martin A. Moe Jr.,  The Marine Aquarium Handbook, 1992
2. Julian Spring and J. Charles Delbeek, The Reef Aquarium - Volumes One and Two, 1994, 1997
3. Helmut Debelius and Hans A. Baensch, Marine Atlas, 1994
4. Dr. P.V. Loiselle and Hans A. Baensch, Marine Aquarist Manual, 1991
5. Albert J. Theil, Advanced Reef Keeping, Aardvark Press, 1989
6. John H. Tullock, The Reef Tank Owner's Manuaol, Aardvark Press, 1992
7. Martin A. Moe Jr.,  Marine Aquarium Reference, Systems and Invertebrates, 1992