Your First Reef aquarium: How to Create a 
Miniature Coral Reef System at Home. 
by J. Charles Delbeek B.Sc., B.Ed., M.Sc.

Nothing holds the attention of visitors to a marine aquarium store
more than the sight of a healthy, completely stocked, miniature reef 
aquarium. The variety of colours, shapes and odd looking creatures is 
both bewildering and intoxicating. The gentle swaying of the coral 
polyps, the sparkling of light on the rocks and the darting of the 
fish in and out of the rock work, like so many butterflies in a field 
of flowers, can quickly entice the novice aquarist to purchase such a 
system. Yet, there is much more than meets the eye to these systems, 
and unless one is prepared, you can quickly become discouraged, and 
drop out of this branch of the hobby. Unfortunately this does not 
happen before hundreds, if not thousands, of dollars have been spent, 
and even more unfortunate, before dozens of animals have died. The 
secrets to having a successful reef aquarium include, having patience, 
gaining knowledge, exercising caution, reading everything, and 
practicing common sense. I also believe very strongly that you should 
not follow the advice of someone unless you can see what they 
themselves have accomplished using those methods. If you follow 
someone's advice you will most likely end up with what they have, so 
it would be a good idea to see if that is really what you would like 
your tank to look like. 

There are so many factors to consider when setting up a reef tank that 
it is impossible to cover everything in a single article. Therefore I 
have provided a list of references at the end of this article that I 
encourage you to read as much of as possible BEFORE you start your 
aquarium. It often strikes me as strange that although most rational 
people will spend weeks researching and reading everything they can 
about a major purchase such as a car, these same people can turn 
around and hand over $5000 to purchase a reef aquarium setup, knowing 
very little about it. In my experience, most aquarists end up spending 
3x as much money as they should have by fixing mistakes they made out 
of ignorance or by purchasing equipment/supplies they later learned 
they could do without. One owes it to the animals that will eventually 
be put into these systems, to learn as much as you can BEFORE you 
begin. Reading everything you can get your hands on will probably 
serve to show you that there are many different ways advocated to keep 
these systems, and you will become quite confused. At this point you 
should seek out knowledgeable people in your area who have reef 
systems and see what they are doing. If there is an aquarium club in 
your area with a marine group, then join it. If there is no aquarium 
club then join the specialty societies listed in many aquarium 
magazines. In the aquarium club I belong to, the most common comment 
made by new members is "I wish I had known about you people before I 
started!". Also, frequent the marine store in your area and get their 
advice. But more importantly, frequenting a marine store will expose 
you to other hobbyists, and it is from these people that you can also 
learn a great deal. Finally, no matter what advice you get, you must 
learn to exercise caution, a healthy dose of skepticism and common 
sense.

Having said all of the above, I would like to say that the methods I 
will cover in this article are based on my own experience, those of 
dozens of others and what I have seen in my travels across North 
America and Europe. I am not saying that this is the only way to do 
it, nor necessarily the best way, but it is what has worked for me and 
many others. If anyone tells you that their way is the best or only 
way to proceed then they are not only fooling you but themselves as 
well. The intent of this article will be to serve as a guide to get you 
started with a 65 gallon aquarium in such a way as to ensure the 
greatest possible chance for success, at a reasonable expense. Once 
you gain experience and confidence, then you can start looking for 
ways to change or improve your system.

1) Aquarium Selection and Placement
The first thing you must decide upon is what type of reef aquarium you 
want to maintain. Do you want to keep mainly soft corals or stony 
corals or are algae more your thing? The types of animals you choose 
to keep will have a great deal of influence on the type of aquarium 
and ancillary equipment you will need to purchase. You must realise 
that beginning a marine reef aquarium is a major commitment. You will 
be keeping animals that come to you directly from the wild. Therefore, 
you must be prepared to do what ever it takes to keep them in the best 
possible health. A reef aquarium is not something you can just set up 
and walk away from. Really good reef aquariums require time and 
nurturing to reach their full potential two or three years down the 
road. As a good friend of mine once wrote, only bad things happen 
quickly in a reef aquarium; good things happen slowly (Paletta, 1992). 
If you are not prepared to make this type of commitment, then this 
branch of the hobby is not for you.

Generally speaking the larger the aquarium, the more forgiving it is 
of mistakes in water quality management. Not to say that aquariums of 
less than 50 gallons cannot be kept, only that one needs to be a 
little more vigilant that's all. A small mistake, such as a stuck 
heater, will have a much greater and quicker effect in a small 
aquarium compared to a larger aquarium. The greatest drawback to large 
aquariums though, is that you have to spend quite a bit of money to 
fill it with animals, perform water changes and it takes longer to 
clean. 

When looking for an aquarium beware the tall, narrow variety often 
available. They present numerous problems such as a poor surface area 
to volume ratio (very important for proper gas exchange), and 
difficulties in decorating and cleaning. An aquarium should at least 
be as deep as it is high. The standard 48"x18"x18" 65 gallon aquarium 
is an ideal size to begin with. It's length easily allows for the use 
of the most commonly available 48" fluorescent and metal halide 
lighting systems, and its depth and height make it easy to decorate 
and maintain. 

Before purchasing an aquarium you should make sure that it fits in 
with the dimensions of the room and that the floor where it will be 
placed can support the weight. Placing a reef aquarium where it will 
receive a few hours of natural daylight is not a problem. In fact, it 
can be quite beneficial to the light loving invertebrates you will be 
keeping. As long as no overheating problems can occur, I see nothing 
wrong with this. The belief that natural sunlight will cause algae 
outbreaks is nonsense in a properly run reef tank. When choosing a 
site for the aquarium, keep in mind the availability of electrical 
outlets and a sink, both of which you will need ready access to.

2) The Basic Requirements
There are five main factors that one must keep in mind when running a 
reef aquarium. If these factors are not met, you will not be very 
successful. They are temperature, water movement, light, nutrient 
limitation and water chemistry.

If the temperature of your system cannot be maintained below 80oF you 
will experience problems sooner or later. The ideal temperature range 
lies between 72oF and 78oF. How you achieve these temperatures is up 
to you but they must be achieved.

Water movement is extremely critical in a reef aquarium. Many of the 
organisms you will be keeping such as corals, cannot move from where 
they are growing. They depend on the water to bring them oxygen and 
nutrients, to take away wastes such as carbon dioxide, to remove 
fouling organisms and to ensure that all the polyps get enough light. 
This water motion can be achieved in many ways but it should not flow 
in a straight line (laminar flow). Best are small eddies and swirling 
masses of water that cause the water to flow in a chaotic manner 
through the aquarium. This is best achieved by having a number of water 
returns and/or powerheads in the aquarium, located such that their 
flows can interact with each other. Water motion is also critical for 
the suspension, and removal of detritus and debris from the aquarium. 
Make sure that you have good turbulence at the water surface too, as 
this greatly aids in gas exchange.

Light is an extremely important component in a reef aquarium. Since 
the majority of the corals we keep possess zooxanthellae (single 
celled, symbiotic dinoflagellates), they must receive both the proper 
intensity and spectrum of light to flourish. More will be said about 
lighting in a moment.

One goal most reef aquarists strive to achieve is that of low nutrient 
levels in the aquarium. Namely nitrate and phosphate (since these are 
easily measured) plus numerous other substances generally classified 
as dissolved organic carbon (DOC), need to be kept at low levels. 
Keeping these under control is often the difference between a 
successful reef aquarium and an algae coated mess. Having said this I 
should also add that no real connection has ever been made between 
nitrate levels and poor coral growth. Levels as high as 40 ppm 
nitrogen as nitrate, have been measured in aquariums with beautiful 
stony coral growths (Sprung, 1992c). However, nitrate can fuel 
undesirable algae growth in some cases and should still be maintained 
as low as possible. The best way to control the levels of these wastes 
is through the use of protein skimming (foam fractionation) and 
activated carbon.

Finally, unless you can maintain proper levels of pH, alkalinity and 
calcium, then you will be restricted in the amount of success you will 
achieve in keeping and growing corals, coralline algae and clams. The 
field of trace elements is an extremely active area at the moment as 
new aquarium additives seem to appear each month. Unfortunately, how 
many of these products are actually the product of any original 
research or longterm testing is open to question. However, this is 
definitely an area where breakthroughs are occurring as more is 
learned about the requirements of corals for certain trace elements.

3) Filtration
There has been much written concerning the filtration required to 
maintain a reef aquarium. Everything from pressurized trickle filters 
to just plain airstones has been advocated by various people over the 
years. Basically, filtration can be classified into three main 
categories: biological, mechanical and chemical. How these three are 
achieved is where all the variety and debate comes in. Some would have 
you believe that you need to purchase several hundreds of dollars 
worth of equipment to keep a successful aquarium. Devices such as 
ozone generators, automatic water change and top-off systems, 
alternating surge controllers, denitrification filters, redox 
controllers and metres, pH metres, CO2 injectors, molecular absorption 
resins and trickle filters have been heavily promoted by many as 
absolute necessities. In my experience, while it is nice to have many 
of these aids, they are not necessary for success. As a corollary, 
having all these things on your aquarium will not guarantee success 
either; if you are a poor aquarist, all the technology in the world 
will not help you cover up that fact. I would much rather you spend 
your money on good quality lighting, a properly designed protein 
skimmer and the highest quality live rock you can afford. When these 
requirements have been met, then you can add other "gadgets" if you so 
desire.

a) Mechanical Filtration
The first component of any filtration system is the method by which 
water is removed from the aquarium. Here there is little argument that 
an overflow of one type or another is the best option. An overflow 
functions to continuously remove the surface layer of water, thereby 
increasing gas exchange and removing surface active pollutants to the 
filtration system. An overflow also maintains a constant level in the 
display aquarium.

The overflow can consist of a commercially available unit that hangs 
on the side of the aquarium and operates on a simple siphon. However, 
many hobbyists still use the drilled tank overflow where a hole is 
drilled either in the bottom or side of the aquarium and an overflow 
box built around the hole. Hang-on-the-back overflows are convenient 
to use and are the quickest way to retrofit an existing aquarium. 
Drawbacks include a low surface area for water flow, breaking of the 
siphon can occur, and one needs to be sure to select a pump whose flow 
rate the siphon can handle. Drilled overflows generally offer greater 
surface area for water extraction and they can not break a siphon. 
Drawbacks include making sure the pump is properly sized, any leaks 
could drain the entire tank, and the difficulty in cleaning some 
designs. 

The mechanical removal of large particulates usually occurs in the 
overflow. For this reason the overflow should be easily and quickly 
accessible so that it can be cleaned on a regular basis. Usually some 
sort of untreated sponge or floss material is used to trap particles 
in the overflow. This prefilter, as it is called, should be cleaned or 
replaced on a regular basis i.e. every 2-3 days.

b) Biological Filtration
Biological filtration refers to the transformation of substances in 
the aquarium by many different species of bacteria. These 
transformations generally result in substances that can be harmful to 
the aquarium inhabitants. Fortunately, these substances are further 
acted upon by other bacteria to produce less harmful substances.  
Toxic by-products of waste such as ammonia, are oxidized by bacteria 
into less toxic nitrite, which is then further oxidized by other 
bacteria into least toxic nitrate.  This nitrate then accumulates in 
the aquarium. This is, in essence, the basis of nitrification in the 
marine aquarium. Nitrate levels are then reduced by water changes, by 
assimilation by other organisms or by other biological processes such 
as denitrification, where yet more specialized bacteria act on the 
nitrate to convert it into nitrogen gas, which is quickly released 
from the water.

How one provides for biological filtration in a reef aquarium has come 
under some interesting discussion lately. Some believe that the modern 
trickle filter is the best way to achieve this while others, including 
myself, feel that in aquariums with live rock, trickle filters are not 
necessary for adequate biological filtration to occur. Trickle filters 
achieve biological filtration by presenting a favourable environment 
for nitrifying bacteria to grow. These bacteria then rapidly convert 
ammonia into nitrate, which is then returned to the aquarium. However, 
trickle filters do not only contain nitrifying bacteria but numerous 
other types that can produce still more ammonia and also phosphate.
For a more in-depth discussion of trickle filters, their construction 
and design, I refer you to Delbeek (1990a).

Live Rock
Live rock consists of the calcium carbonate skeletons of long dead 
corals, or other calcareous organisms. Therefore the name "live rock" 
is really a misnomer as the rock itself is not actually "alive" but it 
does contain a multitude of life both inside and out. Most live rock 
are NOT collected from coral reefs themselves, but from adjacent areas 
known as a "rubble zones". These are areas where natural decay 
processes and storms have deposited large amounts of dead coral 
fragments that have become overgrown with numerous organisms. The vast 
majority of these pieces are eventually eroded with time or buried 
under sediments. These rubble areas are continuously buried, exposed 
and reburied by natural processes such as storms and currents, 
therefore any life on them is transient at best. Collection of live 
rock from reefs may be carried out by unscrupulous individuals and 
should definitely not be encouraged. Do not purchase any live rock 
that has sea fans and/or live stony corals attached, as these were 
probably illegally collected and transported. 

The use of live rock immediately introduces into the aquarium numerous 
algae, bacteria and small invertebrates all of which contribute to the 
overall quality of the aquarium water. Live rock has just as much, if 
not more, surface area for bacteria than a trickle filter. Since live 
rock in the aquarium contains various types of bacteria, algae and 
corals, waste products such as ammonia, nitrate and phosphate can have 
a number of fates. Ammonia, nitrate and phosphate are readily 
assimilated by algae and photosynthetic corals growing on and in the 
rock. Ammonia can also be quickly converted into nitrate by the 
bacteria on and in the rock. This nitrate can be either absorbed by 
the algae and corals, or it can be denitrified by bacteria in close 
proximity to the nitrate producing bacteria. 

In reef aquariums that are heavily loaded with fish or where 
overfeeding occurs, the production of nitrate may overcome the rock's 
ability to handle it and you will get a build-up of nitrate in the 
system. This is where additional protein skimming (foam fractionation) 
becomes important. For more information on this topic I urge you to 
read Sprung and Delbeek (1990) and Sprung (1992c).

There are various methods employed today in setting up reef systems,
many of which are successful; some more than others though (Sprung and
Delbeek, 1990). However, I feel that the most important ingredient,
the one that will ultimately determine the appearance of the system
and the time taken to achieve that state, is the quality and amount of
live rock used. The reason for this is that it takes time for any 
system to reach a balanced state and the key to achieving this balance 
is the condition of the live rock. The better conditioned the live 
rock, the more stable the system. One method used to improve the 
condition of fresh live rock is to let it sit in a _unlit_, well-
filtered aquarium for at least a month (this is called "seeding" the 
rock). The rock is of course first stripped of all sponges and algae 
that could die-off and pollute the system. After about a month of 
seeding, the rock is placed into the intended reef tank. By seeding 
the rock in this way, any fouling organisms will have died off and the 
rock will have begun to develop significant encrusting red, pink and 
purple coralline algae growths. This rock is then used to build-up the 
basic structure of the reef. Specialized rock such as plant rock or 
anemone rock are not used until much latter, if at all. 

Seeding the rock in this way is not always practical for the hobbyist 
and we are often forced to place freshly collected rock into our 
systems. The removal of potentially fouling organisms becomes even 
more important in this case as the reef tank becomes the seeding tank. 
The amount of time required to seed live rock depends entirely on the 
state the rock is in when it first arrives. In some cases there is 
very little die-off on the rock and the seeding period can be as short 
as a week. In other cases in may take much longer. Seeded rock is also 
commercially available. If live rock is purchased from a collector, 
depending on how long the rock is in transit, then some additional 
seeding time may still be required when it arrives. A complete 
description of the process of setting up a reef tank using seeded and 
unseeded live rock is given in Sprung and Delbeek (1990).

The source of rock is another factor that should be taken into 
consideration. I prefer to use "reef rock", that is, rock that has 
been collected from outer reef areas. These consist basically of 
pieces of coral and coral rock that have been broken off of the reef 
during a storm or through natural decay processes, and have fallen to 
the bottom, where they are then covered by numerous encrusting 
organisms such as sponges and coralline algae. To my mind this type of 
rock makes the most beautiful and successful reef tank. It also cycles 
very quickly and stabilizes the tank rapidly. Inshore rock tends to be 
denser and is usually covered with numerous growths of macroalgae, 
clams, mussels, crabs, shrimps and other unwanted organisms; in my 
view less desirable. 

Although it is possible to start a reef tank using dead base rock and 
only a veneer of live rock, this takes much longer to mature and the 
possibility of algal outbreaks is much greater. Yet, in some 
aquariums, the dead base rock eventually becomes so encrusted with 
purple coralline algae that it is indistinguishable from live rock. In 
the not too distant future aquacultured live rock will be available 
but it will require long term experience with this type of rock before 
it can be determined how suitable it will be for reef aquariums.

The way the live rock is arranged in the aquarium can also have a 
profound influence on the long term success and maintenance of a reef 
tank. What one sees in many reef aquariums is a haphazard 
conglomeration of rock piled into a brick-like wall, with very little 
regard given to water circulation and detritus build-up and its 
removal. When arranging live rock it is much better to construct a 
loose arrangement of rock, with many overhangs and bridges between the 
rock. Try and couple this with as few contact points between the 
rocks, and between the rocks and the substrate as possible. Do not 
pile the rock up against the back of the aquarium, leave enough space 
behind the rock for water circulation and for detritus removal. Some 
aquarists suspend their live rock above the bottom of the tank with 
sheets of acrylic light diffusor material or feet of acrylic. This 
allows detritus to accumulate below the rock for easy removal by 
siphoning. The same effect, however, can be obtained by the judicious 
placement of live rock.

Of course arranging the rock in such a manner is not easy to do when 
most of the live rock offered for sale are smallish, rounded pieces. 
The ideal shape for this type of arrangement are elongated flattened 
pieces that can be easily arranged to form platforms and bridges. By 
arranging the rock in this manner, organism placement is easier, water 
circulates freely around the rock on _all_ sides and detritus is 
quickly carried away from the rock and collects either in the 
prefilter or on the bottom of the tank where it can be easily removed.

The amount of live rock required in a system is difficult to assess. 
The general rule of thumb is to place the rock such that it takes up 
about 1/3 of the visual volume of the aquarium. Using estimates of 
mass to determine how much rock is required are crude guidelines at 
best. The reason for this is that live rock can vary greatly in 
density. To fill a 65 gallon tank 1/3 full of a dense type of rock may 
require 200 lbs., but if a very low density rock were used only 100 
lbs. may be required.

I cannot stress enough the importance of the quality and placement of 
live rock in having a successful reef tank. Whether you use a trickle 
filter and a skimmer or only skimmers to filter your tank is 
irrelevant, if you have good quality rock with very little die-off, 
this will have a much greater affect on water quality than the 
filtration system. I feel that the importance of the filtering 
capacity of live rock has been greatly down played, and that of some 
filtration systems has been, perhaps, overrated. 

c) Chemical Filtration
Protein Skimmers (Foam Fractionators)
The one piece of equipment I feel you SHOULD purchase is a good 
quality protein skimmer (foam fractionator). These devices play an 
extremely important role in maintaining coral reef aquariums. In my 
opinion, a protein skimmer is an indispensable piece of equipment 
for the marine aquarium, doubly so in a reef system. Foam 
fractionators have been in use in European aquariums for years and are 
often the sole form of filtration used. Obviously this cannot be 
achieved with the smaller, internal skimmers sold for years in North 
America, but by larger, external models. Such models are now commonly 
available in North America, the majority being North American built. 

Protein skimmers consist of a column through which a very fine mixture 
of air and water is pumped. If any of you have been to the beach you 
may recall seeing foam along the shoreline. This foam is produced by 
the action of the waves which combine air, water and certain surface 
active organics to form a stable foam. A protein skimmer works in a 
similar manner. By collecting the foam, proteins and other nitrogen 
containing organics are removed before they are metabolized into 
nitrogenous compounds such as ammonia and nitrate, which is very 
beneficial to the health and maintenance of the system. Therefore 
there is nothing artificial or unnatural about protein skimming, it is 
merely the extension of a naturally occurring process. Of the various 
chemical filtration methods available, only protein skimming 
completely removes most organics before they begin to decompose (Moe, 
1989). The list of substances removed by skimming includes, amino 
acids, protein, metals such as copper and zinc complexed with the 
proteins, fats, carbohydrates, phosphate, iodide, fatty acids and 
phenols. 

Skimmers come in two popular designs, counter-current airstone driven 
and Venturi driven. A Venturi skimmer uses a strong water pump 
combined with a small air inlet to create a suction that forms a fine 
mixture of air and water in the skimmer. Such devices are more 
powerful and require less maintenance than the standard wooden 
airstone driven models; they can also be made smaller. Small Venturi 
models are more selective in what substances they will remove than 
counter-current designed airstone driven models. Counter-current 
models have an airstone at the bottom of the tube and the water flows 
from the top of the tube to the bottom. One of the drawbacks of these 
units is that they require frequent maintenance. In my opinion 
airstone models work quite well and remove a much thicker, darker 
green/brown sludge. There is no real need to purchase a more expensive 
Venturi design unless there are other considerations such as available 
space, that need to be met. The important thing to remember is that 
you cannot overskim an aquarium. For example the above mentioned 65 
gallon could be easily run on a single 2 ft. tall, 4 in. diameter 
counter-current skimmer but adding another one would do no harm. For 
more information on protein skimmers, and instructions on how to build 
your own refer to Dyer and Delbeek (1991).

Bearing the above in mind, a reef aquarium can operate beautifully 
with or without a trickle filter but there are many variables that can 
affect the level of success achieved. Above all, limiting the sources 
and storage zones for nutrients is a general means of keeping the 
system operating properly whether a trickle filter is used or not. One 
can see, for instance, how important a piece of equipment a protein 
skimmer really is as a complement to the trickle filter. In removing 
nitrogen rich compounds before they are broken down, the protein 
skimmer lowers the trickle filter's potential production of nitrate. 
It's value is not lost in systems without a trickle filter either. 
This is also why most hobbyists running their aquaria with skimmers 
only, consider them an essential element for long term water quality 
(Sprung and Delbeek, 1990).

[Continued in part 2]