A
reef aquarium or
reef tank is an aquarium
containing live
corals and other animals associated with coral reefs. It
is considered to be one of the most difficult
aquarium setups to create and maintain. In recent years,
advancements in our knowledge of the reef, coupled with more
refined reef maintenance techniques, the reef tank has
become much more accessible to the hobbyist.
From theme
reefs which attempt to recreate life specific to one region
of the world like the
Great Barrier Reef to the more prevalent and often
spectacularly colored mixed reef that blend hard and soft
coral from around the world. Unlike the
marine aquarium which main purpose is to house various
fish, the true stars of the reef tank are the
coral and other
invertebrates.
Methodology
The aquarium
The first step in building a successful reef aquarium is
the tank itself. Most hobbyists prefer what are called "Reef
Ready Aquariums" which are identical to regular glass or
acrylic style tanks save for an internal overflow made of
plastic or glass which encloses holes that have been drilled
into the bottom glass to accommodate a drain or standpipe
and a return line. Water pours over the overflow into and
down the standpipe, through
PVC piping, into a sump, which houses various filtration and
heating equipment, through a return water pump and finally
back via more piping through the second hole into the
aquarium. An alternative method to having a tank that is
already drilled is to use a hang on tank overflow with a
U-tube (via a continuous siphon).
Filtration
Unlike the
marine aquarium that use a combination of mechanical,
chemical and biological filtration, reef aquariums primary
filtration comes from the use of large amounts of
live rock which come from various rubble zones around
existing reefs or more recently aquacultured rock from Florida which is supplemented by
powerful
protein skimmers. This method first came from
Germany and is aptly termed the Berlin Method.
The typical rule of thumb is to use from .75 to 2 pounds
of
live rock per gallon of aquarium water depending on the
density of the rock – or filling the tank up 2/3 of the way
to the top. The benefit of using
live rock is four fold: First, live rock acts as a
biological filter, adding beneficial bacteria. Secondly, it
introduces an abundance of marine life to the aquarium that
many
fish,
invertebrates and corals use for food. Thirdly, it provides
a natural reef appearance with ample places to locate
corals. Live rock also will help balance and stabilize PH in the aquarium.
Mechanical filtration is often avoided because sponge
filters, filter floss and filter socks trap detritus and
produces nitrates which stunt the growth or even kill many
delicate
corals. Chemical filtration is used sparingly so to
avoid discoloration of the water, to remove dissolved matter
(organic or otherwise) and to help stabilize the reef
system.
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Water movement
Corals are simple creatures with limited ability to
feed, reproduce and rid themselves of waste(metabolites).
An example of a closed loop water cirulation
system
Water movement is key to the success of the reef tank
with each type of coral requiring different flow rates. At
present, many hobbyists advocate the 10x rule: 10 x aquarium
capacity in gallons = required flow in gallons per hour.
This is a general rule with many exceptions. For instance,
Mushroom Coral requires little flow while many species
of
Acropora thrive under much more turbulent conditions in
the range of 30 to 40 times more flow most likely due to
their proximity to wave crests in the wild.
Of the many different types of creating this needed water
flow the most popular method is by using multiple
power heads which are simply small submersible
water pumps. The pumps are randomly switched on and off
using a wave timer. Each aimed at the flow of another
power head or at the aquarium glass to create a random
flow in the tank. Another method gaining popularity is the
closed loop by which water is siphoned from the main
tank to a pump that in turn pushes the water right back into
the aquarium via multiple returns to create water
turbulence.
Water flow is important to bring food to corals. No coral
relies 100% on photosynthetic food. Gas exchange occurs as
water flows over a coral, bringing oxygen and removing
gasses. Without water flow corals die. Water flow helps
reduce the risk of thermal shock. Temperature of a corals
surface can be significantly higher due to infrared
radiation in slower water flow. Faster water flow aids in
preventing thermal shock, reducing the temperature of the
corals surface.
Lighting
Another hotly debated topic is
aquarium lighting. With the advent of newer and better
technologies, increasing intensities and a growing spectrum,
the topic of aquarium lighting can be a daunting one even
for the seasoned aquarist.
Many, if not most aquarium
corals contain within their tissue the symbiotic algae
called zooxanthellae. It is these zooxanthellae that require
light to perform photosynthesis and in turn produce simple sugars that
the corals utilize for food. The challenge for the hobbyist
is to provide enough light to allow photosynthesis to
maintain a thriving population of zooxanthellae in a coral
tissue. Though this may seem simple enough, in reality this
can prove to be a very complex task.
Some corals such as the
Mushroom Coral and Coral Polyps require very little light to
thrive – conversely, Acropora Coral, Brain coral, Bubble
Coral, Elegance Coral, Cup Coral, Torch Coral, Trumpet Coral
can require substantially more intensity.
Of the various types, most popular aquarium lighting
comes from
metal halide, very high output or VHO, compact fluorescent
and T5 high output lighting systems. Although they were once
widely used, many reef tank aquarists have abandoned T12 and
T8 fluorescent lamps due to their poor intensity, and
mercury vapor due to its production of a limited light
spectrum.
Recent advances in lighting technology have also made
available a completely new technology for aquarium lighting:
Light Emitting Diodes (LEDs). Although LEDs themselves are
not new, the technology has only recently been adapted to
produce systems with qualities that allow them to be
considered viable alternatives to gas and filament based
aquarium lighting systems. The newness of the technology
does cause them to be relatively expensive, but there are
several advantages that these systems bring over traditional
lighting. Although their initial cost is much higher, they
tend to be economical in the long run because they consume
less power and have far longer lifespans than other systems.
Also, because LED systems are comprised of hundreds of very
small bulbs, their output can be controlled by a
microcomputer to simulate daybreak and sunset. Some systems
also have the ability to use simulate moonlight and the
phases of the moon.
The choices for aquarium lighting are made complicated by
variables such as
color temperature, (measured in kelvins), color rendering
index (CRI), photosynthetically active radiation (PAR) and
lumens. Power output available to the hobbyist can range
from a meager 9 W fluorescent lamp to a blinding 1000 W
metal halide. Lighting systems also vary in the light output
produced by each bulb type--listed in order of weakest to
strongest they would be: T8/12 or normal output lamps,
compact fluorescent and T5 high output, VHO, and metal
halide lamps. To further complicate matters, there are
several types of ballasts available: electric ballast, magnetic ballast,
and pulse start ballast.
Luckily, the choice of lighting systems for a hobbyist
can usually be narrowed by first determining which types of
corals the hobbyist plans on keeping, since this is the
primary factor in determining lighting needs.
Heating & cooling
Most hobbyists agree that a reef tank should be kept at a
temperature between 78 degrees and 83 degrees Fahrenheit (26
to 28 °C). Radical temperature shifts should be avoided as
these can be particularly harmful to reef invertebrates and
fish. Depending on the location of the tank and the
conditions therein (i.e. heat/air conditioning), you may
need to install a heater and/or a chiller for the tank.
Heaters are relatively inexpensive and readily available at
any local fish store. Chillers, on the other hand can run
well over $400 USD and are more difficult to locate. For
many aquarists, installing surface fans and running home air
conditioning suffice in the place of a chiller.
External links
-
frags.org - Community that promotes coral
propagation, where you can buy, sell, and trade coral
fragments without ever taking corals from wild reefs
-
Geothermal Aquaculture Research Foundation,Inc.
Providving the citizens of Idaho and the world a
showcase collection of aquatic plants, fish, reef
animals and products.
-
AquariumDomain Complete Resource for the Marine
Aquarium Hobbyist.
-
Age of Aquariums Promotes responsible fishkeeping
internationally since 1997.
-
Marine Aquarist Association of South Texas (MAAST)
Forums dedicated to keeping marine aquariums.
-
Reef Aquarium Set Up Beginner's FAQs and Pictures.
-
Reefs.org - Reefs.org is the oldest internet
communitity solely dedicated to the hobby of reef
aquarium. Reefs.org hosts an active online bulletin
board, monthly magazine (www.advancedaquarist.com),
college-style courses related to reef husbandry (www.aquaristcourses.org),
a library of reefkeeping reference material, and the
oldest, most active reef internet live chat (#reefs).
-
Reef Central - Reef Central is dedicated to the
marine reef aquarium hobby. Learn about reef aquarium
setup and maintenance, and view coral and marine fish
photos.
-
The Marine Reef The complete community, for every
aquarist. The Marine Reef offers live chat, forums, and
a friendly online community.
-
Aquarium Pros - AP is dedicated to the Canadian
reefkeeping community, but contains a wealth of
information for any interested.
-
Advanced Aquarist's Online Magazine - An online
marine aquarist magazine covering all topics relating to
marine aquarium husbandry. Established in 2002.
-
Coral Reef Tanks and Aquariums - Resource for
starting and maintaining coral reef tanks and aquariums.
-
Marine Aquarist Courses Online - Online courses for
marine aquarist teaching such subjects as DIY projects
(skimmers, calcium reactors, etc), animal husbandry, and
equipment selection. Established in 2000.
-
Artificial Corals and Reefs - Can be used in
freshwater and saltwater aquariums. Environment
friendly. Helps to save natural reefs.
-
Reef Aquarium Index - Saltwater & reef aquarium
reference guide contains links to over 1500 articles on
set-up, maintenance, and care of fish & coral species.
-
Reef aquarium care articles and coral identification
guide with reef tank hobby community forum.
-
Reef Aquarium Wiki - MediaWiki-powered encyclopedia
of reefkeeping.
-
Wetwebmedia: Aquariums, Fish, and Aquatic Information
- Thousands of Articles & FAQ's.
-
SaltCity: Marine and Reef Discussion Forums -
Dedicated to the propagation of information.