What is a mini reef?
A mini reef is an aquarium containing many of the fish, corals
and invertebrates, that can be found in the earth's coral reefs. In general
these aquariums are teeming with life, (even the rock that is used is called
'live rock' because of the organisms found on it), compared to the traditional
marine aquarium with fish and coral skeletons for decorations. The main differences
between marine "fish only" systems and reefs are listed in the box.
| Marine vs. Reef |
| 1.
Filtered water, either reverse osmosis or de-ionized, is a must for
the reef aquarium. (It is also a good idea for the marine system
as well but is not absolutely necessary. )
2. Reef aquarium filtration generally includes
more of an attempt at controlling nitrates either through filtration
like protein skimmers and denitrification filters, through
the addition of live rock, or through more constant and larger
water changes. It is also desirable to limit phosphates by
using filtered top-off water and resins.
3. Lighting in a reef aquarium is generally much
more intense as it is trying to simulate sunlight in the tropics.
The spectrum is also bluer to simulate conditions at lower
ocean depths. Many of the corals require light of this intensity
and color to grow and flourish.
4. Several chemicals are monitored and adequate
levels are maintained in a reef aquarium. These include, calcium,
strontium, iodine, carbonate hardness, and trace elements.
5. Strong water currents are necessary in a reef
environment to bring nutrients to many of the 'filter feeding'
organisms and to carry away their waste.
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The difference between a marine aquarium and
a reef can be quite striking. The abundance of life in the reef aquarium
provides a visual treat that makes the traditional 'fish only' marine
aquarium seem almost sterile in comparison.
Mini Reefs are comparatively new to the aquarium hobby. Although
people had been experimenting with keeping corals, especially in "natural"
systems since the early 1960's, the 1980's and early 1990's saw the beginnings
of serious efforts to import, keep and breed many of the corals and invertebrates
available today in most shops that carry marine and reef animals.
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 Drs. Foster and Smith |
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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.
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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
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Marine Trace Elements
Trace elements are another group of chemicals removed by protein skimming. As
skimming is becoming more common in all marine aquariums, all of these
supplements 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
