Mike O'Brien's (mojoreef) Reef Aquarium
Introduction & Background
I would first like to thank the folks
at Reef Central and Reefkeeping Magazine for choosing
my tank as the Tank of the Month. With all the unbelievable
tanks out there to choose from, I am truly honored to be
selected. I have been involved with keeping an aquarium
of one kind or another for the past few decades, and have
progressed from fish-only to soft corals and have eventually
ended up with a mostly SPS-type of tank. My first marine
fish-only tank was started about 19 years ago, keeping bleached
out coral heads with a purple substrate for decor and the
meanest fish I could find. As this tank matured and I began
scuba diving, I started to collect my own corals such as
mushrooms and polyps. I even remember collecting dead coral
heads to use as decoration. In 1987, I began to pursue some
of the harder-to-keep species of fish and corals, and had
a fairly good success rate at keeping these critters alive.
For many years, I followed the European system of aquarium
keeping, as there was not much available in North America
in the way of reefkeeping knowledge (or at least what I
had access to). As the years passed by, I took several marine
biology courses attempting to educate myself on the corals
and creatures I was keeping, and to improve my husbandry
skills. Well, all this has led me to where I am today. I
am now what one could consider a person who has taken this
hobby way too far
or just plain crazy, as my wife
Since starting in the hobby I have kept
dozens of tanks and have gone up and down in their sizes
and number, but about nine years ago my wife gave me an
ultimatum and told me that from this point on I was restricted
to just one. However, luckily for me, she made the mistake
of not saying how big it could be! Not too long after that,
I was offered the option of creating a tank of whatever
size and shape I desired from a good friend working at Innovative
Aquarium Products. So, being the fanatic that I am, I built
this one. Many months of thought and years of experience
went into its design to make it one I could be proud of.
This is how it came out
gallon main display
gallon acrylic sump
65 gallon refugium/grow-out tubs
workrooms behind tank
The tank is an L-shaped, 650-gallon display,
custom-made by Innovative
Aquarium Products, consisting of two eight-foot long
viewing panes. The front-to-back depth on the left side
is two feet and the right side is three feet, with both
sides being 30" high. The tank is constructed of ¾"
clear Plexiglas, but with black Plexiglas used on both the
back and at each end. I elected to go with Euro-style bracing
around the top edge that is 1 ½" thick, with
three 11" wide cross braces for added lateral support.
The tank has three main overflow boxes (10" deep x
6" x10") and they are all connected by an overflow
trough (4" x 4") that spans the entire length
of the back inside wall of the tank. This new tank replaced
a perfectly good, but too-small-for-a-crazy-reefkeeper,
tank that had been in operation for about two years.
Two pictures taking during construction showing the area
that will house the tank and the workrooms behind the tank.
The stand is built out of 6 x10's, using
mortice and tenon style joints, and fastened using 8"
The skin of the stand and the top of
the tank is finished with tumbled marble tiles and wood
trim; additionally, a small section of decorative hand-painted
tiles (see below) is located on the front. Four hatchways
(36" x 15") are built-in above the tank for easy
access from the front.
Since I believe in providing vigorous
water flow, a lot of time and effort went into building
and planning the plumbing system for the tank. The main
return is powered by an Ampmaster 3000 and feeds back into
the tank via a 1 ½" spray bar located behind
the rocks. This keeps any and all detritus from settling
behind, or under, the rocks. Additionally, there are two
separate closed-loop systems, each powered by a 5000 GPH
Dolphin pump with its intake plumbed into two 1 ½"
bulkheads. From these pumps the water is sent to a 3-way
Hayward motorized ball valve which allows
the flow to be directed between two different banks of returns.
On each side of this valve are six ¾" inputs
into the tank, capped with adjustable LocLine on the
inside. This plumbing scheme has allowed four zones of circulation
to be created within the tank. At any given time two of
the zones are putting out chaotic flow while the other two
are in a slow and even flow mode. Roughly every five to
seven minutes, the Hayward valve turns over and reverses
the direction of flow, simulating the effect of a wave crashing
down for the first setting, followed by a calm and even
flow when the valves reverse. Eductors are used on five
of the LocLine returns and this increases the water
flow coming out and into the tank by roughly five times.
Since there is a combined output of 13,000 gallons considering
all of the pumps employed, and the use of the eductors,
a rough guess on the amount of turnover in the system would
be somewhere around 35,000 gph.
A couple of shots of the closed-loop system showing the
valve (top) and the closed returns (bottom).
to see a larger version with each item labeled.
For filtration, the system uses three
separate tanks: an acrylic sump (72" L x 20" W
x 25" D), and two 65-gallon Rubbermaid stock tanks
(approximately 48" L x 30" W x 10" D), which
are mounted in a rack system. The top refugium has one inch
of fine sand where about 30 mangrove trees are grown to
aid nutrient export. This tank has never been lit directly,
but gets incidental light from the main tank. From here,
the water then bleeds down to the second Rubbermaid tub,
and is then directed back to the acrylic sump. The second
Rubbermaid tank is used a coral fragment grow-out area.
The mangrove refugium (top) and the fragment grow-out tub
The system was designed and plumbed
based on the idea of providing a random alternating current
that would be strong enough to keep the detritus and dissolved
organic compounds suspended in the water column, thereby
allowing them to be exported from the main tank via the
overflow and filtration systems (skimmer, mangrove refugium,
UV sterilizers, carbon filters and the phosphate filter).
As described above, the overflow system pulls the whole
top of the water column off at one time and leaves no dead
spots, thus completely eliminating any surface film build-up.
The two chambers on the left are the carbon and phosphate
The three on the right are the UV sterilizers.
From these overflow boxes,
water flows into the first chamber of the acrylic sump,
where it is fed into a twin tower ETSS 2500 skimmer powered
by a ½ hp RK2 pump. Just prior to the skimmer towers,
the input pipe is branched off into two more one-inch lines.
One line diverts water into the two Rubbermaid stock tanks,
with the other line running outside the house to a ¾
hp chiller, after passing through a chamber containing the
inline probes connected to the Octopus 3000 controller.
After the cooled water exits the chiller, it's routed back
through three 40-watt Rainbow Lifeguard UV sterilizers,
a 37" carbon filter and another 37" phosphate
filter, finally returning back to the main acrylic sump.
The carbon and phosphate filters are plumbed so that they
can be bypassed, or put into operation, as needed.
The main sump. Click on the picture to see a larger version
with each item labeled.
For biological filtration
the main display tank contains just under 1000 lbs. of live
rock, resting on the PVC spraybar structure and consisting
of assorted pieces collected over the last 10 years from
Fiji, the Marshall Islands and Tonga, as well as a few more
types. When initially setting up the tank, the rock was
aquascaped in a dry tank and then filled with natural sea
water obtained from local waters. A one-inch layer of crushed
coral is used as the substrate in exposed open areas, as
I am not a big fan of the bare bottom appearance, although
future plans may include removing the crushed coral once
(and if) it becomes phosphate laden.
The lighting of the main display can
be separated into two sections, each with a different lighting
regime. The right portion of the tank is intentionally lit
to accommodate the high light demanding corals (Acropora
spp., Montipora spp., Porites spp.) and the
back (or left) section of the "L" shape is moderately
lit and houses LPS and a large leather coral. On the right
section the lighting is attached to one-inch plywood connected
to a barn door rail, which allows the entire
lighting system to be moved out of the way to work in the
main tank. The lights in this area are a mix of 10K Ushio
and 20K Radium metal halides; there are four 10K HQI 250
watt bulbs and three 400 watt 20K Radium bulbs, all housed
in SpiderLight reflectors. Additionally, I also have
four 48" T-5 Aquastik blue fluorescents. The back section
of the "L" has two 250 watt 10K Ushio bulbs mounted
in Prism pendants containing four 38-watt actinic
Although the mangrove tank has a 100-watt
grow light, I have never used it, as the mangroves seem
to grow quite well without it. On the fragment grow-out
tank there are two 175-watt Ushio bulbs that are run on
a reverse daylight photoperiod, and this is done mainly
for heat reasons.
All of the lights are controlled by an
Octopus 3000 controller with X-10 modules that turn them
on in series from one side of the tank to the other and
then turns them off in opposite fashion. The lighting schedule
begins at 9:00am with the first two banks of T-5's, then
progresses to turn on a metal halide bulb every fifteen
minutes until all nine are on. The first metal halide bulb
turns off at 8:00 pm and the lights then turn off in reverse
order, finishing once again with the T-5's and power compacts.
When the frag grow-out tank is stocked with corals, its
lighting turns on after all the main tank lights are off.
For moonlight, two 25 watt blue party bulbs have been placed
on a "Caribbean type" photoperiod programmed by
the Octopus controller, but lately this has been shut down
to control the spawning events.
The rail system can be seen here above the reflectors.
Located directly behind the tank are
the workrooms which house the majority of the equipment
needed to operate the system. The rooms are heavily vented
with three exhaust fans to pull out the excess heat and
humidity. The main workroom is approximately 10' x 10' but
there is also another room directly behind the tank that
is about 7' x 8'. The walls of the rooms were built out
of marine grade plywood and coated with a shiny laminate;
all of the joints and fasteners were caulked to prevent
moisture penetration. The room contains a large, janitor
style sink and a 100 gpd ro/di unit. To keep the light from
entering the main tank at night, there is a pull-down blind
that shields the frag/mangrove tanks from the main system.
Alkalinity: ~11 dKH
Specific Gravity: ~1.025
Temperature: 79 - 80°F
pH: ~8.25 - 8.35
Phosphates: no detectable inorganic phosphate
A Deltec 1000 calcium reactor supplies
most of the calcium and carbonate the tank requires. I have
to give kudos to this unit as the amount of calcium and
carbonate it produces is truly unreal. This is the best
unit I have ever seen or used.
The Deltec calcium reactor is seen here on the right along
with the ETSS skimmer on the left.
The calcium reactor is run only when
the lights of the tank are on, but when the main display
lights go off, an analytical grade calcium oxide kalkwasser
from Warner Marine is dosed. The kalkwasser is mixed-up
weekly in a 55-gallon drum and then delivered to the tank
using a metered pump. Beyond this, no further supplements
are added unless testing shows a lower level of magnesium,
in which case I dose accordingly.
The kalkwasser tub with the dosing pump mounted on the top
Surprisingly, there is not as much maintenance
to this tank as one may think. The skimmer is adjusted to
pull out a wet skimmate (about 5 gallons every two weeks)
so this must be emptied, but I only have to clean out the
skimmer itself once every two weeks. The glass is cleaned
of coralline algae every weekend. Luckily, I don't get any
slime algae on the tank face; the tank is pretty much devoid
of algae with the exception of coralline. Initially, the
maintenance routine included out vacuuming the crushed coral
substrate once a month, but I found that the accumulation
of detritus is very low, so this chore is now performed
once every two months. Also, as mentioned earlier, a new
batch of kalkwasser is created on a weekly basis.
With the processing capabilities of the
equipment and the extensive filtration built into the system,
I do not perform any water changes. So, on this tank there
have been no water changes in 11 months and on the prior
300-gallon tank there was none done for the two-year period
it was in operation. However, I must say that I do not recommend
this to many hobbyists, unless they have the ability to
process the water as this system does. Beyond occasional
testing of water parameters, this is about all the maintenance
I do on the tank.
I make my own food for the tank and feed
daily. It's a simple mixture of shrimp, clams, cod, scallops
and nori, with Selcon added and then blended together
to create a variety of different sized particles. By feeding
in this manner nearly all the organisms in the system are
fed at once. There are, however, a couple of non-photosynthetic
gorgonians that are target fed a small amount of phytoplankton.
Top-off water is provided by an Oceanus
four-stage ro/di unit, containing an additional carbon canister;
the unit produces approximately 100 gallons per day. Attached
to this filter is a permeate pump, which allows up to 85%
of the wastewater to be saved by recycling pressurized wastewater
back through the reverse osmosis membrane. The output of
the RO/DI system is plumbed into the sump using a Kent float
valve that turns the system on and off as needed. The system
typically evaporates anywhere from 3-5 gallons per day.
The system doesn't have too much need
for heat, as you can imagine with so many lights in use,
but there is an 1800-watt bayonette style heater and two
300-watt Ebo-Jager heaters for redundancy as an added precaution.
A ¾ hp CustomSeaLife chiller, set up in its own area
located outside, is used to cool the tank.
The system is controlled by an Aquadyne
Octopus 3000, which controls most functions of the tank's
operation, including such things as simple timing routines
for the lights, to fail-safe setups through the monitoring
and controlling of the calcium reactor, kalk doser, skimmer
and so on. Also connected to the tank are six normally-closed
(NC) valves. With the size of this tank and the quantity
of water that the entire system contains (mangrove tank/frag
tank/skimmer/chiller), it's tough to build a sump large
enough to accommodate drain down of the system during a
power outage. To combat this, I use the NC valves so that
when a power outage occurs they all close and prevent the
water from draining into, and overflowing, the sump.
1 Vlamingii tang
red tail fairy wrasses
1 copperband butterfly
Red Sea sailfin tang
green feather stars
3 skunk cleaner shrimps
large coral banded shrimp
2 very large brittle stars
serpent star (in refugium)
rock boring urchins
1 long spined urchin
blue Linckia and one red
There are about 80 SPS colonies in the
tank, mostly Acropora, but also Pocillopora, Stylophora,
Porites, Montipora spp. I also have a 23 head
frogspawn that is about the size of a basketball, a large
finger leather and a couple of torch corals. Additionally,
there are some polyps, zoanthids and Tubastraea spp.
To learn more about Mike's
system, visit his website by clicking on the image below:
Feel free to comment
or ask questions about my tank in the forum
for the online magazine.