Tanne Hoff's (Tanu)
Introduction and Background:
It is a very big
honor for me to have my tank being featured here as Tank of
the Month. I've been keeping marine aquariums for about 14
years since I was 10 or 11 years old, starting with a very
simple, small tank. It contained only some dead shells and
rocks, one piece of live rock, a feather duster and a small
sea star. As my experience and pocket money grew, I upgraded
the tank a little with some small damsels and shrimps.
Now, I'm a diver and a biology teacher so I have access to
an abundance of information which makes it easier for me to
understand what's going on in my tank. I'm also one of the
administrators of the Dutch Marine Aquarium Forum, www.zeewaterforum.net.
I've contributed quite a few articles to the Dutch Marine
Aquarium Magazine. It took quite some time, as well as some
successes and failures before the tank became what it is now.
My current tank was set up about two years ago.
The way I keep this tank IS successful, but I'm sure this
isn't the only way or even the best way. It just works for
When designing this
tank, I had several goals in mind. The first was to create
an environment in which the fish would feel comfortable. The
second was to keep lots of healthy small polyped stony (SPS)
corals. I didn't want to keep just a tank full of rocks, but
instead wanted to create plenty of "free space"
in which the fish could swim about and the corals could grow.
I also wanted the tank to be easy to maintain. Being a diver,
I've observed in nature that most fish tend to swim OVER the
corals instead of in front of them. I also didn't want the
rockwork looking like the Great Wall of China.
Thus, I didn't use much rock. I bought the tank and stand
second hand, and the tank had a very nice DIY
foam backdrop which I wanted to keep. To make a long story
a little shorter (I won't bother with discussing the accidents
which required me to buy new front AND side glasses!), I filled
the tank with RO water, added salt and the tank had begun
As I said before, I had some ideas
to incorporate into the aquascape. I used different techniques
to accomplish my goals. I used PVC tubing to connect some
pieces of live rock. Tie-wraps and epoxy were also used to
create an open, lightweight structure. I wanted the fish to
be able to swim and hide, and I also wanted the rockwork to
intermittently hide the fish from sight. I wanted to make
sure the fish didn't HAVE to see each other all time, thus
reducing aggression. I think I have used less than 100 pounds
of live rock in my tank, a fraction of the amount commonly
As mentioned earlier, the focus is
on small polyped stony corals together with fish. But in my
opinion it would be boring not to house other animals as well.
Shrimp, snails, hermits, brittle stars, sea stars, different
'softies' and other animals also fit in with my view of a
I have quite a few fish, and I strongly emphasize the fact
that I added these slowly over about two years. Adding all
these fish at once almost certainly would have lead to a tank
crash! Many people ask what the trick is to having good water
parameters even with such a high fish load. The trick is nutrient
removal; protein skimming, water changing, vacuuming the sand
bed and a huge amount of fast growing (i.e., nutrient absorbing)
corals are all very important. I think many aquarists too
often underestimate the impact of nutrient uptake by the corals.
Here's a list of my fish:
2 Yellow tangs, Zebrasoma flavescens - I've kept
the first Yellow tang for about four years. When I set
up this tank, I added another one, the smallest I could
find. In the beginning they fought a little, but later
they became accustomed to one another. Then, after about
18 months, some serious fighting occurred over a period
of about two weeks. The fighting stopped after about a
week or so. I haven't seen
any fights since then. Although these fish are among the
most common, they are also among the most beautiful!
Gem tang (below), Zebrasoma gemmatum -
I've been very impressed with these fish from the first
time I saw one pictured in a book but never saw one for
sale. It took me literally years to obtain one! Even in
Germany, nobody could sell me such a fish. I even made
plans for a holiday to Mauritius, where this fish lives.
At last, I was able to buy this one from a fellow reefer
who switched to a smaller tank, and this gem has been
in my tank for about one month now. So far, it's doing
Regal angel, Pygoplites diacanthus - Another 'second
hand' fish that was already in someone else's tank. I've
bought these fish at the LFS twice. Despite the fact that
they both ate like pigs, both died within two weeks. This
one, however, has been in my tank for nearly two years
now. He eats almost everything I offer straight from my
hands. I have found that he is NOT totally reef safe!
He has mowed down a rock full of blue/yellow zoanthids,
and because of his antics, I've had to remove a large
brown Tridacna clam, a red Blastomussa,
a red Lobophyllia and a green Trachyphyllia.
2 Flame angels, Centropyge loricula - As with
the yellow tangs, I added a second (much smaller) Flame
angel after a few years. These two have been co-existing
peacefully for about four years now. They do something
which appears possibly to be spawning, but I've never
seen any eggs.
2 Cherub angels (above), Centropyge argi
- These were already together in one tank at the store
where I purchased them. I added them to the main display
after letting them gain strength in a quarantine tank
for about a month. They spawn from time to time, and I
think I've seen eggs being released.
Sixline wrasse, Pseudocheilinus hexataenia - I
added this fish about five years ago.
2 False Percula clownfish, Amphiprion ocellaris
- This pair has been with me for roughly four years now,
and they spawn every few weeks.
2 Yellowtail damsels, Chrysiptera parasema - They
are very territorial and don't like each other one bit.
Both fish claim their own half of the tank and fight every
now and then.
2 Orchid dottybacks, Pseudochromis fridmani -
I think they have spawned occasionally, but I'm not sure.
I believe they are a mated pair.
14 Blue-eyed cardinals (above), Apogon leptacanthus
- These are mouthbreeders and stay close together in a
shoal most of the time. Typically, at any given time,
one or two males are carrying eggs.
Coral goby, Gobiodon okinawae - This little fish
hops from one coral to the next, protecting them against
coral-eating fish. The downside is that it also feeds
on some of the polyps.
2 Blue mandarinfish, Synchiropus splendidus -
I've kept the male of this pair for about six years now,
and about two years ago I added the female. They spawn
almost every evening. During this ritual I often notice
them releasing eggs and sperm. The trick to keeping these
fish is to provide them a tank which produces enough small
critters for them to feed on. Unfortunately, I've never
observed them taking any of the prepared foods I offer.
Lawnmower blenny, Salarias fasciatus - This might
be the coolest fish I have! He does a great job of removing
algae and providing entertainment for the people who watch
the tank. It is also the only fish I have named: Henk.
This name is also getting established as the Dutch name
for this fish!
2 Sailfin blennies, Emblemaria sp. - I added these
in June of 2004, but because they are so shy, I've seen
them only a few times.
As stated before, I like to keep a mix of different corals.
I think it is almost impossible to name all my corals. I've
counted more than 100 species of SPS corals and about 20 species
of other corals (buttons, leathers, gorgonians, etc.). I think
a nice array of photos says more than a list of species. I
acquired most of the corals as small pieces or by trading
with fellow hobbyists for coral fragments. I make between
100-200 small- to medium-sized fragments annually. I have
some special species that I'd like to emphasize:
Yellow scroll coral, Turbinaria reniformis - I
acquired this coral seven years ago, and it was almost
dead. The size of the remaining live tissue was about
1." It cost me only two €uros. I removed the
dead skeleton, and as you can see, the result is great!
I'm very proud of this coral.
Acropora sp. (formosa?) - Located in the upper
left corner of the tank. The mother coral was imported
about ten years ago. I obtained a fragment of this coral
from my local fish store. It grows like a weed! If I remember
correctly, about 60 fragments were taken in 2004! Even
after all the fragmentation, the size of the colony has
increased enormously. Compare this picture
to the overall picture of the tank at
the top of this article. The first photo was taken in
November 2002, the second in December 2004.
Pink birdsnest coral, Seriatopora hystrix - In
1996 almost no one in Holland had birdsnest corals at
all. Then, I received a phone call from my local fish
store wherein the owner told me they received six S.
hystrix, one of which was pink. A few days later this
coral was in my tank. Now, about nine years later, I still
have this coral, and I've traded many of its fragments.
Pink/Purple tabletop coral - The owner of the LFS gave
me a fragment of this coral. At first, it just grew like
a bush, and one of the branches started to grow as a table.
I fragged this branch, and it continues to grow like a
2 Blood shrimp, Lysmata debelius
2 Cleaner shrimp, Lysmata amboinensis
2 Peppermint shrimp, Lysmata wurdemanni
2 Sexy shrimp, Thor amboinensis
4 Red-legged hermit crabs, Paguristes cadenati
1 sandsifting sea star, Archaster angulatus
3 sandsifting snails, Strombus fasciatus
3 unknown serpent stars with 'bold' arms, these are also
safe with small fish (Ophiolephis sp.?)
The tank is an all-glass tank of 130 x 70 x 70 cm, containing
about 160 gallons. The front viewing pane is made of a special
kind of glass called optiwhite. While normal glass has some
green tint, this glass is as clear as acrylic yet has the
advantage of not being as sensitive as acrylic is to scratching.
It scratches more easily than normal glass, though. Located
directly under the tank is a sump which contains another 35
gallons of water.
I also have a small tank of 50 x 30 x 30 cm connected to the
system. This tank is not often used, but I put some new arrivals
into that tank to let them relax from transport and gain some
weight. I mostly do this with small fish for whom I expect
problems from the existing fish population. Both cherub angelfish
were the latest to spend a month in this small tank.
Main Circulation Pump
The heart of the system is a Red Dragon 10,000. I wanted a
silent pump that doesn't draw much electricity but still moves
a considerable amount of water. While this pump is almost
completely silent, it pushes roughly 10,000 l/h but uses only
98 watts! This pump is also the only means of circulation
in the tank. In my opinion it is very important to have as
much flow as possible between the sump and the tank, thus
making it possible for the detritus to reach the skimmer and
be removed from the system.
I use a three channel Trace-el-controller by Grotech (seen
below) to add trace elements. Grotech formulas A, B and C
are added at a dosage of 4 ml each day. I've tried to add
more or less, but varying the amounts reduced the corals'
colors. I've also tried some other brands of three-formula
additives, and I even tried mixing them myself. So far, I
haven't been able to beat the results I've seen with Grotech.
Sometime in the future, I might try the Zeovit method, but
I'm still debating its use. At this moment I also currently
use Salifert Amino Acids, and I believe that some corals show
better colors as a result.
Water Top-off and Calcium Reactor
I use an automatic water top-off system with reverse osmosis
water and synthetic sea salt. I mostly use Reef Crystals salt,
but every now and then I use some Instant Ocean or Sera. I
also intend to try Red Sea salt at some point in the future.
I add calcium via a custom-made calcium reactor (above right)
from my local fish store. I modified this reactor by adding
an injector which recirculates the excess carbon dioxide.
Using this method, it is possible to add much more calcium
with the same reactor. This reactor is not computerized and
runs continuously. Coarse coral
is used as the media in this reactor.
Light is provided by an Aquaspacelight with two 150-watt HQI
bulbs and two 24-watt power compacts. The fixture is about
5"above the water's surface. The HQI bulbs are BLV Hitlites;
the power compacts are typical blue bulbs from Osram. I change
the bulbs yearly. The HQI's are on for 12 hours/day, and the
power compacts for 13 hours. I've been using 150-watt HQI
bulbs for about nine years now, and I'm very satisfied with
this way of lighting the tank. In the very beginning I used
6500K bulbs, because nothing was available with a higher Kelvin
rating. Later, I switched to Aqua Medic 10,000K bulbs. This
year, I decided to try the BLV bulbs. These bulbs weren't
developed particularly for our hobby, and compared to the
Aqua Medic bulbs, they lean a little more toward the blue
part of the spectrum.
I use a Schuran Jetskim 150 skimmer.
According to the manufacturer this injector-powered skimmer
is able to clean 1000 L of water. It removes quite a lot of
waste. Every now and then I use some ozone (50 mg/h) for a
few hours to 'burn' excessive yellowing components from the
water. I also use activated carbon. I put the carbon in a
mesh bag; most water leaving the skimmer passes through this
bag. I use about one coffee cup full of carbon, and change
it when I think it is necessary, typically after about six
Water changes are also very important, in my opinion. I use
no other filtration. In the past I've also used filter floss
and I've tried zeolites but I've since decided to try to keep
things simple. Since I removed the filter floss, the skimmer
produces more waste. In the beginning I had more particulates
in the water, but now the water is as clear as it was originally.
Daily: overall checkup on the equipment for proper
operation and the animals are checked to determine if
they are all present and healthy. I also feed the fish
almost daily. Sometimes when I'm not home for a day they
have to find their food themselves. I think feeding is
underestimated. When I compare aquarium fish to fish in
nature, the fish in nature look fatter and healthier than
most fish I've seen in aquaria. I feed the fish OSI Spirulina
flakes and Duplarin granular food daily. I also feed dried
Nori-flakes daily; the Regal angel and the Gem tang eat
this from between my fingers. At least once per week,
I add vitamins to the food. I also feed frozen foods every
now and then: krill, Mysis, Artemia, chopped
Every few days: clean the collection cup of the
skimmer, clean the glass with an algae magnet, and fill
the top-off tank with fresh RO water. Dislodged corals
are returned to their original positions as noticed, but
I try not to reach into the water unless absolutely necessary.
I also use a pair of long tweezers and a PVC rod as tools
to reduce the time my hands are in the tank.
Every two weeks: I perform 15% water changes with
fresh synthetic saltwater. I vacuum the sand and suck
away detritus and unwanted algae. I also clean the glass
with an algae scraper to remove harder algae such as calcareous
algae. I let the skimmer suck up one liter of vinegar-laden
boiling water to remove dirt in the injector. After performing
this procedure, I see an increase in the skimmer's performance.
When needed: cleaning the skimmer, making coral
fragments. Additionally, the sand is replaced every so
I'm not an aquarist who measures very
often. Here are some of my parameters:
After the tank was set up, I battled the bubble algae, Valonia
sp. I tried to maintain good water quality, and I added a
Foxface fish, Lo vulpinus, to remove these algae. The
amount of Valonia significantly decreased. The Foxface
wasn't totally reef safe, though; when he started scraping
tissue off the Acropora, I returned him to the local
On my previous tank I used a very good skimmer which was connected
directly to the overflow. Because the stand of the new tank
wasn't as high as the previous one, it wasn't possible to
direct most of the water through the skimmer. The skimmer
didn't work very well anymore, so I added a Schuran Jetskim
150 which took quite some time to start working. In fact,
the tank was almost skimmerless in the beginning and I do
not recommend that.
Because I think a more powerful skimmer would benefit the
system, I've ordered a new skimmer, a Bubble King Intern 200
by Royal Exclusiv. This skimmer should be able to remove more
waste than the current one does. Waste removal is very important
for a tank like this, containing both a high fish load and
a large population of SPS corals. I also expect to need a
skimmer with some more muscle because of one of my future
Breeding and Fragment Growout
Quite a few fish spawn in the tank, and I regret the fact
I've never attempted to catch or raise any of the fry. Thus,
I'm toying with a plan to try to hatch some of the fry. I'm
busy designing a sump which incorporates both a fragment growout
tank and a fish growout tank. I prefer a 'clean' look in the
tank itself, and in my opinion dozens of frags don't fit well
with that look. I intend to light the growout tank with a
couple of T5 bulbs. My goal isn't to raise hundreds of fish
yearly, but if I could just raise one or two, I would be very
proud! Of course, raising more than just one or two would
I want to thank Reef Central for honoring
my tank with the Tank of the Month award. I also want to thank
my fellow aquarists around the world for giving the advice
and inspiration which have made this tank what it is today.
Feel free to comment or
ask questions about my tank in the Tank of the Month thread
on Reef Central.