https://www.facebook.com/doug.monahan Do you love saltwater aquariums just like Doug Monahan? Here is a great guide that he follows.

1. Saltwater aquariums
Successful setup
Natural care
67 guide

2. The sea: An incredible living world ......... 3
Which marine animals are suitable
and which are not? .................................... 4
Preparing your natural biotope .............. 7
Aquarium setup:
The substrate .............................................. 8
Biofilter components ................................ 9
Biofiltration ................................................. 10
Technical equipment ................................. 11
Saltwater ...................................................... 12
The landscape ............................................. 13
The new environment
needs time to grow ................................... 14
Introducing and acclimatizing
the marine animals .................................... 15
Every animal has its own
nutritional requirements .......................... 16
Healthy treats & specialties ...................... 17
Regular maintenance:
Checking the water ................................... 18
The interaction of pH, CO2 and
carbonate hardness ................................... 22
From ammonium to nitrate:
The nitrogen cycle ..................................... 24
The calcium level ........................................ 26
Strontium and trace elements ................ 27
What to do if a marine
animal gets sick? ........................................ 28
What you always wanted
to know about saltwater .......................... 31
2
Contents
2

3. 3
Almost two thirds of the earth’s surface is covered with water
– the vast majority of it open ocean. Yet with all this area, the
highest concentrations of fish species exist close to the coral
reefs and atolls. Many of the species living in shallow regions
can make a comfortable home in saltwater aquariums, as they
prefer moderate or warm tropical water and little space.
A reef aquarium itself is a small ecosystem influenced by
many factors. Over the years, aquarists have had more and
more success in keeping soft corals for long healthy lives and
finding success at breeding marine fish, which had proven
difficult for many years.
Before setting up your own saltwater aquarium, take a few
minutes to look through this guide. In it you’ll discover the
first, but most important, steps to setting up a stunning,
healthy saltwater aquarium. This guide is not meant to
replace the necessary technical literature that explains and
guides you through the exact care for specific organisms –
but instead it will help you identify the basics, so that you can
do further research on your own. Enjoy the experience!
3
The sea: An incredible living world

4. Which marine animals are suitable
and which are not?
Easy-to-keep fish for first-time marine aquarists
4
First, let’s look at the inhabitants of a saltwa-
ter aquarium. If corals, shrimps, and other in-
vertebrates are to be kept in the same aquar-
ium, your choice of compatible fish is
reduced. Many fish are predators, and will
eat smaller fish, shrimps, or coral tentacles.
Even peaceful fish can cause problems:
Seahorses, for example, must be fed fre-
quently, which can lead to water pollution,
and they are notoriously slow eaters – so
their food is often eaten by other fish. An-
thias species are very beautiful but also very
demanding fish.
Damselfish (Chromis, Dascyllus, Chrysiptera) Gobies (Cryptocentrus, Valencienna)
Cardinal fish (Sphaeramia, former Apogon) Clownfish (Amphiprion)
Wrasses (Macropharyngodon) Surgeonfish/Tangs (Acanthurus, Zebrasoma)
These fish can be kept in the same aquarium
as invertebrates:

5. Corals
Which marine animals are suitable
and which are not?
5
Some corals live in a symbiotic relationship
with unicellular algae called zooxanthellae.
These organisms live in the coral’s tissue,
providing them with all nutrients they
require – without being fed by humans!
Other coral species do not feed via zooxan-
thellae, and must be fed, which leads to
heavily polluted water conditions. sera rec-
ommends avoiding these species – such as
Pennatulacea sp. (sea feather), Lemnalia
Africana (soft corals), and Tubastrea sp. – at
least during the early stages of your marine
aquarium experience.
With well-maintained water, these inverte-
brates make hardy aquarium inhabitants:
Leather corals (Sarcophyton, Lobophyton,
Sinularia)
Mushroom anemones (Discosoma)
Anemones (e.g., symbiotic anemones for
clownfish)
Colonial anemones (Protopalythoa, Zoan-
thus)
With some experience also stony corals
(Acropora, Porites, etc.)

6. Which marine animals are suitable
and which are not?
6
Shrimps
While many shrimp species are easy to keep,
one of the most colorful and fascinating
shrimps is the Hippolysmata grabhami,
known as the “White banded cleaner
shrimp”. This shrimp not only cleans-up food
leftovers but cleans the ectoparasites from
your fish as well!
Sea urchins
Although most sea urchins live on a variety
of sea grasses many feed on decaying organ-
ic matter or algae – making them wonderful
housekeepers for your marine aquarium.
Sea cucumbers
Known for their cucumber-shaped body,
these animals eat plankton and decaying
matter that is suspended in the water or
buried in the sand. Consult your retailer
before buying a sea cucumber, though,
some species can release sticky or toxic sub-
stances into the water.

7. Preparing your natural biotope
7
Aquarium size
Keep this rule in mind when choosing an
aquarium: The larger the aquarium, the eas-
ier it is to maintain.
Larger volumes of water are less easily dis-
rupted by a small fluctuation to water
parameters than smaller volumes because
the change has more area in which to dissi-
pate – the parameters remain fairly constant.
The same fluctuation to a smaller volume of
water could provide a severe jolt to the
whole biological condition.
Aside from water parameter considerations
when buying an aquarium, you also need to
consider the fish. Most marine fish require
substantial territories to defend. For these
reasons, sera recommends a 200-liter (53 gal.)
tank, or a 100-liter (26 gal.) at the minimum.
If a bio filter system, a trickle filter for exam-
ple, is to be installed under the aquarium,
ensure that a sufficiently large overflow hole
is drilled as a water outlet.
Optimal lighting
Fluorescent tubes, metal halide lamp (HQI) or
their successors HCI or CDM, or a combina-
tion of both, are used for lighting saltwater
aquariums.
If fluorescent tubes are used, the water
depth must not exceed 50 cm (20 in.). You
can use the sera Combi-Reflectors to
increase light intensity by up to 100%.
For a double-hood aquarium using
fluorescent tubes only, sera rec-
ommends combining light spec-
trums for optimal conditions.
Consider the sera deep sea
special as a foreground tube; it
provides actinic blue marine light
and, with a specific light spec-
trum of 380 – 450 nm, it ensures
tropical reef light conditions.
Growth and coloration of inver-
tebrates are strongly enhanced
by the blue light spectrum. We
recommend the sera blue sky
Royal for supplying the saltwa-
ter tank with tropical daylight.
Always combine a metal halide lamp with a
blue light tube – the sera deep sea special
for example – in aquariums stocked with
invertebrates that require plenty of light, or
if the aquarium is deeper than 50 cm (20 in.).
This ensures the best possible display of
your corals’ magnificent color.
Support and location
Place the aquarium on a Styrofoam or foam
pad (sera thermo-safe) to prevent the glass
from cracking. Install the aquarium away
from direct sunlight to reduce the risk of
algae growth.

8. Aquarium setup: The substrate
8
The most important task of the substrate is to provide addi-
tional settling space for bacteria with a high oxygen demand
(aerobic) in the upper layers, and for bacteria that live with-
out oxygen (anaerobic) in the lower layers.
Coarse coral sand is the ideal choice for a saltwater aquarium.
It is visually attractive, and because of its high lime content it
helps stabilize the pH value.
Some fish species, such as wrasses and gobies, need a sandy
area to dig themselves into for the night. A separate area with
coral or quartz sand should be provided for these animals.
Consult your retailer for details on the proper depth for your
specific fish species.
The remaining surface should be covered with a coarse coral
sand layer of about 3 cm (1 in.). sera recommends using a rock
border between the different substrates to prevent them
from mixing.

9. Aquarium setup: Biofilter components
9
1. Prefiltration
(Mechanical water purification)
sera filter wool and sera biofibres catch the large, solid dirt
particles – such as uneaten food or clumped dead algae –
from entering your primary filter. This prefilter media must
be cleaned regularly to maintain the maximum water flow
rate, and to prevent additional pollution from the decaying
particles. The prefilter’s primary focus is to give the biofilter
the best chance at breeding bacterial colonies, undisturbed.
2. Main filtration
(Biological water purification)
Your biological filter is home to the useful bacteria that bio-
logically break down the pollutants in your aquarium. sera
biopur and sera siporax provide the ideal settling conditions
for this bacterial colony. One liter (10 oz.) of sera siporax has
the same biological breakdown capacity as 34 liters (approx. a
9 gal. pail) of ceramic material. To collect any stray large dirt
particles, separate the sera biopur and sera siporax with an
additional layer of sera biofibres. We also recommend adding
a regular dose of sera ammovec, nitrifying bacteria for salt-
water aquariums, to your biofilter.
Clean this filter as seldom as possible to avoid destroying the
bacterial colonies, which already struggle to multiply in salt-
water conditions.
The saltwater is purified in several steps within the sera inter-
nal biofilters B 200 and B 400.
sera filter wool
sera super carbonsera biopur
e.g. sera siporax®
sera biofibres
sera biofibres

10. Aquarium setup: Biofiltration
10
Biological breakdown of
pollutants within the
filtering cycle
Millions of useful sera ammovec
nitrifying bacteria settle within
sera siporax to clean the aquari-
um water.
The large open-pored tunnel structure
of sera siporax provides a natural living
space for these microorganisms, which
convert clumps of dead algae, uneaten food,
and fish waste into ammonium. Each sera
siporax ring is composed
of a highly porous material
that ensures that a thick
layer of outer bacteria
develops and is supplied
with nutrients and water
for growth. As the inner
pores fill-in, a low-oxygen
thriving bacteria inhabits
the ring centers. These
break-down nitrate and release beneficial
nitrogen into the water.
sera ammovec nitrifying filter bacteria
convert clumps of dead algae, uneaten
food, and fish waste into ammonium.
Ammonia and ammonium are then con-
verted to nitrite by a second type of filter
bacteria.
Yet a third form of bacteria converts the
nitrite into nitrate. As nitrate promotes the
growth of algae and is especially harmful
for invertebrates, a slow flux filter with
sera siporax provides a dedicated solution
by biologically breaking-down the nitrate.
Skimmers reduce pollution in saltwater
caused by protein and other organic sub-
stances. They must be cleaned regularly to
prevent skimmed-off waste from re-enter-
ing the aquarium.

11. Aquarium setup: Technical equipment
11
Filter
The sera internal biofilter B was developed
according to the requirements for optimal
filtration. It is easily
accessible from the
top, so the prefilter
media can be changed
without disturbing the
biologically active pri-
mary filter media. With
its practical three
chamber design (see
pg. 9), this filter lets
you exchange a variety
of filter media, such as
active carbon, as necessary, without disman-
tling the entire filter.
The integrated surface skimmer of the sera
internal biofilter B reliably removes organic
waste and unwanted surface protein film.
You can achieve increased filtering perform-
ance from internal filters that use a sponge
cartridge by using sera siporax in the pri-
mary filter chamber, and sera biofibres or
sera biopur in the prefilter.
The sera internal filters L 60, L 150, and L 300
are ideal for quarantine, breeding, and live
food aquariums up to 300 liters. In addition
to water filtration, they also oxygenate the
water, and the fine-pored external sponge
prevents small animals,
such as sea cucumbers,
from being trapped in
the filter.
Thermostat control heaters
The sera aquarium heaters should be placed
in the clear water chamber of the sera inter-
nal biofilter B to prevent wandering inverte-
brates, such as anemones or snails, from
being caught and injured.
Pumps
Powerheads are the heart of a saltwater
aquarium. They provide the animals with
natural water movement and changing cur-
rents such as high and low tide, which can
easily be imitated by timers.
Correct placement is critical to ensure there
are no “dead spots” in which food and decay-
ing matter can accumulate.
To achieve the constant motion, use several
sera submersible pumps to keep the water
moving in front and behind the live rock.
With sera submersible pumps, the water
intake pipe can be protected by a sponge.
Thus, small animals are prevented from
being trapped inside the pump.
50 watts
18.5 cm/
7.3 in.
25 watts
18.5 cm/
7.3 in.
150 watts
30 cm/
11.8 in.
100 watts
22 cm/
8.7 in.
75 watts
22 cm/
8.7 in.
300 watts
35 cm/
13.8 in.
250 watts
35 cm/
13.8 in.
200 watts
30 cm/
11.8 in.

12. Aquarium setup: Saltwater
12
As the use of natural saltwater is not practi-
cal, aquarium saltwater must be prepared
from purified (reverse osmosis) water and
sea salt. Saltwater organisms in aquariums
require stable, constant salt conditions. sera
sea salt dissolves rapidly and homogenously
throughout your aquarium to form crystal
clear saltwater. The natural pH and KH bal-
ance forms a buffer that maintains a precise
and correct pH range. sera sea salt is free
from nitrate, silicate, and phosphate, and its
prepared saltwater has the biologically cor-
rect calcium and magnesium levels.
Sea salt: The crucial starting
point
Preparing the aquarium
water
Fill the empty aquarium with purified
(reverse osmosis) water and add
the prescribed amount of sea
salt. sera sea salt dissolves with
no residue. When the last salt
grains disappear, condition the
water with sera aqumarin. Use
powerheads, placed on the
aquarium floor, to agitate the
water for 24 hours. Use a ther-
mostatically controlled heater
to warm the water to the
desired temperature.
There are two methods:
1 When the free floating sera hydrometer
is used for testing, it displays the densi-
ty of the water on an integrated scale. For
example, in aquariums with inver-
tebrates, the density should be
between 1.022 and 1.024 g/cm3 at a
water temperature of 25°C (77°F). If
the temperature of the aquarium
water differs from this value, then
the estimated density would need
to be converted in accordance
with an appropriate table, such as
the one below.
2 The salt concentration of brackish water
or saltwater as well as the total pollution
degree of freshwater are determined via the
conductivity. The sera conductivity meter
can be easily switched from the µS/cm
(freshwater) to the mS/cm (saltwater) range
and thus has a broad
application range. It is
ideal for owners with
many aquariums, for
breeders, and for the spe-
cialty trade. Further appli-
cations are, for example,
quality control of R/O
(reverse osmosis) water,
and monitoring the water
for salt that might be
released by the decorations or active carbon.
Salt concentration too high: Dilute with puri-
fied water.
Salt concentration too low: Raise by carefully
adding sea salt.
Adjusting for exact salinity
16°C 1.025 g/cm3
1.026 g/cm3
1.0265 g/cm3
20°C 1.0235 g/cm3
1.025 g/cm3
1.0255 g/cm3
25°C 1.022 g/cm3
1.023 g/cm3
1.024 g/cm3
28°C 1.0215 g/cm3
1.0225 g/cm3
1.023 g/cm3
30°C 1.020 g/cm3
1.0215 g/cm3
1.0225 g/cm3
Density
at
Salinity
33 ‰
Salinity
34.5 ‰
Salinity
36 ‰

13. Aquarium setup: The landscape
13
There are no limits to your underwater landscape design
when you use your imagination. Ensuring the construction is
stable, though, is important. Aquarists often use all-plastic
cable fasteners and silicon to secure the decorations.
Place an acrylic panel at the bottom of the aquarium to pro-
tect the glass against damage from the constructions.
The aquarium should preferably be decorated with “live
rock.” Why it is called “live” will be obvious after several days.
Along with the live rock, dolomite, sand stone, granite, lava
rock, and tufa are other choices.
Fish, crabs, and other animals in the saltwater aquarium
need stones for hiding. Shelters, caves, and ledges are simple
to build with reef rocks.

14. The new environment needs time to grow
14
Development of
useful bacteria
After you have decorated your aquatic
world, it needs some time to colonize sever-
al strains of bacteria, which will break down
pollutants and inhibit the rise of
dangerous ammonia and nitrite
levels (see page 10). Bacteria
multiply slowly in saltwater envi-
ronments, so we recommend
giving your aquarium a head
start by adding sera ammovec
nitrifying bacteria.
During this start-up phase, ammonium and
nitrite levels should be monitored frequent-
ly with the sera ammonium/ammonia-Test
and sera nitrite-Test. When values are in a
safe zone, invertebrates and fish can be
introduced over the course of time. Check
with your specialty retailer for advice.
Watch your aquarium come
to life!
Many small animals and almost certainly a
variety of beautiful algae species will have
entered the aquarium with the “live rock,”
and will become visible as days go by.
If any of these animals, such as sponges, do
not survive, they must be removed immedi-
ately to prevent pollution as a result of
decay. In any case, another dose of sera
ammovec should be added.
Lighting
For the first week, refrain from turning on
the aquarium lighting to prevent detrimen-
tal algae growth.
Begin lighting the second week, increasing
the time by an hour or two a day. The live
rock begins developing, and every day there
are new organisms to discover. You will see
anemones, ornamental algae, crustaceans,
and other animals populate your miniature
reef.

15. Introducing and acclimatizing the marine animals
15
Some marine animals must never leave the
water. During transport, even a few seconds
of exposure to air can be lethal. Among
these air-sensitive animals are sea urchins,
sea cucumbers, starfish, and pufferfish.
When purchasing these animals, ensure they
are placed in the transport bag under water,
and ask your retailer for specific instructions
on introducing them into your aquarium.
Generally, the transport bags with the newly
purchased fish and invertebrates should be
opened and securely placed side-by-side in a
bucket, and for the following half-hour, drip
aquarium water into the transport bags. An
air hose fitted with a suction cup and clamp
is ideal for this job. By doing this, the animals
can adapt to the new water temperature as
well as the new water parameters. Place the
bucket in a darkened area to reduce stress
and help calm the animals.
When the new inhabitants are acclimatized
to the aquarium water, carefully transfer
them to the aquarium. A large glass contain-
er is ideal for moving them. Remember that
they must never come in contact with air!
sera aqumarin supports the fish’s healing
processes of the mucous membrane if it has
been damaged during transport.
Always purchase bred animals
when possible – and only those
that are suitable for your aquar-
ium!

16. 16
Every animal has its own nutritional requirements
Staple diets
Compared to freshwater fish, marine fish
require much more iodine and other miner-
als. More than fifty different ingredients in
sera fish foods ensure a well balanced diet
for the aquarium inhabitants. This helps sup-
port the immune system and prevents defi-
ciencies. All sera foods are especially low in
phosphate.
sera marinvit plus for ornamen-
tal algae, stony corals and other
invertebrates. This nutrient
complex contains strontium and
trace elements in biologically
correct amounts.
sera coraliquid, a plankton-
based, energy-rich liquid food,
was specially developed for fil-
trating invertebrates.
sera GVG-mix marin is a flake
food with added tidbits for
marine fish. This versatile
basic food contains iodine
and other minerals from
marine algae, krill, plankton,
and other valuable ingredients
such as bloodworms, daphnia, and artemia
shrimps.
sera granumarin is an ideal
food for fish that search for
their food between coral
branches, in the middle of
the water, or near the bot-
tom. It sinks slowly, softens
quickly but nevertheless
keeps its solid consistency.
Therefore, water pollution is largely avoided.

17. 17
Healthy treats & specialties
17
sera flora provides herbi-
vores (plant eaters) with
essential vegetable pro-
teins, minerals and rough-
age.
sera O-nip tablets consist of
50% freeze-dried food ani-
mals and 50% high quality
flake food, making it an ideal
diet for all animals. sera O-nip
tablets can be attached to
the aquarium glass, and will bring even shy
animals into view.
sera Spirulina Tabs can also be
attached to the aquarium glass.
This all-vegetable tablet con-
tains an optimal 20% of spirulina
algae for proper nutrition. sera
Spirulina Tabs are indispensable for algae-
eating animals such as surgeonfish/ tangs or
blennies.
sera Plankton Tabs contain an
especially high amount of
freeze-dried plankton. Fish are
fed by simply dropping the
tablets into the aquarium.
Invertebrates are fed individually, for exam-
ple, with a pair of tweezers or a plastic tube.
sera FD Shrimp, made of
tender brine shrimp is a
tasty treat for all saltwater
fish.
sera microgran for young fish
and small mouthed species is a
nutritious blend of ingredients
plus added multi-vitamin com-
plex, making sera microgran a perfect staple
diet for these fish.
sera micron is best suited for
raising fish fry or shrimp lar-
vae. Invertebrates and fish that
need powdered food can also
be fed sera micron.

18. 18
Regular maintenance: Checking the water
Parameter
When to check?
pH
Weekly
KH Carbonate
hardness
Weekly
Ca
Calcium
Weekly
Conductivity
Weekly
Density
Weekly
NH4/NH3
Ammonium/
Ammonia
Weekly
NO2
Nitrite
Weekly
Ideal parameter
8.0 – 8.5
8 – 12°dKH
400 – 450 mg/l (ppm)
50 – 54 mS/cm
1.022 – 1.024 g/cm3 at 25°C (77°F)
Ideal: 0.0 mg/l (ppm)
Dangerous from 0.02 mg/l (ppm)
Depending on the pH value
Ideal: 0.0 mg/l (ppm)
0.3 – 0.9 mg/l (ppm) NO2 (equals
0.1 – 0.3 mg/l [ppm] NO2-N): water
pollution
From 0.9 mg/l (ppm) NO2 (equals
0.3 mg/l [ppm] NO2-N): danger to fish
3.3 mg/l (ppm) NO2 (equals 1 mg/l
[ppm] NO2-N): acute danger to fish
Value too high – lower ⇓
Value too low – raise ⇑
⇓ • Partial water change with more aci-
dic water
• Add CO2
⇑ • sera pH-plus
⇓ • Partial water change
⇑ • sera kH-plus
⇓ • Partial water change
⇑ • Add sera calcium plus
⇓ • Partial water change with water of a
little less conductivity
⇑ • Add sera sea salt in small portions
until the correct value is achieved
⇓ • Partial water change
⇑ • Add sera sea salt in small portions
until the correct value is achieved
⇓ • Partial water change (check pH value)
• Avoid still water zones by providing
water currents (use a water pump)
• Add sera ammovec
• Check/clean the filter
• Reduce number of fish
• Feed sparingly
⇓ • Add sera ammovec
• Check the filter
• Feed sparingly
• Check whether a fish or another ani-
mal is missing
• Partial water change
• Remove cause
⇓ • Partial water change
• Repeat partial water change after
12 – 24 hours

19. 19
Regular maintenance: Checking the water
Parameter
When to check?
NO3
Nitrate
Weekly
Mg
Magnesium
Weekly
PO4
Phosphate
Weekly
Cu
Copper
Fresh water
Fish feeling unwell
O2
Oxygen
Every 2 weeks
Cl
Chlorine
Water change
New setup
Ideal parameter
Ideal: maximum 20 mg/l (ppm)
From 20 mg/l (ppm)
Above 100 mg/l (ppm)
About 1300 mg/l (ppm)
Max. 0.1 mg/l (ppm)
Ideal: below 0.05 mg/l (ppm)
Ideal: 0.0 mg/l (ppm) (any detectable
amount severely harms inver-
tebrates or can be fatal to them)
Above 1.0 mg/l (ppm): fatal for all
living beings in saltwater aquariums
Above 6 mg/l (ppm): sufficient oxy-
gen
Below 0.02 mg/l (ppm)
Value too high – lower ⇓
Value too low – raise ⇑
⇓ • Install a slow flux filter and use sera
siporax
• Use 1 liter (10 oz.) sera siporax per
each 100 liters (26 gal.) of water in
the biofilter, and activate with sera
ammovec
• Carry out frequent partial water
changes with water that is low in
nitrate
• Reduce number of fish if applicable
• Feed sparingly
• Use a protein skimmer
• Partial water change
⇓ • Partial water change
⇑ • Add sera magnesium plus
⇓ • Partial water change
• Add macro ornamental algae
• Feed sparingly
• Reduce number of fish
⇓ • Add sera aqumarin
• Generous partial water changes with
copper-free water, prepare fresh
water with a double dose sera aqu-
marin
⇑ • Rapid increase with sera oxypur
• Aerate water
• Find out and remove cause
⇓ • sera aqumarin neutralizes the effects
of chlorine
• Add sera chlorvec
• Add sera ammovec
• Aerate water well

20. 20
Regular maintenance
As well as monitoring the water parameters
and cleaning the filter, several further main-
tenance measures must be carried out on a
regular basis.
Removal of unwanted algae
If large macro ornamental algae, such as
Caulerpa, grow in your aquarium, you should
carefully control their growth. The rapidly
growing Caulerpa algae can actually over-
grow the invertebrates. Select and remove
the unwanted algae without taking too
many at one time.
Algae leaves are called “thalli.” They consist
of a single cell that releases its nitrate-con-
taining cell liquid into the aquarium if it is
not removed properly. The safest way to cut-
back your algae is to do this:
Look for the rhizome; this is the cord from
which the single thalli grow. On it, you will
see the fragile spots beside the thalli at
which the algae can be broken apart. Snip-
off the unwanted segment of the Caulerpa
algae, and immediately remove it from the
aquarium. Be careful not to damage the
algae as this will lead to cell liquid running
into the aquarium uncontrollably.
Change 5 – 10% of the water monthly, prepar-
ing the salt mixture in a bucket according to
the directions on page 12. This is also an
opportune time to use the sera gravel wash-
er to clean the aquarium gravel of debris and
detrimental micro-organisms – as we will see
in the following sections.
Waste removal
To avoid polluting the water, remove any
waste, such as dead algae parts, with the
sera gravel cleaner or a tweezers, instantly,
before it accumulates. Do not wait for sched-
uled water changes.
Water change

21. 21
Regular maintenance
R/O water for cleaning and
addition
In areas with high levels of nitrate and/or
phosphate in the tap water we strongly rec-
ommend purchasing an ion exchange or
reverse osmosis (R/O) unit. By purifying the
water this way, approximately 95% of the
dissolved pollutants are removed.
R/O water is much more suitable than tap
water for water changes and for replacing
evaporated water.
Tap water must be conditioned by using sera
aqumarin according to the instructions.
Open aquariums that are lighted with hang-
ing metal halide lights can lose several liters
of water through evaporation, every day.
This water must be replaced regularly, daily if
possible, with R/O water to prevent an
increase in salinity.
Lighting check
Fluorescent light tubes lose about 50% of
their light-emitting power after six months
use, whereas metal halide (HQI) lights have a
maximum “lifespan” of two years. As the
human eye does not detect the gradual
reduction of light, use the exposure light-
meter of a camera as an easy method of
monitoring this problem. Note: These tests
must be carried out from the same distance
and angle each time.
While you are on
a holiday
For short-term vacations
(up to 10 days), the animals
in your reef aquarium need
not be fed. Live rock pro-
vides the aquarium with
plenty of micro-fauna to
serve as a food supply.
During longer vacations, we
recommend setting-up a
maintenance plan to give to
the person caring for your
aquarium while you’re away.
Along with feeding instruc-
tions, this should include
information on topping-up
the tank with R/O water, and
providing trace elements
(sera marinvit plus) for the
invertebrates. Advise them
on the exact number of
food tablets (sera O-nip,
sera viformo, sera Spirulina
Tabs, sera Plankton Tabs), as
well as which days to do the
feeding. Tablets are the
preferable choice to leave,
as inexperienced aquarists
usually drastically overfeed
with flake and granulated
foods, causing severe water
pollution.
Camera with
exposure meter
Fix dis-
tance
and
angle
exactly
All settings
and conditions
must be the same
for each test

22. The ocean represents the most stable eco-
logical system on earth. Over millions of
years the ocean’s inhabitants have adapted
to the water’s constant physical and chemi-
cal changes, but as these parameters vary
only slightly in nature, the animals are much
less able to adapt than their freshwater
counterparts. Because of this – marine
aquariums must provide continuously stable
conditions.
The pH value describes whether the water is
acidic (pH below 7), neutral (pH = 7) or alka-
line (pH above 7). The pH value in natural salt-
water is slightly alkaline (pH 8 to 8.5).
In the aquarium the pH is lower in the morn-
ing than in the evening. This is because algae
consume carbon dioxide (CO2) during the
day, resulting in a rise in pH. As a result of the
consumption of carbonic acid, the pH value
rises during the day.
The carbonate hardness (KH) in the water
serves as a buffer. It is able to neutralize
acids and therefore absorbs fluctuations of
the pH value to a certain degree. To provide
a buffering effect that is strong enough for a
saltwater aquarium, the carbonate hardness
must not fall below 8°dKH.
Check the carbonate
hardness of the water
quickly and accurately
with the sera kH-Test.
Increasing the KH level
is easy and safe with
sera kH-plus.
The pH value of the
aquarium water should
also be checked regu-
larly with the sera pH-
Test.
Consider using
the sera pH me-
ter for precise
monitoring of the
pH value.
You can raise the
pH value with
sera pH-plus if
necessary.
22
The interaction of

23. 23
pH, carbon dioxide (CO2), and carbonate hardness (KH)
When aquariums are over-planted with
macro ornamental algae (Caulerpa, Halimeda
etc.) pH values can rise over 8.5 because of
the high CO2 demand.
The easiest and most natural method of low-
ering and stabilizing the pH value is by sup-
plying carbon dioxide to the water. Add
carbon dioxide according to the specific
aquarium requirements, simply and confi-
dently, with the sera CO2 fertilization system
and seramic CO2 control system.
The seramic CO2 control system is ideal for
the automatic control and regulation of the
pH value in your aquarium. Simply set the
desired pH value and let the seramic CO2
control system inject the precise amount of
carbon dioxide for stable conditions. This
highly effective CO2 control unit system also
shuts-off automatically when the correct pH
value has been reached.
Saltwater aquariums demand a considerable
amount of the CO2, which should not be
underestimated. Even if you do not continu-
ously supply the aquarium with CO2, we
strongly urge you to keep CO2 in stock. This
way, you can react immediately if the pH
value and the ammonia level become too
high (see sections “The nitrogen
cycle” and “Checking the wa-
ter”).

24. 24
From ammonium to nitrate:
Let’s have a closer look at the nitrogen cycle:
Organic waste products in the aquarium
result in nitrogen pollution of the water.
Among those waste products are excretions
of the fish, uneaten food, and rotting algae,
as well as dead animals.
Nitrogen occurs in the aquarium in different
forms. Nitrogen containing waste products
in the aquarium are excess protein, ammoni-
um and ammonia, nitrite, and nitrate.
The waste products mentioned contain pro-
teins, from which ammonium converted to
ammonia is formed via biological decompo-
sition. The ratio between relatively harmless
ammonium and toxic ammonia is deter-
mined by the pH value. The higher the pH
value, the more ammonia is formed. Since
the pH value in saltwater is always above 7,
the ammonium level must be checked fre-
quently.
Check the total concen-
tration of ammonium
and ammonia with the
sera ammonium/am-
monia-Test. The chart
included in the test kit
makes it easy to deter-
mine the level of free
ammonia by comparing
the measured value and
the pH value. If the con-
centration of free am-
monia is above 0.2 mg/l,
a partial water change must be done
immediately, and sera ammovec should be
added.
The next step in the nitrogen cycle is the bio-
logical conversion of ammonium into ammo-
nia, and then into nitrite by Nitrosomonas
bacteria. For this to happen the bacteria
need oxygen. Therefore, this is called an aer-
obic (with oxygen) process. Nitrite is highly
toxic to fish and invertebrates.
Increased ammonium, nitrite, or nitrate lev-
els result from mistakes or improper aquari-
um maintenance. Another cause could be an
insufficient surface area for useful bacteria
to colonize.
Check the nitrite level
of the aquarium water
with the sera nitrite-
Test. If the value ex-
ceeds 0.3 mg/l (ppm), a
partial water change is
necessary.
The useful bacteria in sera ammovec
process dead plant parts, food left-
overs, and fish waste from ammonia via
nitrite into non-toxic nitrate
Well balanced planting
lowers nitrate levels
Nitrate-free water

25. 25
The nitrogen cycle
Lower the ammonium and
nitrite levels with sera
ammovec. sera ammovec is a
biological product containing
nitrifying bacteria that breaks
down ammonium and nitrite.
Simply add the liquid to the
aquarium water according to
the product’s directions for
use.
The biological decomposition
of nitrite by Nitrobacter bacte-
ria leads to nitrate. Also, at this
stage the bacteria need oxygen to thrive.
Nitrosomonas and Nitrobacter bacteria live in
all the oxygen-rich zones of the aquarium,
which include the upper gravel layers, the fil-
ter, and the live rock surfaces. From this we
see that oxygen-rich water is important not
only for the fish and invertebrates, but at the
bacterial level as well.
Nitrate is considerably
less toxic than ammonia
and nitrite. Neverthe-
less it harms delicate
corals when in concen-
trations of 20 mg/l
(ppm) or higher, and it
promotes the growth
of unwanted thread
and slime algae.
Check the nitrate level
in the aquarium with
the sera nitrate-Test.
Nitrate breakdown can take place only in
oxygen-poor zones. There the bacteria take
oxygen from the nitrate. This is called an
anaerobic (without oxygen) process. This
final step produces harmless nitrogen gas
that escapes into the atmosphere. The bio-
logical breakdown of nitrate is achieved by a
slow flux filter with sera siporax.

26. 26
The calcium level
Calcareous algae, fish, and invertebrates
extract calcium from the saltwater to build-
up their skeleton. Natural saltwater contains
about 400 – 450 mg/l (ppm) calcium.
Saltwater that is prepared with sera sea salt
begins with the correct calcium concentra-
tion, but is nevertheless constantly lowered
by regular, necessary consumption.
The calcium level in
saltwater can easily and
safely be determined
by using the sera calci-
um-Test. If the level falls
below 400 mg/l (ppm),
the calcium concentra-
tion can be increased
with sera calcium plus.
Unlike kalkwasser, sera calcium
plus affects neither the pH
value nor the trace elements.

27. 27
Strontium and trace elements
The magnesium level in natural
saltwater is about 1300 mg/l
(ppm). Replenish consumed
magnesium according to a-
quarium requirements with
easy-to-dose sera magnesium
plus.
Use the sera magne-
sium-Test to monitor
the exact magnesium
level.
Saltwater that is freshly prepared with sera
sea salt contains all the trace elements that
are important for your marine life. Although
the level of these trace elements are very
low (example: manganese 0.2 µg/l [ppm],
gold 0.004 µg/l [ppm]), they are essential for
fish and invertebrates. Protein skimmers,
along with natural consumption, eventually
reduce the level of trace elements.
Stony corals and other invertebrates need
strontium, besides calcium, to build-up their
calcareous skeleton. Due to its comparative-
ly high concentration in salt-
water (8 mg/l [ppm]) strontium
is not regarded as a trace ele-
ment.
Regular addition of sera marin-
vit plus ensures the ideal sup-
ply of strontium for corals and
other invertebrates. It contains
all the trace elements, in the
biologically correct amounts,
that are necessary for keeping
and breeding ornamental
marine algae and inverte-
brates.

28. 28
What to do if a marine animal gets sick?
Invertebrates
With a good maintenance routine, inverte-
brates are rarely affected by disease.
Nevertheless, certain aspects should be
taken into account:
• If the water temperature exceeds 30°C
(86°F), the skeleton formation of stony
corals is disturbed. Furthermore, the sym-
biotic algae that live in the tissues of the
coral (Zooxanthellae) die and as a result the
coral also dies.
• Crustaceans regularly shed their skin. The
water must contain 400 – 450 mg/l (ppm)
calcium for building up a new shell. The
carbonate hardness must be between
8 – 10°dKH.
• If an invertebrate’s growth becomes stunt-
ed, despite the best possible maintenance
conditions, the animal should be examined
for external parasites. These parasites
could be miniscule and possibly come out
only at night.
Planarians are flat white or red worms of
approximately 5 mm (0.2 in.) in size. They can
harm anemones, corals and other verte-
brates with their excreted slime. These
worms can be siphoned-out of the aquarium
by means of a flexible tube. Sometimes it is
useful to place a strong flashlight above the
aquarium at night. Many planarians assem-
ble in the light and they are much easier to
remove. Watch invertebrates thoroughly
before buying them! Small, brownish-red,
oval spots are usually planarians.
Bristle worms (Polychaetes) are actually
carrion eaters, and will eventually nibble on
mushroom anemones and stony corals.
Furthermore, they tear their prey away from
them and, in doing so, often injure these
sessile (immobile) animals with their sharp
jaws. It is possible to attract Bristle worms
with fish meat and then catch and remove
them. As they are mainly active at night, this
procedure should be carried out in the dark.
Be careful: Do not touch these worms. The
bristles break off and may cause skin inflam-
mations!
Small bristle worms hide in the gravel during
daytime and can be removed by siphoning
off a larger quantity of the gravel (approx.
30 – 50%) and washing it with fresh water.
Usually, this is sufficient to remove these
Polychaetes from time to time.

29. 29
What to do if a marine animal gets sick?
Many snails nibble on sea anemones, corals,
and other invertebrates. In a reef aquarium
every snail should be carefully removed with
a pair of tweezers. Some snails feed exclu-
sively on sessile invertebrates.
Predatory shrimp species, for example mar-
bled shrimps (different Saron species), can
literally cut up anemones. These animals,
which are active at night, should be
siphoned off with a flexible tube or removed
with a pair of tweezers.
Parasitic diseases caused by micro-organ-
isms such as bacteria, or unicellular para-
sites, can only occur after preliminary dam-
age has been caused by a chemical, such as
ozone, hydrogen peroxide, or phosphate,
and they are almost never observed in well
maintained aquariums.
Combating these parasites with treatments
is impossible, as treatments, of course, can-
not differentiate between “desirable” and
“undesirable” invertebrates.
Fish
The best way to combat dis-
ease is by avoiding it, and the
danger of a disease outbreak is
greatly reduced by following
regular maintenance routines,
and by adding sera fishtamin
and sera activant vitamins to
your fish’s diet. If disease does
occur, sera has a line of sup-
port products that are safe and
reliable to use.
The most frequent and dis-
turbing diseases that affect
marine fish – and the recom-
mended care for your fish
while ill, are described below.
The parasitic Oodinium ocella-
tum (Velvet, or Coral Fish dis-
ease), in saltwater, attacks the
gills before migrating to the
skin – often leaving the fish
unable to pass sufficient oxy-
gen to breath. Copper-based
products, used carefully, such
as sera oodinopur have been
effective – although copper
must never be used in aquari-
ums with invertebrates. Apply
only in a quarantine tank.

30. 30
What to do if a marine animal gets sick?
The ciliate Cryptocarion irritans
resembles the freshwater par-
asite Ichthyophthirius (white
spot) and is therefore also
called “Saltwater Ich”. Use sera
cyprinopur according to the
instructions for symptoms of
white spots of up to 1 millime-
ter in diameter and strong
scraping movements of the
fish. sera cyprinopur is harmful
for some invertebrates (e.g.,
stony corals, snails, shrimp)
and for safety purposes should be applied
only in a quarantine tank.
Bacteria can cause many
noticeable symptoms in your
fish – among them, are skin
slime and fin rot. Use sera bak-
topur and sera baktopur
direct, according to directions,
at the first sign of symptoms.
As many invertebrates do
not tolerate treatments, we
recommend caring for your
fish in a quarantine aquari-
um.
Illness can considerably
weaken a fish. Once treat-
ments are complete, sera
fishtamin or sera activant
vitamins are ideal to help
support the animal’s im-
mune system while healing.
Use of treatments in the
aquarium cannot distin-
guish between good and
bad bacteria, and attacks
them all. After every treat-
ment, use sera ammovec,
according to directions, to
help regenerate the filter
bacteria colonies.
Use sera super carbon to remove the treat-
ments residue from
the water after treat-
ments.
Cleaner wrasses and
cleaner shrimps help
prevent the problem
by “preening” the
ectoparasite from
your fish. Also some
nettling coral species
(e.g., gorgonians) have
positive effects on
fish diseases.
The best disease prevention measures are
good, constant water conditions, varied
nutrition, and an appropriate vitamin supply.

31. 31
What you always wanted to know about saltwater
What is “kalkwasser?”
A saturated solution of calcium hydroxide in
water is called kalkwasser. This concentrated
alkaline solution raises the calcium level of
the water without raising the carbonate
hardness – it can, however, elevate the pH to
uncontrollably high values. In the past, kalk-
wasser was the most practicable method of
providing calcium but this is now considered
risky. sera calcium plus does not affect the
pH value and is therefore safer to use, mak-
ing kalkwasser an unnecessary part of your
maintenance routine.
What is a protein skimmer
good for?
A skimmer helps to reduce the aquarium
water pollution. Proteins attach to the air
bubbles produced by the skimmer, forming
solid foam. This foam is pushed upwards
within the foam tube, thus removing the
skimmed substances from the aquarium
water circuit.
What does a calcium
reactor do?
Many corals, mussels, and calcareous red
algae require dissolved calcium for their
growth. Using carbonic acid (dissolved CO2),
lime material is dissolved to form soluble cal-
cium compounds within the calcium reactor.
As this process takes place below pH values
of 6.5 – 7 only, a portion of the added car-
bonic acid is required to lower the pH value
within the reactor. The remaining portion is
then used to dissolve lime. The pH control
required for this is achieved by the seramic
CO2 control system.
What is “live rock?”
Live rocks are reef rock pieces that are
imported together with herbal and animal
periphyton organisms. It must be transport-
ed moist and tempered. In pet stores they
are kept like corals in aquariums. They will
bring many useful small organisms into your
aquarium and therefore promote natural
conditions. Speak with your specialty retailer
for more information on adding live rock to
your aquarium.