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Dupla's Golden Rules


  1. [F] Good plant tank advice
    by (George Booth) (8 Nov 1994)

[F] Good plant tank advice

by (George Booth)
Date: 8 Nov 1994
Newsgroup: rec.aquaria,alt.aquaria,sci.aquaria

The following was scanned in with permission of the Dupla importer. 
It is from a product brochure and details the reasoning behind the
"10 Golden Rules" of Optimum Aquariums.  I have "sanitized" it in 
an effort to abide by the Usenet "no advertising" conventions.  
Product names were changed to generic terms to protect the naive 


The aquarium is an artificial habitat for tropical fish and plants.
Even the largest aquarium is very small in comparison with the natural
biotope.  Without appropriate regulation the chemical and physical
conditions in it will very quickly go from one extreme to another.
Thus fish and plant life in the aquarium is not possible without
corresponding control by the aquarium operator.

Building upon the decades of experience of Horst Kipper and Kaspar
Horst, Dupla today has a large personnel force working on the
perfection of the aquarium, an optimum aquarium which permanently
offers fish and plants good habitat conditions, partially even better
than in nature.  The basis was formed by countless biotope
investigations in the native countries of aquarium fish and plants.
The findings gained have been transformed into practical aquarium
terms by means of numerous tests and extensive development work.
Simultaneously, the rules for a successful aquarium have crystallized
out of this work. Dupla summarized them in the "10 Golden Rules for
the Optimum Aquarium".  These form the basis for the Dupla aquaristics


The 10 Golden Rules for maintalning an optimum aquarium provide the
rules for a well functioning aquarium in which fish and plants are
able to lead a healthy, vigorous life. They remove the factor of
uncertainty trom the aquarium from the very beginning and render it
independent of chance occurances. With its aquaristics systems Dupla
provides high-quality appliances and products by means ol which the
"Optimum Aquarium" is realizable and reproduceable. The following
pages provide the modules step by step which you require in order to
reach this target.

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The heating system (a low-voltage bed heating system) influences life
in the aquarium very decisively: the heating cable (on the bed of the
aquarium) integrates the entire bed soil into the chemical and
physical cycle of the aquarium by means of the upward current of water
caused by it. This ideal aquarium heating system fulfills several
requirements simultaneously:

1. The same temperature in the water and in the bed, just as in
natural waters. (If the aquarium water is heated up e. g. by means of
heating bars, only the water becomes tropically warm, while the bed
soil remains at room temperature and the plants notoriously suffer
from "cold feet").

2. Bed water currents which prevail in natural waters are copied;
nutrients are fed to the roots, the materials discharged by the roots
are carried away.

3. A stable redox potential in the bed. The bed is prevented from
turning black and an optimum stock of iron is supplied to the plants,
as in tropical waters in conjunction with laterite (see section 4 -
"Plant Nutrition in Accordance With Nature").

4. Absolute safety for man and fish, even if the heating cable is

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The lighting system exclusively comprises lighting fittings which
reproduce the natural light in fishes' and plants' natural biotope
both in fresh water and in sea water in an excellent manner. They thus
fulfill the two important functions of light:
a) to put the underwater world in the right light setting and

b) to supply the necessary energy for plant growth.


1. Light's most important function is to provide the aquarium plants
with sufficient energy for optimum metabolism; amongst other things
the assimilation of nutrients incl. CO2 and the discharge of oxygen to
the water. In the aquarium this is also easy to check by measurement
of the oxygen with a test kit. Towards evening 100% oxygen saturation
should be achieved.

2. The light day under water is shorter in tropical waters than the
light day above water.  This is a consequence of the angle of
retraction in the water. The sunrays do not penetrate the water until
they are at a certain height above the horizon. Thus the light day
under water amounts to approx. 8 to 10 hours. The consequence for the
aquarium: strong light but a shorter period of illumination.  Even 14
hours do not bring about 100% oxygen saturation!

3. Many plants which are used in the aquarium as foreground plants,
e.g. echinodorus tenellus. Iilaeopsis novazelandiae etc.. grow on
embankments and receive the most light there. If the lighting is weak
though, they will obtain too little light in the aquarium, assimilate
only inadequately and rot.

4. A good lighting system offers with its adequate lightings
the ideal light for the different requirements in the aquarium.

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Tropical waters, especially flowing waters, have a surprising degree
of stability independent of the season, water level and light
conditions.  Factors such as the pH-value, the CO2 content, degree of
hardness etc. have only a slight fluctuation range.  Several functions
are also dealt with simultaneously by an automated CO2 system, which
assures stability in the aquarium:

1. Constant pH-value 

In the optimum community aquarium in which tropical fish from
geographically and chemically different waters can be cared for, a
neutral pH-value setting is recommended. Both fish from weakly acidic
waters (e.g. neon fish) and also those from slightly alkaline waters
(e.g. Lake Malawi or Lake Tanganyika) find an optimum tolerance range
here. The CO2 system also offers great advantages for specialized
aquariums in which special fish species, e.g. discus fish, can be
cared for or bred. Due to the precisely determined CO2 dosage with a
controller, both acid and alkaline pH ranges are able to be programmed
and set so as to be stable.
2. Stable carbonate hardness

If an aquarium suffers from CO2 deficiency, the following sequence
will occur. Carbon is chemically bound in the carbonates. Now the
plants need this carbon. since a different source is not available.
In this process, so-called biogenic decalcification, carbonates are
destroyed. As a consequence the carbonate hardness drops to
dangerously low values and the pH-value becomes extremely unstable.
However, with sufficient CO2 supply the plants utilize the carbon
contained in the carbon dioxide. Biogenic decalcification no longer
occurs and the stability of the water is assured.
3. Optimum carbon supply

Submerged water plants meet their carbon requirements preferably from
gaseous, solute carbon dioxide in the water. The supply from
carbonates. which is also possible, leads as described above, to
greater problems.  Optimum carbon supply is assured by CO2

This table will assist in determining the exact requirements of any
given aquarium, particularly in respect of CO2 fertilization. It
confirms the rule that optimum pH regulation by means of CO2 diffusion
leads to the optimum availability of carbon for the plants. It also
highlights the exceptions to this rule, however, in that water
containing a carbonate hardness of less than 3 to 4 degrees can suffer
a shortage of CO2 very quickly. In fact at neutral pH-levels the CO2
content is already very low! In the case of a carbonate hardness less
than 3 to 4 degrees the pH-value should be decreased to 6.4.  Under
these conditions even a good CO2 test can show misleading results if
the carbonate hardness is less than 3.5 degrees due to the presence of
humic acids, high nitrate values, and other substances that "fool" the
test into thinking that CO2 is present.

[ Note: the following table is from a posting by Pauli Hopea of the
  Helsinki Aquarium Society, not from Dupla. ]

KH \ pH | 6.0     6.2     6.4     6.6     6.8    7.0    7.2    7.4    8.0
0.5     | 15      9.3    *5.9    *3.7     2.4    1.5    0.9    0.6    0.2
1.0     | 30      19     *12     *7      *5      3      1.9    1.2    0.3
1.5     | 44      28      18     *11     *7      4      2.8    1.8    0.4
2.0     | 59      37      24     *15     *9     *6      4      2.4    0.6
2.5     | 73      46      30      19     *12    *7      5      3      0.7
3.0     | 87      56      35      22     *14    *9      6      4      0.9
3.5     | 103     65      41      26     *16    *10    *7      4      1.0
4.0     | 118     75      47      30      19    *12    *6      5      1.2
5.0     | 147     93      59      37      23    *15    *9      6      1.5
6.0     | 177     112     71      45      28    *18    *11    *7      1.8
8.0     | 240     149     94      59      37    *24    *15    *9      2.4
10      | 300     186     118     74      47    *30    *19    *12     3
15      | 440     280     176     111     70     44    *28    *18     4
20      | 590     370     240     148     94     59    *37    *24     6
        |                  CO2  milligrams/liter 
             * 5 to 20 mg/l is a good level for most KH ranges

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Contrary to tropical plant waters, our tap-water has large nutrient
deficiencies. Many important plant nutrients and trace elements are
missing or extracted from the water during treatment at the
waterworks. However, if a nutrient is missing, even if only
temporarily, the plants' growth will be stunted or the plants perish
(Liebigs's Law Of Minimums). In order to ensure healthy plant growth
in the aquarium, the nutrient deficiencies in the tap-water have to be
stocked up and supplemented, so that good "aquarium water" is derived
from tap-water. For this purpose it is decisive that the nutrients are
in a very certain ratio to one another. Several "critical nutrients",
in particular iron and a series of trace elements, present special
problems in solving this task; they are required in only minute
quantities.  In larger doses their effect is poisonous. In aquariums
they may not be administered for days and weeks in advance, e.g. if
the water is changed. The situation is rendered more serious if
various trace elements are not only being consumed by the plants but
also being precipitated by chemical reactions. This has always
presented plant fertilization in the aquarium with special problems.

Commercially avaialble laterite consists of selected tropical laterite
with a high iron content. This laterite conditions the bed soil in the
aquarium just as it is encountered in tropical plant waters.

Laterite granules are added to the bed material when the aquarium is
initially set up. A root activation tablet (N and P) is enclosed in
the laterite pack for the purpose of rapid root formation.
Compacted laterite balls are used for retreatment of the bed soil in
the aquarium.

Basic fertilizers should contain all important plant nutrients which
are missing from tap-water; in addition all trace elements which
remain available in the aquarium for a short time. Important: Basic
fertilizer is dosed in accordance with the total volume when the
aquarium is initially set up; when the water is changed only in
accordance with the proportion of fresh water.


It is extremely important for the growth of aquarium plants that
fertilization is not performed so as to provide reserve stocks, but
only in low daily quantities. All oxidizable trace elements and iron
are bound by means of chelation and are thus soluble over a long
period of time. Important: The need for nutrients in the aquarium is
dependent on the plant quantity, lighting and other factors. A
repeated check on requirements is therefore recommended by measurement
of the iron with a good iron test kit (maintain ~0.1 ppm Fe in the

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Aquariums are fundamentally over-populated with fish relative to their
water volume. Metabolic productc from fish, but also from snails,
plants and other sources build up and contaminate the water. The
aquarium owner counters this process by changing the water regularly
and by means of suitable filtration. Purely mechanical filtration by
means of cotton wool, carbon. clay tubes etc. is being replaced more
and more by "biological" filtration. "Biological" means: filtration
by means of a medium colonized by bacteria which remove all materials
contaminating the water and thus assure cleaning of the aquarium
water. Specific bacteria are also able to even regulate the remains of
chelate compounds and over-fertilized chelated. Industrial discharge
water techniques also make extensive use of this filtering technique.
Regeneration of the contaminated water is possible up to the point of
drinking-water quality.

The bio-ball has been especially developed for the trickle filter
system. This concerns an ingenious plastic framework with a
particularly large surface. It is so designed that extensive bacterial
colonies are able to form on without the filter surface closing up and
becoming smaller. as does happen with fine textured filter elements.
The bio-ball is deployed principally in trickle filters.  Filter
volume 2-5% of the aquarium water. If a suitable pre-filter is
utilized, which is cleaned regularly. The bio-ball filter is able to
function continuously as an "eternal filter" without maintenance.
Bacteria colonies which have grown excessively, break off and are
flushed away. The filter is self cleaning.

Filter media for biological filtration. The mini bio-ball has been
especially developed for the use in closed filter systems, e.g.
circulation filter. It has an extremely large surface of 3900 mm2, and
due to its small dimension and the optimum space utilization, the
mini bio-ball provides full efficiency in small filter systems as well.

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Good to strong water movements are the following reasons:

1. Water movement having an effect from the surface of the water down
to the bed soil will assure even temperatures in all zones of the

2. Only a strong movement of water will manage to carry away organic
waste materials Iying on the surface of large sized plant leaves, 
e.g.  Echinodorus, Cryptocorynen, Anubias etc. If there is excessively
weak water movement, adhesion forces firmly hold a stable film of
water on the leaves' surface, thus hindering interchange processes or
even eliminating them altogether.

3. Water zones with fresh nutrients reach the leaves' surfaces by
means of water movement.

4. Provide a strong current for the fish. Many fish need this,
especially those coming from rapid flowing streams.

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The optimum aquarium is dependent on dense and well growing plants.
The advantages of a well planted aquarium are:

- Decorative overall impression.

- The substrate is kept in shape by the roots.  Oxygen is released by
  the roots to all areas of the substrate.  This prevents the substrate 
  from turning black.

- Well growing plants provide optimum oxygenation.

- Well growing plants are an excellent protection against algae of all

- Well growing plants inhibit disease causing organisms.

- Well growing plants remove toxic elements from the water.

- Several aquarium plants release antibiotic-like substances in the

- Dense planting provides good hiding and spawning places.

1. Use pre-cultivated plants adjusted to aquarium conditions.

2. The aquarium must be densely planted from the very beginning.  Use
many different types of plants that grow slowly, stay small and grow
offshoots. Tall growing plants that float on the surface must be
regularly trimmed back to prevent them from cutting out the light to
the plants underneath. Plants should not really get taller than the

3. All growth factors must be met. See Rules 1, 2, 3 and 4.

l. Plant densely with fastgrowing plants upon initial.  The greatest
algae danger exists during an aquarium's initial phase. Fast growing 
plants overcome this phase best of all due to the aquarium' s better
oxygen supply. Later they can be partially replaced by slower growing
plants, e.g. Cryptocorynen, Anubias etc.

2. Right from the start deployment of algae-eating fish:
Epalzeorhynchus siamensis (against barb algae, brush algae and green
algae). Otocinclus vittatus, O.alfinis.  Poecilia shenops, Plecostomus
punctatus, Barbus conconius, Farlowella acus etc.

3. Continuity of all conditions: Good lighting, neutral and constant
pH-value (6.8-7.2), permanent availability of all plant nutrients,
continous CO2 supply.

4. Correct bed soil: Quartz gravel, 2-3 mm grain, the bottom third
being mixed with laterite.

5. No nitrates, no phosphate content = excellent algae climate.
Prevention: water change, dense vegetation, possibly desalinate.

6. Use only precultivated plants. Be careful with directly imported
plants. The spores of tropical algae can be introduced by this means.

7. Be careful when adding or replacing fish or plants from other
aquarium' s! Algae spores can very easily be undesirably transferred
by this means, and will possibly "explode" in the new aquarium due to 
better habitat conditions.

8. Do not use any decorative materials containing calcium: Stones,
gravel etc.  Calcium sample: Test gravel using hydrochloric acid. If
it contains calcium, the gravel will foam.

9. No prevention by means of algicides (algae control agents). This
harms the plants more than the algae.

10.Don't put transportation water into the aquarium. When adding new
fish and plants the transportation water should not be put into the
aquarium. Insert fish using a net.

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A balanced fish population goes hand in hand with the idea of
providing both fish and plants with an environment that is optimally
designed. In the optimum aquarium fish and plants should be a
harmonious combination.

Here are some basic rules:

- Do not mix fish that are incompatible.

- Do not add fish that eat plants.

- Make sure you introduce algae eating fish right from the start, see
  also "Algae prophylaxis".

- Make sure the fish you put in all have the same temperature
  requirements, usually 25 to 26C (76-78F).

- To prevent an excessive snail population, a snail eater may be

- Choose fish that occupy all levels of the aquarium: Bottom, top and
  mid level.

- Do not add picky eaters if you are not sure that you will be able to
  provide them with the food thev need.

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Good food is a modern feed concept for aquarium fish. It was developed
in many years of research and trial work together with the leading
scientists.  One type of food is a granulate in various sizes; a
suitable type for any fish and mouth size. In addition food is
supplied with specific recipes as extremely fine feed and as tablets.

The main advantages of good food: 

1. Good food is free from colorants. For this reason it is
particularly easy to digest and is wholesome. It consists of valuable
raw materials which promote the health of aquarium fish by means of
their balanced composition.

2. Good food is fish-mouth sized and adapted to fish's eating habits.
Fish are piecemeal eaters, and because their mouths differ, good food
is supplied in various sizes of granulate between 0,25 and 1.6 mm.

3. Good food is a 3 stage feed, for, it is capable of floating, being
kept in suspension and sinking. By this means surface feeders, fish in
the middle zone and also bed feeding fish equally all obtain fresh and
full-value nutrition.

4. Good food  is stable in water. It soaks up water slowly without
losing its shape or disintegrating in doing so. The valuable content
materials are retained and are not leached.  Thus the aquarium fish
constantly get high-quality feed.

5. Good food is produced in the expansion process. The carefully
selected tropical microalgae, vitamins, proteins, trace elements etc.
are fully retained by means of this particularly gentle process.

6. Good food is packed in tins which are sealed tight against vapor.
In this way good food remains fresh and maintains a long shelf-life,
without loss of quality. This is one of the prerequisites for the
freshness guarantee provided by good companies.

7. Good food is ideal for dosing.  A new way of feeding aquarium fish
has been introduced with the dosing device which was specially
developed for granulate foods. The dosing device allows objective,
precise and hygienic feeding without losses.

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Preventing aquarium conditions from getting out of control unnoticed,
through the regular testing of, for example. temperature, pH, nitrite
content, iron content, carbonate hardness, and other factors. Compared
to natural waters, an aquarium is a very small mass of water. Test
values can go from one extreme to another over very short periods of
time. We, however, require a high degree of stability and continuity.
For this reason companies have developed analytical systems that serve
both diagnostic and therapeutic functions.
George Booth                         "Nothing in the world is more dangerous             than sincere ignorance and conscientious 
Freshwater Plant Tank Technology     stupidity" - Martin Luther King, Jr. 

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