Growing aquarium plants

Growing aquarium plants offers many challenges and benefits to the aquarist and fish.

By following a few guidelines, what used to be a matter for the ‘professional’ aquarist

is now within reach of every fishkeeper.A successful planted aquarium requires a

slightly different approach from traditional fishkeeping. In a planted aquarium,

the health and growth of the plants is the priority followed by the fish, which as

experience shows will benefit greatly themselves from a well-planted aquarium.

The requirements of a planted aquarium and how to provide them

Soft, acidic water (pH 6-7, KH 5)

Good light spectrum for plant growth

Still or very slow moving water

Additional CO2if possible

A readily available source of nutrients

Most tapwater is alkaline and buffered to prevent its pH from becoming

acidic. It is therefore unsuitable as a source of water for a planted aquarium.

Rainwater and water from a reverse osmosis unit are both ideal for the planted

aquarium but will require mixing with about 1/5th tapwater. Test the

pH and KH to check that it falls within the desired parameters.

Plants require light to as a source of energy for growth, requiring light in the

warm white to yellow end of the spectrum. Any light sources that contain too much

blue light are undesirable as they will promote algae growth.

Suitable lighting can be provided using a combination of tubes such as Sun-glo,

Flora-glo and Freshwater tubes. The preferred lighting for excellent plant growth

are mercury vapour lamps as they offer a superb spectrum and depth penetration.

These are hung over the aquarium which is installed without a hood.

Too much light each day can encourage algae-growth so a useful way of giving the

plants 12 hours of light each day and still enjoy the aquarium in the evening is to

illuminate the aquarium twice each day (7.00am – 12.00 noon and 4.00pm – 11.oopm).

If algae begins to appear then respond by reducing the length of illumination each day.

Still or very slow moving water ensures that the surface of the water is not agitated.

This helps to retain any CO2 within the water, helping plant growth.

For this reason, the best form of filtration in a planted aquarium is an external

power filter that can remove and return water in a non-turbulent fashion. As the

filter matures biologically, it will also give off more CO2, enhancing

plant growth further approximately 3-4 months after setting up.

NB. Under no circumstances should airstone or air pumps be used in a planted aquarium

as this encourages algal growth and vents off any residual CO2 in the water

to the atmosphere.

Plants require CO2 to produce sugars which are used for growth.

The more CO2, the more growth. Planted aquaria will flourish if

additional CO2 is added to the aquarium, over and above that produced by

fish, bacteria and plants themselves.

CO2 cylinders are available (Soda-Stream will do) and will bubble in

CO2 for many months. The gas is bubbled in through a ‘reactor’ which is

connected to the venturi pipe of an external filter. Planted aquaria without a

regular, reliable CO2 supply do not flourish as well as those with

additional being added.

Besides CO2, plants also require a range of minerals for healthy

growth. These must be provided in two ways:

a. An iron-rich clay mixed with an inert (quartz gravel/sand) substrate. As the

substrate matures and organic acids develop, they react with the iron clay to

form a soluble form of this vital nutrient which is taken up by plants and used

to make the green pigment, chlorophyll.

A form of undergravel heating will encourage these minerals to rise out of the

gravel enhancing plant growth further.

b. Trace elements. These are best added in liquid form on a weekly basis.

Final Tips

When planting the aquarium, plant lots of faster growing plants that will fill

spaces quickly, competing with undesirable algae. As the slower-growing specimen

plants begin to emerge, the pioneer plants can be removed to make space for the

preferred plants.

Once the plants have really started to grow (and bubbles of oxygen can be seen rising

from the plants) fish can be added a few at a time. Check that the CO2

entering the tank is not too excessive to cause fish to gasp. The first fish to be

added should be algae eating fish as algae is likely to flourish in the first few

weeks. On a weekly basis, check that the pH and KH are within the desirable limits.

Kill blanketweed and string algae.