Introduction by P. Parson

Advantages of plants in the aquarium

	Production of oxygen.
	Use of carbon dioxide.
	Conversion of inorganic substances into organic.
	Providing food for vegetarian fishes
	Security for shy fish.
	Visual appeal.

To successfully grow and propagate aquatic and semi-aquatic plants in an aquarium we must know from what continent and ecological habitat our specimen comes. We can then set about recreating an environment suitable for the plant. Most of the plants used by the aquarium hobby come from tropical and sub-tropical areas, a few from temperate zones and even fewer from our local indigenous waterways. New Zealand has few native plants that adapt to either cold or tropical tanks.

Strangely, tropical soils are not particularly fertile. They are poorer in nutrients than most soils in more temperate countries. In many tropical climates there are extremes in flood cycles and plants go through wet and dry periods that are difficult to recreate in home aquaria. Instead, we must carefully prepare a medium in which to root our plants. Fortunately not all aquatic plants need a rooting medium as aquatic plants can absorb nutrients through their stems and leaves, while some like Elodea, Ceratophyllum, Myriophyllum, Eichhornia, and Hydrocharis float mid-water or on the surface, others are better grown in a bog situation (as is indicated in the individual plant copy here that follows in later pages).

A freshly set up tank needs time (three to six months) to reach a healthy balance for good plant growth. Start with coarse washed sand (3 to 4mm) and plant any of the varieties shown on page 3 that have sustainable food resources such as tubers, rhizomes, or bulbs. It will take some months before a good supply of plant food accumulates in the substrate from fish waste and decomposed plant matter to adequately supply those plants that feed from roots alone. A thin layer of trace elements, minerals and nutrients should be added at first to help plants become established and to speed the nutrition levels in the substrate. Add about a 50mm -70mm of 3 - 4mm sand and about 25mm of 2mm sand on top. Make sure there are no impurities such as limestone or metals etc. which can dissolve and react in the water to change the composition of the tank water.

Water circulation through the substrate can be achieved by placing a heat pad beneath the aquarium which will ensure an even heat throughout the substrate and water. Tiny convection currents will be formed by the heat rising from below, which will provide plant roots with nutrition. This is where care in choosing the size of the substrate (sand) pays off. If the substrate is too coarse an excess of nutrients will be released into the water, and if too fine, it may become airtight and become anaerobic and stagnant.

Filtration turnover should be a maximum of the tank volume once per hour. An internal, or external power filter containing a suitable sponge surface, should be used to aid the culture of aerobic bacteria - this will condition some nutrients and improve the water clarity. The filter medium should be split in two so that either half can be rinsed in tank water (from water changes) alternately once every two weeks. The returning water should be at least 60mm beneath the water surface so as not to aerate the system with oxygen. Oxygen is really what the plants are trying to get rid of. Under-gravel filters are not recommended because they culture aerobic bacteria in the substrate; also the flow of excess water rich in oxygen has a damaging effect on most plant roots - especially fine root systems.

The heat pad should be connected to a suitable thermostat to provide a temperature range of 22 -26 C. which suits most planted community aquariums.

Suitable Lighting

Lighting needs to run for a minimum of 12 hours per day, even in winter, and 14 hours per day during summer is more acceptable. Increasing the light intensity does not mean you can reduce the amount of hours per day as all plants, even shade loving plants, require a minimum of 12 hours light per day.

Metal Halide

These rate number one for aquarium lighting because of the intensity and spectrum, but a UV lens should be fitted. Bulbs should be replaced at about 12 monthly intervals. However they are expensive to purchase. The unit with bulbs should be suspended well above the water surface because they generate a lot of heat.

Mercury Vapour

Rate number two, because of their intensity but are not as full spectrum as metal halides.

Fluorescents

Are the most favoured lighting because of low heat output, low running costs and range of choice of tubes. High intensity, full spectrum tubes are recommended, some have a 7000+ hour lifetime. Domestic tubes suitable are: Balanced Daylight; Standard Daylight; Warm White, and White. Unfortunately their effective lifetime is only 8 to 12 months and they need replacing regularly.

Grolux

Grolux and the likes were not originally designed for submersed plant growth, only for emersed horticultural use. Subsequently, they concentrated their output in the red and blue areas of the spectrum - they lack the middle of the spectrum and also lack intensity.

Suitable hardness

A suitable hardness would be 80 -150 ppm; and a suitable pH would be 7.0. The more acid the water, the less nitrogen, phosphorus, sulphur, calcium, & magnesium will be available. However, more iron, manganese, boron, copper and zinc will be available. This is reversed if the water is alkaline.

General Comment

When first planting, aim to cover 70% of the aquarium, and add a couple of algae eating fish (Chinese algae eaters) for the first month to give the plants time to establish their root systems and use up the nutrients in the water, otherwise algae may overwhelm plants using the excessive nutrient in the system. Live bearing fishes will produce a much richer substrate in a shorter time than tetras.

Water changes

Water changes of 10- 15% per fortnight, siphoning mulm from the substrate surface is required; pruning should also be done at this stage. Plants coming from the Malaysian area are more exacting than those from the Amazon area because during the monsoon season, there is even flooding over very large areas with no water currents to break plants or to cover plants in sediment. This is the time most plants propagate in a vegetative manner while they are submersed.

Temperature

Temperatures are very stable at about 25 -27°C all year. During the summer dry season plants become emersed and subsequently change their propagation mode and begin to flower and propagate by seed. Most Cryptocorynes and Anubias come from these type of conditions. Plants coming from the Amazon area have a lot more tolerance for external changes. During their monsoon season, floods rushing into large rivers wash sediment, fallen trees, and other vegetation down river; plants become submersed and are damaged by fast river currents and sediment.
Temperatures may drop down to 14°c. At the other extreme during summer
rivers are very low, lagoons virtually dry up and plants become emersed. As flood levels begin to drop and river settle down submersed plants begin to flower. Echinodorus species grow well and amphibious plants start to grow.
During the dry season when water levels are at their lowest and temperatures at their highest (up to 40°C) submersed plants have finished flowering.
Echinodorus and amphibious plants are flowering and have maximum growth. As the rains begin again Echinodorus move into a vegetative propagation phase and floods wash down the small plantlets.