Tropical Planted Aquarium Lighting Introduction

With a wealth of information available within the public domain, much of which is often conflicting, creating a successful and algae free planted aquarium can sometimes seem challenging and a little daunting. In fact, setting out and maintaining a beautiful aquascape is within everyone’s grasp; all that is required is a little dedication and a love of the hobby.

Over the following months we will be dealing with different aspects of the planted tank in order to make this fantastic art form more accessible. Subjects covered will include lighting, CO2, substrates, water, compositional rules, algae: its causes and prevention, layout, fertilisation and maintenance.

Light levels

We start this month with lighting. Light is the most important factor in growing plants, and as such it is an important foundation for a planted tank: get it right and you will find it much easier to achieve your goal, get it wrong and it will hinder your efforts and may be the cause of problems. Without sufficient light, growth will be sparse and leggy, with too much light nuisance algae blooms may be caused.

Many good quality professional plant catalogues such as those produced by Tropica will give a thorough guide to the lighting requirements of each species and prove to be an invaluable source of reference.

With the aid of a catalogue such as this, plants may be short-listed prior to use according to their suitability and lighting needs.

The first thing to note is that different species of plants will require different intensities of light; some such as Glossostigma elatinoides require very high light levels whilst others such as Cryptocoryne and Microsorum species will survive and flourish very well at lower intensities. Therefore it is necessary to consider what plants you would like in your aquarium before purchasing a lighting system, or conversely if you already have a lighting system, to choose plants that are suited to that system.

In addition to this, it is important to remember that in their natural environment tropical plants are often shaded by a dense jungle canopy and although a day in the tropics is often 12-hours long the mornings and evenings may be very dark and overcast and the plants may only receive direct sunlight from an overhead source for an hour or so each side of noon. We are simply striving to recreate these conditions within the planted aquaria.

Light research

Recent studies by ourselves and others have shown that excellent results are available across the board in most aquaria with the use of just two T5 tubes with an initial photo period (lights on) of just seven hours per day, rising to no more than nine hours after the aquarium has been established for several weeks ,the root systems have developed and the plants are established. We would go so far as to say that no aquaria need be lit for more than nine hours in any one day. This will not only save power, but will also help in the prevention of algae.

In a situation where the plants used are more demanding and need more light, a four tube T5 unit, a metal halide, or a combination of the two would be a good option. Even with this more powerful lighting we would only recommend that the units are run at full power for a maximum of three to four hours in the middle of the light cycle. As a rough guide, for example, an established tank with a metal halide light with two backup T5 tubes would be lit as follows;
• 9am until 12-noon, two T5’s only
• 12-noon until 3pm metal halide and T5 tubes together
• 3pm until 6pm, two T5’s only

In the first few weeks of planting, however, this tank would simply be lit with the two T5 tubes for six to seven hours per day until growth was noticeably improving or the plants themselves showed signs that they needed more light.

Kelvin rating

It should also be remembered that lighting of a suitable colour temperature is of importance. There is no reason to complicate this with science, it is sufficient to know that ideally this should be around the 5,000 to 7,000 kelvin rating. This applies to both fluorescent tubes and metal halide bulbs which should, (unless the tank is very deep indeed) be no more than 150-watts in power.

A cheaper option than T5 and metal halide lighting is to use the older T8 fluorescent lighting.

This can also be very effective and we have seen red coloured plants such as Rotala wallichii, which can be quite demanding in terms of light thrive when lit by three of these tubes. When using fluorescents, whether they’re T5 or T8, it is imperative to use a good quality reflector with the tube. This may cost a little more initially but is, without doubt, the cheapest way of upgrading your lighting efficiency within the tank. The results will speak for themselves and without a reflector you are both wasting power and depriving your plants of the energy that they need.

Summary

To summarise, the following relevant points should be borne in mind;
• Choose your plants carefully according to whether they require high or low levels of light, and a lighting system that satisfies their requirements. A professional plant catalogue is a great help.
• Do not be tempted to use very high levels of lighting.
• Do not exceed a photo period of more than nine hours per day.
• A new tank will need less light than an established tank.
• Use lighting rated at around 5000 to 7000 Kelvin.
• T8 tubes are a cost efficient option and perform very well when designed for plant growth.
• Always use reflectors with fluorescent tubes and replace tubes after the recommended burn times.