Beginner Must Know - Aquarium Lighting

Aquatic Plant Lighting

Illumination For Aquarium Plants

Illumination is necessary for the planted aquarium. Without it photosynthesis cannot occur and aquatic plants will die after carbohydrate stores have been consumed. Lighting is required to have the correct colour spectrum to be of use for aquarium plants.

Sunlight contains the full spectrum of colour and would at first seem the best choice. However this method of aquarium lighting has notable disadvantages. The indirect light source is often too weak or short for plant functioning. The sunlight may also cause significant temperature fluctuations which will affect both fish and plants with stress.

Artificial lighting selected thoughtfully will provide the full range of required illumination. Today's metal halide lights and fluorescents can both offer aquarium plants the illumination required.

Although metal halide lights achieve excellent plant growth, they have notable disadvantages. Fluorescent lights are more practical because of reduced heat output, increased power savings and the lower initial purchase cost.

For optimal plant growth the tubes in a fluro light should be replaced every six months. The tube may look bright but unperceivable spectrum shifts will occur as the fluorescent tube ages.

Choose fluorescent tubes based on the manufacturer's lighting output descriptions. Most manufacturers will make a bulb suitable for aquarium plants. They are usually cheaper to buy at a large hardware store rather than a pet shop.

A tube rated as 'daylight' will offer a wide colour spectrum and more natural colours for the human eye. Unfortunately these do not provide as much of the best light wavelengths for plants. Dedicated plant growth tubes and the T8 fluorescent globes can often have an unnatural looking purplish colour. They do however offer plants more light in the spectrum that they can use.

You can have the best of both worlds. By combining both a specific plant tube and daylight balanced fluorescent tube you can have lush foliage and natural colours.

The length of light provided should be adjusted to minimise algae growth. Too many hours of illumination in a day will allow algae to flourish. Start at around 10 hours per day and gradually increase or decrease the length until the optimal allocation of light and dark is achieved.