Planted Aquarium Lighting

One of the most important requirements for freshwater planted aquariums is the selection of lighting. As a general rule of thumb, 4-6 watts per gallon is recommended for vigorous plant growth.

Light intensity and PAR, Photosynthetically Active Radiation, are more accurate indicators of the amount of light needed for plant growth in freshwater aquariums. Tank depth is an important factor to consider when choosing your aquarium lighting. The deeper the aquarium is then the more intense lighting system you will need.

Freshwater Light Spectrum

It is important to get bulbs with the correct spectrum for freshwater plants. Light emitted within the spectrum of 5500K-6500K is most like natural sunlight and will be of the most benefit to the plants. Look for aquarium bulbs specifically labeled for plant use or labeled as daylight spectrum.

Freshwater Lighting Systems

  • Power Compacts - Power compacts are best suited for small and shallow aquariums and loose their effectiveness at depths greater than 16"
  • VHO - Very high output fluorescents are a good option for 48" long aquariums such as standard 55 and 75 gallon aquariums. Ventilation will be important as VHO bulbs can produce some heat.
  • T5 HO - T5 High Output is able to provide a greater light intensity than other standard fluorescents or VHO bulbs while producing less heat. T5 HO bulbs are also thinner allowing more bulbs to be placed over the aquarium.
  • Metal Halides - Metal halide bulbs are the most powerful option and offer the most lumen-per-watt as compared to other types of aquarium lighting. Metal halides also offer the greatest ability to penetrate greater water depths. The downsides to metal halides are the amount of heat generated and the equipment expense.