Lighting serves both a functional and an ornamental purpose when plants are part of the aquarium environment. Through the process of photosynthesis, plants increase the oxygen level essential for fish respiration and at the same time reduce the carbon dioxide level, preventing the buildup of carbonic acid which can be harmful to fish. Special plant grow lamps, that produce high emissions in the red and blue regions, are commonly used. Brilliant colors are observed in both the fish and plants when these special tubes are used.
Lighting for saltwater aquariums serves a functional purpose and produces a sea-like or natural environment for fish and invertebrates. Actinic Blue tubes that have a high emission peak at 420 nanometers are commonly used. This high-energy blue light penetrates to the bottom of the tank providing light for photosynthesis. Full spectrum or Daylight tubes are mixed with Actinic Blue tubes in an aquarium lighting system to simulate the sun, the natural source of light. The same affect can also be attained in a single lamp by mixing Actinic Blue phosphor with Daylight phosphors. By using the proper lighting, algae, fish, and invertebrates can thrive in a saltwater aquarium.