Both the spectrum and intensity of the lighting required for your particular aquarium will be determined by the size of your tank and the type of tank inhabitants. When you are selecting the lighting for your freshwater aquarium you need to consider the spectrum as well as the intensity of the lighting. The higher the wattage of a bulb, the more intense the light it produces – higher wattages also require more energy to produce light. The intensity of a light bulb can be measured either in lux or watts – wattage is the more commonly used measurement of the two. When researching aquarium lighting you are likely to come across the term “intensity”. Bulbs that are labeled “color-enhancing” typically produce light from the warmer end of the spectrum and they too can be used in either freshwater or saltwater tanks. You may have also seen the term 50/50 or actinic white used – these terms are used to describe bulbs that produce a blend of white and blue light which is ideal for encouraging photosynthetic coral growth. This type of lighting is good for all types of aquariums, both freshwater and saltwater. Full-spectrum bulbs, or daylight bulbs, produce light from all wavelengths of visible light which produces an effect similar to that of natural daylight. Actinic bulbs produce light from the blue end of the spectrum – this type of lighting is recommended for saltwater reef tanks because blue light is able to penetrate deep water better than regular white light. You probably saw words like “actinic” or “daylight” accompanied by a Kelvin rating (measured in degrees Kelvin). If you have ever spent much time in the aquarium lighting section at your local pet store, you have probably noticed the way bulbs are labeled.

Goldfish aquarium lighting