Can be used in saltwater and freshwater. This is the standard bulb that comes with the 6 gallon nano cube by JBJ in its hood and in replacemement hoods. The BLUE/WHITE COMBO/18W STRAIGHT PIN LINEAR PC bulb is a number one seller.
Note: Over time the blue spectrum fades in your bulb. Light bulbs should be replaced every 6 months to maintain optimum light levels for your fish and corals.