When a fluorescent tube is lit it is emitting rays of light from all points around its circumference when the tube in question is over an aquarium any rays emitted from the top half of the tube are directed away from the water and are wasted by using a suitable reflector behind the tube it is possible to obtain the maximum efficiency from the tube because this otherwise lost light energy is re directed to where it is required into the aquariumr all arcadia reflectors are manufactured