Artificial light is a lot the much better simply because you I can control the quantity of light required to stimu-1 late the plants, and to some extent stop the excessive growth of algae.
The quantity of light required per day for an aquarium measuring 24 in. x 12 in. x 12 in., assuming the quantity of daylight reaching the tank is negligible, is 50 watts for 9 hours.
It should be remembered that whilst extremely decorative effects could be obtained by varying the position of the lamps, the source of light should be above the tank to ensure that the rays enter the water in a natural way.
We know that plants should have light if they ( are to be healthy, so to give them the maximum benefit from artificial lighting, arrange the light source as near to the surface as feasible, but take care not to scorch the leaves of tall plants that spread their leaves along the surface.
Fluorescent lighting, which is the subject of a lot controversy, is, in my encounter, practically useless, as the coating on the inside of the tube absorbs most of the infra-red rays.
Aquariums covered with a sheet of glass could be illuminated with a light box, in which one or two lamps are mounted in sockets and stood open side down on the glass. The box should be well ventilated as excessive heat considerably shortens the life of the lamp, and cracks the glass cover. Strip lights in their reflectors could be stood directly on the glass if distance pieces are fixed to every end of the reflector to permit totally free passage of air around the lamp. The very best technique would be to combine the lighting with a top cover, which screens all extraneous light beams, and illuminates the interior uniformly.