Arcadia T8 Marine Blue 420nm Actinic lamps re-create the effect of a moonlit ocean and brings out the natural fluorescence in corals. The Marine Blue Lamp peaks at 420nm the optimum point in the spectrum for marine fluorescence. This range has been created to provide the specific spectrum (400 – 480nm) necessary to achieve the blue chlorophyll absorption for zooxanthellae symbiosis to develop. This concentration of light energy in the so called “actinic” range peaking at 420nm is essential for the survival and good health of fish corals and invertebrates in marine aquariums. The UV output present in the Marine Blue range creates a very pleasant fluorescent effect on corals invertebrates and exotic marine fish. When used at night with no other lamps the effect is of a dark moonlit night with the vivid colours of the corals and invertebrates fluorescing brilliantly.