Metal halide - FYI

Metal halide (HQI or MH).
Lighting from MH differs significantly from fluorescent lighting. By comparison, it more intense because it is a ?point source? light, meaning all the irradiance of the light comes from a filament in a bulb rather than the entire length of the tube, in the case of fluorescent.

The result ? sharp crisp light not duplicated by any fluorescent lighting. Plus factor is the glitter lines in the aquarium. These are caused by the point source lighting striking ripples on the surface. The ripples can act like moving lenses and magnify the light dramatically, creating very natural looking patterns of rippling lines of shadow and brightness throughout the tank.

These flashes are ubiquitous in the nature, resulting from sunlight striking waves and ripples on the ocean surface. There are some research that suggests that the periodic amplification of light energy by the glitter lines is important in maintaining the health of light demanding corals, as it serves to punch light deep into the coral tissue containing the zooxanthellae.

The flashes typically amplify light energy by approximately 200% from 1 ? 4 times per second for about 0.1 of that same second. Therefore, for up to one half of each second, corals receive greatly amplified light energy. Glitter lines certainly appear on the reefs, and even if there is no benefit to them, they are very natural and attractive looking in the aquarium.

That is from the book titled Aquarium Corals by Eric Borneman. This is other side of the coin of MH qualitative benefits. The costs and benefits having MH have to be weighted. Hope this shared knowledge has cast brighter lights to your doubts.