MH lighting ?

[crazyseany]

I should probably already know the answer to this but.....Do you need supplemental lighting with metal halides?

I'm thinking of setting up a basic 20 gallon tank and if I can find a deal on an electronic 175w ballast.

I want basic... what would be the mininum # of hours the light would have to be on?

thanks
sean

 

[serpentman]

Long story short, provided the wattage matches the water depth, metal halides in and of themselves offer enough light to grow corals and do not require supplemental light.

Supplementation really has more to do with what color you are looking for. Lower spectrum bulbs such as 6500K or 10000K tend to yield more growth but also have a yellow tint to them and often require actinics to add more blue hues. 14000K and 20000K bulbs often promote more color and are bluer in hue but don't offer quite the amount of growth. Most use them without supplemental lights.