Metal Halide questions for new setup

[GSerg2]

Questions...

1. What spectrum MH bulbs would I need in order to eliminate the need for supplemental VHO's?

2. How far above the surface of the water should MH's be placed? Is 6 to 8 inches far enough?

3. Is 4-1/2 watts per gallon enough for the average reef keepers needs? (some corals and maybe a clam)

Thanks for any ideas you have and any advice you can give.

[3_high_low]

my ideas:)

1) I would be happy with 20kk used with a HQI ballast. You might prefer something else. As far as what the creatures prefer, that's a major source of debate and you can find plenty of opinions if you do a search.

2) 6-8" sounds good as long as the bulbs won't be splashed or coated with salt creep.

3) Watts per gallon can be misleading. It depends more on the depth of the tank. A good reflector is important too.

[Tadashi]

If you have MH then VHOs are primarily for looks. I know people who like the look of 6500K and others that like the 20000K so it is up to you. I prefer the 12000K bulbs.

I have my bulbs about 6" up. My last setup was about 4" and I did not get any saltcreep. I also had my fans blowing across the water preventing the splash from reach the bulbs.

The strength of the bulb depends on your depth not the amount of water you have. You can have a 1000-gal tank that is only 6" tall and a 400-watt MH would be too much. I recommend anything above 24" you should have a 400-watt. At 17" of height you lose about 70% of your light (TRA Vol 1). I have a 30" tank and wish I had gotten a 400-watt MH.

[nanoguy]

I've seen the 20k bulbs on my friends tank (sps_guy) and I think it looks great. It has a nice blue tint to it and it really brings out the colors on the corals. The only downside that I've heard about the 20k's is that they don't last very long before the color starts to shift. Someone correct me if I'm wrong.