What lighting do I need

[Thunderkat]

Metal halides are terrible, just upgraded to some on my 75 and they are not that good. I have two really bright spots in the middle of my tank and the edges of the tank are actually kind of dark. There is also a shimmer effect on the edges that I do not like. When I get to my next duty station I think I am just going to load up the tank with tons of sand to make the tank more shallow and use the flouresent bulbs.

[GaryP]

That's probably not because of the MH, but rather the reflectors that you are using. Some are better then others at spreading the light.

[alton]

I just gutted a 4' Orbit and used the same reflector that was in it. And my tank looks fairly even. Thunderkat what kind of fixture are you using?

[matt]

2 250W double ended mini pendents would be ideal for a 75 gallon tank IMO. Since you have an open top tank this is the easiest solution; jjust hang them from the ceiling and plug 'em in. They're pretty focused so you won't have light blasting all over the room, and the light quality is terrific. If you want to build a canopy, you can do the retro fit as suggested, but make sure you get quality reflectors, and it does have the advantage of being able to use VHO actinics to improve the color. But, there's a good heat advantage to an open top tank in this climate, and there are many excellent bulbs to choose from so the actinic support is not as important as it used to be.

Most people would disagree with thunderkat on this issue; for a reef tank, especially clams, MH lighting is the preferred choice. The shimmer lines come from the light being a point source, and are considered very natural and desirable; like sunlight making patterns on the ocean with the waves.

[Ross]

Agreed with matt, go with metal halide. I have seen tons of tanks which i have based my opinion on, metal halide is the only way to go. If you go with PC's you will be wasting your money and time. They dont have near the intensity of a mh.