Metal Halide is a point light source, in that it distributes its light in a roughly 2'x2' area as opposed to a flourescent light that emits light from the whole length of the bulb (i.e. a 4' bulb will cover lighting over a 4' area).
If you put one MH
in the center over the brace, the brace will likely disrupt and/or block a fair amount of the useful light that is the brightest right under the bulb. Not to mention, it will also have the shadow that won't look so good as others have stated. The only way to have it really look good and be effective would be to have 2 MH
(1 centered between the left side and center brace, the other between the right side and the center brace). This will create the most useful light and keep shadowed areas to a minimum (good place for mushrooms, etc.).
Your stuck in a tough spot! If you add another PC
fixture to save money remember that is more electricity used probably than going MH
. Also included is multiple bulb replacements every 8-12 months (I have never made it even close to 12 months without a severe loss in intensity
). It becomes pretty much a choice of pay a lot at once, or a little over a long time. Your budget should dictate which is more reasonable when combined with what you want to keep.
Seeing that MH
is an expensive purchase for you(and for me....I still only have 1 instead of the 2 I need!), I doubt that you are going to be purchasing and keeping high light requiring SPS frags
and clams for $35-$85+ a pop so I would honestly go with 2x175w MH
or maybe 2x250w MH
to be able to keep a wide variety of corals. If you are "wood-workingly impaired" (a new word, don't check Webster's)....you could also consider the use of pendants that hang over your tank (but normally cost a bit more). Each 175w or 250w retro should cost around $190.00 (total for both assume $400) including everything you need to mount into the canopy. I would go with 14k bulbs and skip having to supplement with any kind of actinic for color (so maybe you could sell your existing PC
unit to offset the cost a bit?). I like and use Coralvue...have also heard good things about Hamilton but I have no direct experience. A fan may be necessary to get air moving through the canopy, but I'm sure a clip on variety could suffice or simply having the back out of the canopy and a few vent holes elsewhere. You have a lot of water volume to dissipate heat (ultimately will depend on the ambient temp of the room, etc.)
A lot to digest, but there are pros and cons to everything. Maybe this gives you more to chew on and decide which path is the best for you.