HQI fixture: How close to the water can I put it?

bureau13

New member
Well, I finally hung my Aqua Medic OceanLight (4x250W HQI + T5 supplemental). They suggest 6-12" over the water (my tank is acrylic for what its worth). The thing is, my tank is 36" deep, and I was borderline on whether I needed to go with 400W lamps. I ultimately decided on the 250W HQI but I want to maximize the light I do have, without causing problems.

Right now, I have them at about 11.5" over the water and on a reduced photo period so I don't shock the corals. I want to lower it though, both to get more light down to the lower regions of the tank, and because at that height its a bit too easy to see the lamps suspended above the tank....I'd prefer to NOT be able to have a direct line of sight from all over the room. I was thinking I would go down to the minimum recommended 6" but I thought I'd get feedback first...I don't want to melt my top center section, etc.

Thanks,
jds
 
You do have to be careful in regards to center braces and metal halides. I have had an AGA center brace break on me over time due to MH heat. If you center braces is pretty thick I wouldn't worry, but otherwise it's something to think about. I doubt a couple inches is going to make the difference on any potential problems. I have my lights at 8 inches and the problem. The biggest thing to worry about in regards to HQI and lowering it would be a splash on the UV glass. I've seen them shatter before because of a splash. Once this happens your corals are in serious trouble unless you catch it quick.
 
Actually its not really a brace on my tank...its more like the part of the top that's not cut out (there are two large openings in my tank, so I think of the center part which is not open as a "brace." In reality, its just part of the tank.

Good point about the splashing...I don't seem to be getting much, but I guess it would take one overly-exuberant fish and that would be it. I'll have to see what it looks like at 8" maybe that will be low enough.

jds
 
i have mine 6" off the water (2 250w hqi on a 75gal) and i dont get too much splashing and no broken glass. the same lights were on a buddy's 330gal acrilic tank and melted the top panel on the tank at the same height.
 
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