Metal Halide w/ glass cover?

[jjwill_sdsu]

So this may sound like a silly question, but I have just not seen it mentioned in any of the posts I've been browsing. I was considering getting a MH fixture to stand (not hang over) on my 72 gallon bowfront. In the past, I have kept the standard glass covers on the tank with my PC lighting. It recently dawned on me that I don't recall seeing any setups with a "closed" tank surface (i.e. the tank surface is open with a glass enclosure only surrounding the MH bulbs themselves to prevent any water damage). I was planning on leaving the covers on to reduce evaporation, noise, jumping possibilities, etc., but is that a bad idea with MH fixtures? Are there concerns for the MH overheating the water (even more than normal for MH) or the glass significantly reducing lighting quality? Just wondering if anyone knows of any problems with that approach or if I should be looking into other lighting alternatives. Thanks.

 

[wangotango]

Welcome to the boards

Personally I'd take the covers off. Leaving them on will inhibit gas exchange, cause temperature problems, and will get covered in salt blocking the light. If you've got fish that are known to jump you can cover the top in a sheet of eggcrate.
Most MH fixtures have a glass or plexiglass cover to protect the bulb from splash, if not just make sure its at least 4" or so above the water surface.
-Justin

 

[acrylic51]

Is the MH SE or DE bulb? If it's SE (single end) bulb I'd remove the cover, but if it's DE (double end) the covers are there for a reason for UV shielding and need to stay....HTH

 

[aquaguy24]

eggcrates will work but it will still defuse some of the light and reflect some light into the room also..