Help with MH

[RadioPlay]

Hey guys, say I currently have a 4xPC hood which recently has had some issues. The cooling fan went bad and one of the PC ballast over heated and burnt out. So I was curious if it woul be possible to rearrange sockets in the hood and add a 175W MH?

My plan would be to remove two of the four 65W PC sockets that were attached to the burntout ballast and center a MH mogel socket in the hood. My concern would be if the hood would overheat with a MH lamp. Also the hood has a plastic protective splash gaurd that seals the bottom of the hood. Would the MH be too hot for the splash gaurd?

Any help would be greatly appreciated, thanks!

Radio

[charlie]

I am thinking that the splash guard is plastic? If so, I don't really think you want to put a MH in there. That and the fact that the fan is DOA, makes for not a good situation. JMHO

[RadioPlay]

Thanks for your reply. The fan wasn't DOA, I've had my reef up for 3-4yrs. The fan recently went out.

Also I'm sure the reason the splash gaurd is plastic is due to the low level of heat with PCs. The refletor is nice, the hood itself is a solid hood. I just don't want to buy a whole new hood when I plan on upgrading my tank in the future.

[dougc]

I wouldn't put an MH bulb into an enclosed fixture that wasn't designed for it. The bulbs generate a tremendous amount of heat. You would really need to add a proper reflector, too, and there probably wouldn't be room for that. Lots of people use "retrofit" kits for metal halide lighting, but they are usually not completely enclosed in a fixture.

[RadioPlay]

Thanks for your feedback! I guess I'm not seeing the difference between the setup I'm talking about and a retrofit kit like the one I have attached, except obviously I'm using CF vs. VHO. Reflector looks the same and I'm kind of lost on what you mean fully enclosed, don't all MH hoods have a sheild to protect from bursting bulbs? I know I'm showing my ignorance of lighting but that's what forums are all about!


Radio

[Reefland]

RadioPlay,

If you could get a setup like that in your hood you should be fine. However as mentioned, the plastic splash guard should be cut out and the hood would need to be positioned so the bulbs were at least 5" from the surface, higher if possible.

The reflector pictured does help reflect light into the tank, but not as well as a proper reflector as Doug mentioned. Something like a Spider Reflector would be much more effective.

[RadioPlay]

Thanks Scott! The splash gaurd can be removed. I'll take a picture of it tonight and hopefully you guys can tell me if I'm crazy.

Radio

[Reefland]

Is the hood itself made of ABS plastic?

[dougc]

The retrofit kit in the picture uses single-ended metal halide bulbs. Typically, a glass shield is not needed because the bulb itself has a glass envelope that blocks ultraviolet light emitted by the bulb. Double-ended bulbs must be shielded because they lack that glass envelope.

Retrofits are usually mounted inside a canopy, which I would not classify as a "hood". A canopy usually has much more space for heat dissipation and, if fully enclosed, will have large fans to vent better. My canopy, for example, is completely open on the top, covered only by eggcrate lighting grids (to prevent jumping fish from escaping).

A hood usually has enough room for bulbs, fans, and not much more. In commercial fixtures that combine metal halide bulbs and power compacts or VHOs, the hood is either oversized or the metal halide bulb is physically separated from the flourescent bulbs. It will also be constructed with materials (wiring, endcaps) that can endure high heat. Many plastics will quickly degrade when exposed to the heat generated by the MH bulbs. Even in purpose-built fixtures, there have been problems with heat buildup causing premature failure of components, especially in those that have the ballasts built into the fixture.

I guess we will have to await pictures of the fixture to comment further.