# Can a metal halide bulb touch the protective glass?



## Opiesilver (Nov 3, 2003)

Yes, it's going to be a problem for you. When the bulb is in contact with something that point on the bulb becomes a heat sink and the glass temperature on that point of the bulb will become unstable and may cause the bulb to burst. It's the same reason that you don't want water to ever touch a MH in operation.


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## audiotaylor (Apr 2, 2004)

What if I had it just very close to the glass but not touching? Is there like a minimum distance there needs to be between the two?


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## Opiesilver (Nov 3, 2003)

Should be ok if it's not actually touching.


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## audiotaylor (Apr 2, 2004)

Thanks!
-David


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## eums (Sep 16, 2004)

you do need that glass and if its too close it will crack. ( i have seen it happen when some one made a retro fixture for a de bulb. 

do not run the fixture if the glass cracks or is not in. the UV from the bulb will kill the fish and plants in a day. 

besf of luck with it. you may want to post what kind of bulb holder you need. i know of some that are low. what one of the pictured ones do you have ? the first one pictured is the smallest they make.

something like this is what you need i think ( the ones pictured are for 150W DE halides. ) there about $19
you can take out the metal bracket and mount the holder with out it and gain about .2"









The other type is this one .... i think the first one is much better quality and worth the $5 extra .


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## audiotaylor (Apr 2, 2004)

Of course I will be using the glass. I really dont see it cracking as long as I dont have the bulb touching it. It was, after all, designed to take the extreme heat that a metal halide bulb creates. I used the sockets in your second pic (







) 

This is the original socket my fixture came with-










and this is how I installed the new sockets-



















In retrospect, the model shown in your first pic might have been a better choice as it would have kept the bulb about the same height as the original sockets did. But as long as how I did it works, Ill be happy. Thanks for your input.


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## rkundla (Mar 25, 2004)

It is amazing how much heat a metal halide bulb puts out. I had a 175W SE bulb six inches from a glass top on my 75gal and when a fish splashed water on the glass top, it cracked. :icon_frow 

Switched to 150W DE and egg crate. Works much better now.

With the bulb so close to the UV glass, it might weaken it if it ever gets wet. I think my AquaMedic light has an inch of clearance from the edge of the bulb to the UV glass and it gets pretty damn hot.

The only other problem is that your bulb will be outside the sweet spot of that reflector, so you might get some wierd light pattern issues or excessive reflections into the bulb.

Ron


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## eums (Sep 16, 2004)

i would still recomend you buy the lower holder. and make some kind of braket to put it at the correct hight. or if you wanna spend about $200 get some new pendants (2). i would recomend the 150W reef optic III's and just wire your ballasts to them. 

that would yeild more light into the tank and be a better enclosure for the bulbs. but that would be if money just grew on tree's ...


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## audiotaylor (Apr 2, 2004)

I just wanted to let you all know that I did end up buying the better socket model from emus' post ( http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=4309967063&ssPageName=STRK:MEWN:IT ) and retro-fitted it into my fixture. Heres a couple pics of the finished install, thanks again to all who helped. Take care.
-David


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## Opiesilver (Nov 3, 2003)

Very nice job.


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