halide question
 

since i started I've been using a 3mm sheet of glass to block out the excess UV from my two hqi's, but now with a 1x400 mogul, I don't really need a sheet of glass any more do I? I've never had heat problems with a sheet of glass, but with a 400 watt would it cause the temperature to skyrocket?

A misconception with 400w is you can have them higher up with more air movement.If you have the space that is

i have lots of space, the whole aluminum housing will be hung from the ceiling so I'll be able to adjust it heightwise, so no glass?

Only HQI bulbs need a piece of glass because they produce UV rays. A mogul based bulb does not produce any UV rays so it does not need any glass. Hope this helps.

Glass over the tank will actually cause greater heat build up. Plus it will stop needed gas exchange. I would never recommed glass over the tank. With HQI It is best to have a glass cover on the light fixture

J

Not so sure about this statement:
" A mogul based bulb does not produce any UV rays so it does not need any glass."
I agree with Jason having tempered glass covering the light is better. Any salt spray is going to accumulate on hot surfaces faster. If you get some on the bulb it may cause some hot spots on the surface of the bulb and burn it out.

ya i'm with you on that one, i'm pretty sure moguls produce the same type and amount of short wave uv radiation, but moguls have an out envelope, to retain the harmful type of uv exposure, correct me if i'm wrong :smile:

ya i'm definitely ditching the glass jason, wouldn't trust it with a 400 watt, however i'm definitely not a fan of the ''non-covered tank'' especially with such aggressive eaters, and my fairy wrasse, whose always so hyper and an active jumper, so what could i use for a cover, eggcrate, too hot for eggcrate maybe? the bulb will be no closer than 10'' from the surface

Mogul base bulbs do produce UV but the glass envelope of the bulb is the shield. A mogul bulb is nothing but a HQI bulb with a built on UV shield.
ALL HQI bulbs MUST use a separate UV shield.

what problems does the UV cause,I know the sun produces UV and I dont hear the ocean complaining

Aside from burning your retinas out. Can trigger all sorts of nasty skin problems...the C word comes to mind.

Exactly

J

http://www.masla.com/reef/uvlighting.html

Perhaps read this article. SE bulbs still produce a lot of UV light.

good thread just finished it, darn they didn't have the xm's just coralifes they used for the experiments.

so what should use to cover the top of my tank then? eggcrate?

Interesting artical Doug. Odd that more action is not taken to combate SE UV.

J

And yet I was reading an article in a magazine several months ago that using UV emiting bulbs may be the next frontier of reef keeping . I.E. the acros that are near the waters surface or even exposed during low tide and the relationship of the sun's effects.

we should just move our tanks outside.Its the natural thing to do

Yes, I always thought it was. It came to mind when I seen you guys discussing uv, so had to go find it again. I have ran both ways. Like most, with no glass, using SE bulbs but I also ran my PFO pendants with the uv glass in and liked them that way also. I dont know what was loss in output, as I never measured.

The UV will kill anything that is under the light. Fish will eventually be blinded not to mention the harm to you. Think about it...you can sterilize tank water with a 9W UV sterilizer, think what a 400W bulb will do to a tank. Also, just some regular old piece of glass wont do.

Are you refering to DE bulbs or blocking UV from SE bulbs, as Dana talked about?

No actually just the unshielded DE bulbs. I forgot to put the quote in my post. Fixed now.
Actually its not a bad idea to have splash guards on SE bulbs too. They run very hot and a splash could cause the outer envelope to crack or break.
There was a post awhile back from a guy who had that happen and he didnt notice it. First his anemone relocated to the opposite end of the tank and then over the next 2 weeks every coral in the 1 half of the tank died. Unfortunately he discovered the bulb too late when he removed the canopy to clean up the mess.