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#3
11/27/2007, 03:37 PM
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Re: WTB reflector
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-Kurt |
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#5
11/27/2007, 05:02 PM
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Rick |
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#6
11/27/2007, 05:05 PM
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Re: Re: WTB reflector
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Rick |
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#7
11/27/2007, 06:33 PM
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basically a hq is the inside of a halide- without the large glass envelope of a single end. The large envelope is what shields the uv- so the HQ blasts UV. Is this dangorous? well here is the lowdown as I see it-yeah for you if you look into an unshielded HQ it is not good for your eyes- I would make sure that there was no positon you would be in viewing or whatnot that would allow you to be in eye contact with the bulb. Livestock is where the fools start coming out of the wood work. Plain and simple water is a very effective filter of the dangerous UV rays- perhaps not as good as glass but close. Anything not at surface will not have issues. Most of the "science" you see on UV problems with animals are not done with any controls in place. Fact of the matter most I have seen have results that are not dissimilar from over illumination- which would make common sense in the fact that an unshielded bulb is going to put off a lot more light than one passing through, and being reflected by several thicknesses of glass.
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#8
11/27/2007, 06:57 PM
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I'm also curious as to which UV we are talking about UV-A, UV-B, or UV-C.
My understanding for the purpose of the glass was more to protect the bulb from water splashes and moisture as this would cause the bulb to rupture, thus the reason why you are instructed to use dry, clean cotton gloves when handling them; else the oils, even from a dry hand, would cause them to rupture when they got hot. With SE bulbs, they already have a glass outer cover as stated. It seems this UVR from HQI or SE isn't much different than what one gets from the sun or even arch welding, but as stated the SE bulbs have the outer glass already there, whereas the HQI bulbs do not. This isn't to say that a person could not put a glass panel below the bulb, which you would want to do anyway to keep it from exploding when errant water hits it. I was just reading an article where folks got "sunburns" sitting in a gymnasium for 3 hrs; come to find out a couple of the SE MH bulbs had their outer glass fractured and was allowing UVR to escape. So they got sunburns just like they had been sitting outside in the sun.
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Rick Last edited by medic29; 11/27/2007 at 07:11 PM. |
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#9
11/27/2007, 07:16 PM
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bpeugh,
More to the point in reference to your question; probably one of the most important, if not THE most important piece of equipment you will have for a reef tank is the reflector for your lighting. I will give you, the reflectors that are very good, also have high price tags for all they are, but they are good and you will see a huge difference in your reef tank. There are many of us who have had really basic reflectors of one sort of another, then eventually upgraded to one of the "better" reflectors and have personally experienced the difference. With that being said, you can still get okay results with the basic reflectors and unless you are striving for a tank with a lot of SPS the other reflectors will be okay. HTH
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Rick |
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#10
11/27/2007, 09:14 PM
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Basics about UV light
OK, so here's some basics about UV (ultraviolet) light.
First, we always hear UV A, B or C...what does that mean? It corresponds to the wavelength of the light UVA 400 nm - 320 nm -responsible for "aging" of skin UVB 320 nm - 290 nm -causes the sunburn UVC 290 nm - 100 nm - most dangerous- blocked by our atmosphere however produced by some lamps in high amounts Ok, so what bulbs emit UV light - essentially all bulbs do, even incandescent, what's important to consider is how much UV is emmitted and if it is shielded/absorbed. For example mercury arc lamps emit a lot of "UV C" light, however that light is converted by phosphor to visible light within the bulb. Incandescnet bulbs emit UV light and are not shielded, but the amount of UV light is minimal. With Metal Halide lamps there is usually a combo of argon, mercury and metals halides to create the color and intensity of light desired. These too require some sort of shielding to absorb the UV light emitted. This shielding can be a secondary "tube" around the light or the pane of glass that has a UV coating on it. Possible dangers of unshielded UV lights. To Humans- UV light can causes "sun burn" over short exposure and long term exposure can cause premature skin aging and cancer. The most likely target (and probably forst to be affected) are the eyes. Short-term exposure can cause a really really paniful condition in your eyes that feels like sandpaper on your eyes. This usually occur a few hours after exposure. Ask any welder about it...not pleasant. Long term exposure has been linked to cataract formation. For the marine aquaria- 25% UV light from the sun can pentrate 50 meters of clear tropical seawater. THe ocena looks blue because violet and UV light penetrate the deepest (Oceanus Magazine • Vol. 43, No.2 • 2004) So UV light can and will penetrate your tank ( syrinx - I thought it would be blocked too). The effect that that will have is questionable since tropical fish/inverts are exposed to significant UV light, especially species from the equatorial region, thusly many have no doubt adapted ways to protect themselves. Below is a chart of light penetration in water: Color Depth Red 5 m Orange 15m Yellow 30m Green 60m Blue 75m Indigo 85m Violet 100m Please note that this chart doesn't specify how they measured light penetration i.e. are these depths of complete absorbance? A few other comments about UV penetration: "For example, in the Atlantic Ocean, Z10% 305 nm, Z10% 340 nm and Z10% DNA can reach 17, 38 and 12 m, respectively." Penetration of Ultraviolet Radiation in the Marine Environment. A Review Photochemistry and Photobiology, Mar/Apr 2006 So the bottom line is that running an unshielded bulb is very risky, especially to people viewing the tank. Last edited by webbstock; 11/27/2007 at 09:32 PM. |
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#11
11/27/2007, 10:07 PM
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I will also add that many have reported corals getting burned when thier SE bulbs have a crack in them. Its not uncommon.
Either way, I think you would be foolish to run the bulb w/out the glass. Now if you want, your more than welcome to go get an elcheapo light fixture from Walmart, but dont expect it to perform all that well. But based on your needs, perhaps you dont care anyway....but for those who do..............
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#14
11/27/2007, 11:20 PM
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I probably should go to an enclosed glass structure though. I will go over to Springfield Electric tomorrow to see what they have. I guess the optimum thing would be to find a glass bottomed metal box 18"x6" that has slanted sides to put the reflective material on. Didn't mean to be so jerky about it but I have no real desire to grow large amounts of SPS. Thanks.
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#15
11/27/2007, 11:24 PM
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Obviously i will defer to webstocks findings- although i still question the penatration of uv in damaging amounts. I will digress into history a bit here though- I was the first downstate illinois dealer for hydrofarms and several other halide manufactures. Back then only the top sps people had any intrest, because all the experts said the UV output would kill corals. Other facts- you can get a sunburn from a single ended halide- usually you have to have 1000 watts- but some of my overdriven 400s(430s) will cause pain. I have had people get physically ill from being around high powered systems also. The whole wearing gloves in bulb replacment is something that is much more recent than halides- it was first really instituted for halogen bulbs, and HQ halides. I have changed more SE bulbs without gloves than some of you have had hot meals and there is never been a problem- nor have I ever seen one first hand in 10 years of sales. The key thing to remember is- these things are not toys- protect your health, and keep an eye on your animals. If they are in good health, then no matter what anyone says- they are in good health.
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#17
11/28/2007, 08:55 AM
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Quote:
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-Kurt |
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#20
12/02/2007, 04:37 PM
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Re: reflector
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http://www.hellolights.com/index.asp...OD&ProdID=1439 From that link: "* Do not mount "double ended" HQI type bulbs without a UV filtering glass shield!! This bulb will put out UV radiation which can damage your eyes and skin, as well as your animals in the tank. The bulb MUST BE burned behind a protective glass sheet." Another similar note from Premium Aquatics about thier DE bulbs: UV NOTE: Double ended bulbs do not have the enclosed glass like the Mogul screw in type lamps. This means they have no UV shield. You should never run a double ended bulb with out the glass shield. UV damaged can result in your corals, especially gorgonians.
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-Kurt |
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