[scubadude]

My question is directly related to the 250watt HQI bulbs, Im in the process of building my 220gal Reef tank (72"x24"x30") which will be mostly SPS, and some softies, and LPS in there too. I am gonna build my own lighting system which will house 3 maybe 4 of the 250 HQI bulbs, as I have read Sanjay Joshi's report and love the par and spectrum that they emit, However what concerns me is the UV rays that these lights emit. My tank will be in my Office about 2' away from where I sit for 10hrs a day 6 days a week, and I dont want to have Skin Cancer after 6 mos I have talked with numerous glass shops and have read an indepth thread at ReefCentral about these DIY HQI lamps, As the glass shielding is what it all boils down to....What type of glass, and how thick should it be. There are a few things relative here from what I see....Heat, UV rays good to corals (SPS), UV rays bad to corals, and color spectrum. Most of the guys that have replied to this thread on ReefCentral seem to think that 1/4 tempered glass should be fine for shielding the UV rays enough to not cause damage, however talking to many glass experts in the past few days they have told me that regular 1/4" tempered glass does NOT shield that much of the U/V rays. I want the best of both worlds. I want to give my corals all that they need/want from these lights, and at the same time block out what can damage the corals and/or me. I have been told that their is 3 different types of UV A, B, and C. Which ones are good and which are bad? Or have I been misled? As far as glass goes its Measured In SHGC (Solar Heat Gain Coefficient) The higher the SHGC the more U/V will pass through it. There is also VT (Visual Transmittance) Which from the way the Glass experts explained it to me that the Higher the VT the Less par goes through the glass. This is all speculation on my behalf, I am by NO means a glass or light physics expert. My Glass man has told me that if I can tell him exactly which UV's I want to block and Which I dont want to block then he can probably supply the correct glass, now the other thing that he has told me is opaque tinting or filming layers in certain types of glass will block UV rays I.E.: a clear piece doesnt block much UV's, a slight opaque blue will block some UVs, and a slight blue green will block even more, and a green will block even more than the blue green etc etc. This particular glass he was discussing is called Low E glass and is made with a Pyrolitic coat as well as a Monolithic coat. My thoughts where that a shade of blue or even blue green may accomplish that "Perfect Coloring" effect and at the same time elliminating our harmful UV's ? here again this is all speculation....tell me what you think.

Here is the thread that most of this evolved around

http://www.reefcentral.com/vbulletin...threadid=32376

Warning: The thread is about 8 pages long

Any input you can give me would be greatly appreciated! If you feel up to it then you can just email me or just post your response right onto the thread.

[organicreefer]

hey scuba, are they pendants ?if you have a canopy the light will have to pass through the 1/4 plate glass suggested,the water and then the tank glass,uv shouldnt be an issue in that case

[scubadude]

Originally posted by organicreefer
hey scuba, are they pendants ?if you have a canopy the light will have to pass through the 1/4 plate glass suggested,the water and then the tank glass,uv shouldnt be an issue in that case

No this is a DIY large canopy ( 6' long ) with DIY ballast, bulb, socket, reflector....whole nine yards....HQI puts out almost twice as much U/V as any other MH bulbs....so I dont think its as simple as installing a 1/4" piece of plate glass....I dont think neway.

[Ninong]

Scubadude,

I believe this article will answer all of your questions concerning exactly what UV is and what it does, as well as giving you information on the transmission properties of various shielding materials: http://www.aquarium-design.com/reef/uvlighting.html

Remember that the double-ended style HQI lamps do not have a protective borosilicate glass envelope around them like mogul based metal halide lamps and that is why they emit more UV when measured without a shield in place. This unshielded radiation would be harmful to the animals in your tank as well as the animals outside your tank. As a matter of fact, I have found that virtually all of the popular hobby authors now recommend shielding even for mogul based metal halide lamps since they are of the opinion that the glass envelopes are not really adequate.

You might consider contacting one of the fixture manufactures, such as www.hamiltontechnology.com , to see if they would sell you a piece of shielding material (glass or whatever) cut to size. I don't know if they will or not, but at least they should have a better handle on exactly what is required than the local glass shop.

Regards,

Ninong

[scubadude]

Originally posted by Ninong
Scubadude,

I believe this article will answer .........

Ninong

YES!!! Thats exactly the kind of info I needed!

Thanx Ninong!....and welcome back....glad to see you made it back in one piece....heard about your delay in CA

[organicreefer]

man ninong good to have you back,and right back in top form .i skimmed the article and i guess i will read it when i have time but it says i should be using a sheild of some kind with my regular halides my 400 watt iwasaki will be in the middle right above my center brace so does that count as "sheilding?it will only help a little i guess huh?i also will have a 175 on either side.glass top on my tank?unheard of!but..........i guess the sump is where i put my fan anyway...

[Ltspd]

Had a long conversation with the product manager for the aquarium bulbs for USHIO today. Nice guy, very helpful. He basically said the same thing as Ninong, that even the mogual base bulbs do not as a general rule have any UV special coating. Some do, but he didnt know of a aquarium related bulb that did, at least by Ushio. He sent me a link for some "other" sources that might have some UV glass or special coating. Since he/Ushio doesnt deal with the pendants themselves, only the bulbs, the UV protection end is left up to the next in line. He said that most applications of MH bulbs the UV isnt a real problem becasue of the cover of the fixture and the distance away from us animals. Since we are much closer, along with our livestock this changes that mindset. He said that there is a lack of good scientific study in relation to aquarium bulbs and UV.

Ninong, thanks for the link. From the brief scan of it, it looks as if lexan is the best bet overall. Least amount of loss and most amount of UV protection. I am assuming the solar lexan is also what i found called lexan 10. The one concern is that the minimual thickness and the heat issue of the lamps themselves may be of conflict.


Link from Ushio

http://www.lightsearch.com/search/co...urelenses.html

Product managers name is "Asato, Craig casato@ushio.com

[Ltspd]

Lexan 10 or solar lexan

http://www.polymerplastics.com/transparents_lexan.shtml


If .125 will transmitt 86% what will thiner sheets do? 3/32 is .09375 and this is the number used in the article

[scubadude]

UV-A
UV-B
UV-C

I had a chance to talk to Sanjay Joshi on the phone yesterday and he explained what he could to me about the U/V spectrum and that UV-A does not show up that much in the aquarium bulbs (MH and HQI) at least not enough for us to worry about shielding it. However UV-B and UV-C can pose a threat. However he told me to do the same thing that Ninong suggested! Call PFO, or Hamilton....Which I did, I called Hamilton they actually sell U/V protective shields and recommended to me 1/4" Tempered glass Well after further conversation w/this guy he tells me hes not for sure that its just plain glass that I would have to talk to his boss...So guess it will be monday! Yes Paul Lexan is definately a good shielding property but it would cost me almost $150 for the size I need! I will go that route if need be....but I was hoping for a more effecient source....Guess I cant have my cake and eat it too...huh.

[Ltspd]

Like the guy from Ushio said, if you were directly under it 8hrs a day youd get a suntan. The corals and fish have means to prevent tanning, or atleast tan lines

Still makes me wonder if glass isnt the best....

[scubadude]

What about this AtoHaus UF-3** in the link Ninong provided us? That has much better par transmission and still has a very low UV transmission! Well I Might be able to talk to my glass man today....Im gonna get prices on a few different pieces and also ask him about strengths, tempering, etc. etc....I will let you know the outcome...Thanx Paul!

[Ltspd]

Just got off the phone with a friend, a local reefer with a large tank, and years more experience than I. He questioned the fact of do we need to be really this concerend with the UV issue? The corals can and deal with it in the wild. The bulbs put out similar UV properties to the real thing, the sun. So do we need to worry about it? Like the Ushio guy said IF we were in direct contact with it for 8hrs or what ever then it may be a problem, but since we are looking at the light basically filtered thru the water does it still pose a problem? I have my hands and arms in the tank all the time, with the Iwasaki's burning. Cant say I have noticed one arm tanner than the other Scuba, you are worried about it being in your office while you are there all day, but whats the diffrence their from your/others house?

I dont know, feel like I am chasing my tail Just cant seem to find the end or atleast the right end.

Will good old glass work? Do we need to concern ourselves with the whole UV thing? The standard MH bulbs we use put out UV, why should the HQI's covered by glass in our DIY hood be any diffrent?

[Ninong]

Ltspd,

Uh oh, you're missing a lot here.

There is no comparison between the UV levels transmitted by double-ended HQI lamps that have no outer glass envelope around the central bulb and other metal halide lamps that do have a somewhat effective protective outer glass envelope. Just check out the figures from Sanjay's tests.

All UV-C is deadly; however, UV-C from the sun is absorbed by the earth's atmosphere (unless you're in Tierra del Fuego when the hole in the ozone layer is directly overhead--j/k).

UV-B is biologically destructive to all animal life but not necessarily deadly. Prolonged exposure can result in harm.

UV-A is not nearly as much of a problem and a certain amount of UV-A is beneficial.

It is quite possible that metal halide lamps that have a protective outer glass envelope are reasonably safe if positioned the proper distance above the water. However, people who have studied this question and measured these emmissions recommend otherwise... possibly in an excess of caution more out of concern for the animals outside the tank.

It is NEVER safe to operate standard double-ended HQI lamps without proper shielding in place. Never.

Regards,

Ninong

[Ltspd]

Ok, Ninong help me out.

Originally posted by http://www.aquarium-design.com/reef/uvlighting.html
For comparisons, this instrument reports maximum temperate latitude UV-A as about 2000-2,100 µW; UV-B is about 1,000 µW. Measurements taken in Hawai’i (Makena Landing, Maui) at noon on a sunny November day showed UV-A as 1,260 µW and UV-B as 960 µW.

Now as told by the Ushio Product manager for aquarium bulbs, Maybe we know somthing he doesnt.

Originally posted by Ltspd

even the mogual base bulbs do not as a general rule have any UV special coating. Some do, but he didnt know of a aquarium related bulb that did, at least by Ushio.

Now according to Figure 4, of http://www.aquarium-design.com/reef/uvlighting.html
The AB 175w 10kk mogual bulb produces UV-A well below the natural sunlight. Or atleast this is how I read it.
Table 2 basically agrees with this, putting the 3 bulbs tested close to the natural sunlight.

Table 4 points out that if we set our bulbs at what most people set theirs above the water then we are "in range" with natural sunlight. Approx 400-800 micro E's

Now Ninong, I am not disagreing with you on the point of Double ended HQI bulbs needing further protection, but I have 2 questions.

1) You have a HQI fixture, If I remeber correctly not a pendant. Do you have special glass? How do you know?

2) If what the Ushio Product Manager told me is true then why do we need further protection other than glass? The corals are getting the same stuff in the wild as we are dishing out in the tank, correct?

The article goes on to say that reducing/Eliminating UV shows good coral health and coloration, so I buy that aspect, but arent we trying to duplicate the wild? Arent we getting MOST of our corals from the wild, atleast 1st generation.

Now I agree, myself and others need to reduce/eliminate UV-a and UV-B. If I didnt I wouldnt be pursuing this end of the diy.

Whats confusing me is whats diffrent from the wild? Our protection?

I will be using lexan XL (3/32 or .09375) more than likely. It has the most UV protection and fair pass through, 1% diffrence over AtoHaus UF-3. Of corse this is based cost, if the UF-3 is cheaper and easy to come by I will go that route

[Ltspd]

http://www.reefcentral.com/vbulletin...threadid=37990


Or the thread response posoted here thru the miricle of moder computing.

posted by Eric Borneman

My feeling is that there is no way that UV from those lamps will cause any problems at all provided you allow your corals to photacclimate slowly. They are more than capable of tolerating UV at that level. Corals produce highly efficient UV sunscreen compounds.

[Ninong]

Originally posted by Ltspd:
Now as told by the Ushio Product manager for aquarium bulbs, Maybe we know somthing he doesnt.

even the mogual base bulbs do not as a general rule have any UV special coating. Some do, but he didnt know of a aquarium related bulb that did, at least by Ushio.

The Ushio Product Manager is obviously confused about his own products. Refer him to his corporate website to refresh his product information.

Ushio does not use any sort of UV-absorbing protective coatings on any of their lamps. In fact, I don't know of any manufacturers that do. Ushio does offer, on some lamps, optional UV-absorbing quartz glass (what I refer to as borosilicate glass).

>1) You have a HQI fixture, If I remeber correctly not a pendant. Do you have special glass? How do you know?

I have an AB-Aqualine Aquastarlight Future fixture. Yes, I have special glass. How do I know? Because I research everything to death before I buy it. According to the AB-Aqualine catalogue: "The housing is made of powder coated corrosion resistant aluminum, with special reflectors and safety glass." I just inspected my fixture and the safety glass is stamped "SCHOTT, DURAX."

>2) If what the Ushio Product Manager told me is true then why do we need further protection other than glass? The corals are getting the same stuff in the wild as we are dishing out in the tank, correct?

OK, forget about the Ushio Product Manager, because he obviously is not well informed if he is talking about special coatings. Since I believe you already recognize the need for protective shielding when using standard double-ended HQI lamps, I will assume that you are talking about regular metal halide lamps that come with UV-absorbing quartz glass envelopes. Is further protection required. I don't know. But Dana Riddle and Robert Fenner both say it is. If you want to talk about what UV radiation levels are in the wild as compared to UV radiation that is emitted from metal halide lamps, you should refer to all of the articles online by Sanjay Joshi and Dana Riddle, et al, that cover this topic in detail. In the case of unshielded double-ended metal halide lamps, these lamps emit a certain amount of UV in a range that is not present at the earth's surface. In the case of regular metal halide lamps with quartz glass UV-absorbing envelopes, some hobby authors recommend additional protection. Take your pick, and take your chances.

I wouldn't worry too much about totally eliminating UV-A... not necessary. I would worry about UV-B. And UV-C is also known as a UV sterilizer, quite good at killing things at proper flow rates and dosages.

I'm afraid I can't help you on the selection of a good UV-absorbing shield material. I took the easy way out and purchased a ready-made fixture that had all that good stuff to begin with.

Later,

Ninong

P.S. - I just reread one of my previous responses in this thread and I'm not sure if you caught this, but this is what I posted:

"It is quite possible that metal halide lamps that have a protective outer glass envelope are reasonably safe if positioned the proper distance above the water. However, people who have studied this question and measured these emissions recommend otherwise... possibly in an excess of caution more out of concern for the animals outside the tank."

[Ltspd]

I wonder why Eric Borneman states diffrent?

I guess I am dazed and confused about the whole issue

Ok, whats SCHOTT, DURAX? Sorry the only German I know is bratwerst

I have the AB Aqualine 10000 bulbs, which is what I got from http://www.customaquatic.com/customaquatic/index.asp

I wonder if they have a better glass sheild?

Ninong I know you have their site.

[Ninong]

Originally posted by Ltspd
I wonder why Eric Borneman states diffrent?

Good question.

I just asked him that same question in that thread:

"Eric,

I'm not sure that you realize that the lamps in question here are standard Ushio 10,000K 250w HQI double-ended lamps that Scubadude intends to build into a DIY setup. Everything that I have read about double-ended HQI lamps states that for the health of the animals inside the tank, as well as the animals outside the tank, a protective glass or plastic shield must always be used. These lamps are usually marketed in a ready-made fixture that incorporates protective shielding. We are not talking about regular mogul based lamps that come with UV-absorbing quartz glass outer envelopes.

To quote Sanjay Joshi: "The UV output of the various lamps is shown in Figure 5. Comparing the UV output in this chart is somewhat misleading. The double-ended lamp has much higher output than the others, but remember this lamp requires a UV filter, which would bring this number down."

Please clarify your response.

Thanks,

Ninong"


>Ok, whats SCHOTT, DURAX? Sorry the only German I know is bratwerst

I assume that SCHOTT is the name of the manufacturer and DURAX is the product brand name.

>I have the AB Aqualine 10000 bulbs, which is what I got from http://www.customaquatic.com/customaquatic/index.asp

I wonder if they have a better glass sheild?

All double-ended HQI lamps must be used with a protective shield. I have never, ever read anything contrary to that until I read Eric's post. I believe Eric may have misread the question. He may think that Scubadude is asking about mogul based metal halide lamps.

>Ninong I know you have their site.

I have everybody's site: www.ab-aqualine.de

Ninong

[Ltspd]

I will be curious of his response also.

[Ninong]

Ltspd,

Regarding whether or not HQI double-ended lamps require protective UV-absorbing shielding, I would like to quote from Dr. Sanjay Joshi's site:

"The double-ended HQI lamp is very different from the other lamps tested. It is double ended, while all the others have a single screw-type base. It lacks the outer ultraviolet (UV) filtering glass bulb of the other lamps. This lamp must be used in an enclosed fixture with an UV protective shield. It does have a very nice color and has the best spectral curve of any of the higher CCT lamps tested."

Also: "The UV output of the various lamps is shown in Figure 5. Comparing the UV output in this chart is somewhat misleading. The double-ended lamp has much higher output than the others, but remember this lamp requires a UV filter, which would bring this number down."

We have discussed this issue on Reef Central and Reefs.org in the past and a few members have posted of killing many of their corals by using HQI double-ended without any protective shielding. I may be able to find the exact threads for you if I feel up to it.

One thing that you may not be aware of is the fact that an unshielded HQI double-ended lamp produces UV light in a range that does not even register on the equipment that Sanjay used in his testing. Just take a look at his charts.

I am not sure what Eric means when he says, "and I don't feel that UV in these amounts is something to be feared for coral health unless it is in combination with other stressors such as temperature and light shock and salinity."

What amounts? Did someone post quantitative values for an unshielded 250w double-ended HQI lamp?

In any case, Eric says that he believes that double-ended HQI lamps should be shielded for safety reasons but not for reasons of causing damage to the corals if unshielded. All I can say is that that is the first time I have come across that opinion.

Ninong

P.S. - Don't forget that you cannot blow air directly across an exposed double-ended HQI lamp because these lamps must burn at a certain high temperature, otherwise it will effect their color and their lifespan.

Additional information and informative threads on this subject:

"Do not run HQI bulbs without a shield in place! Not only will you get UV damage to your eyes and marine life, the HQI envelope gets to about 3000 degrees and will send red hot quartz fragments everywhere if it gets splashed."
Matt Marulla
Inland Reef Aquaria
Nashua, NH
http://www.reefs.org/cgi-bin/ultimat...c&f=1&t=025624

http://www.reefs.org/cgi-bin/ultimat...c&f=1&t=025947

http://www.reefs.org/cgi-bin/ultimat...c&f=1&t=026581

"You really do need UV absorbing glass for a filter. I have tried acrylic and it did not do much to reduce the UV, even though the specs would indicate otherwise. Tap Plastics does have a UV coated OP-3 version that might work, but you would need to keep it a fair distance away from the light. In my case I tried using 1/4" acrylic with a 70W HQI at a distance of about 7" (with air flow) and there was no problem with the heat. In the case of the 575W HQI, I actually used an inverse acrylic fresnel lens to spread the light out, but that was after filtering excess UV/IR out with filters.

My installs were DIY's, but I have access to special UV filters through my work. I have heard people mention that some of the picture framing glass which have UV coatings to protect the pictures might be a good option to try for a DIY setup as well. Best bet is to buy the premade setups, but the housings do restrict the light spread some.

--- Ken"

http://www.reefs.org/cgi-bin/ultimat...c&f=1&t=028873

OK, I'm now searching the Reef Central site but it's going to take awhile... there are 586 threads on HQI.

http://www.reefcentral.com/vbulletin...&highlight=HQI

http://www.reefcentral.com/vbulletin...&highlight=HQI

http://www.reefcentral.com/vbulletin...&highlight=HQI

http://www.reefcentral.com/vbulletin...&highlight=HQI

http://www.reefcentral.com/vbulletin...&highlight=HQI

http://www.reefcentral.com/vbulletin...&highlight=HQI


What I am really looking for is the complete spectral emission range of an unshielded Ushio 10,000K 250w HQI double-ended lamp. I suspect that there is a certain amount of UV-C from these lamps. It may be a very small amount, but if there is any at all then all the MAAs in the world wouldn't help you because they protect against UV-A and UV-B only because no UV-C from the sun reaches the ocean's surface--it is all absorbed by the earth's atmosphere. Mycosporines show an absorption maxima around 320-335 nm which is well into UV-A range (UV-A = 320-400 nm, UV-B = 280-320 nm, and UV-C is below 280 nm). Most shallow water corals have developed MAAs to protect them against UV-A and UV-B because the earth's ozone layer near the equator is very thin and tropical ocean waters are very transparent to UV radiation. I doubt that deeper water corals would have the same level of protection and these corals might be kept in your reef tank. In any event, this adaptaton is not instantaneous... it take some time. Kinda like you going out on the beach for the first time.

There is no question that UV radiation does have certain harmful effects on corals and it is true that corals have developed MAAs to protect them against these harmful effects, to a certain extent. The reason corals spawn at night is because their gametes would be damaged by UV radiation. Porites have been shown to exhibit reduced growth and possible photoinhibition when exposed to UV in a range of 310-350 nm. So my question is why would you want to subject your corals to additional stress unnecessarily?

In any case, if I can find anything that shows significant UV emissions from these double-ended HQI lamps below 300 nm I will post it here. This might be an interesting question to pose to Sanjay Joshi... not from the standpoint of coral adaptation but from the standpoint of UV irradiance of these lamps.

OK, I found the information I was looking for on Sanjay's site. As you can see from this chart, the Ushio 10,000K 250w HQI double-ended lamp does emit UV radiation below 300 nm. Keep in mind that his instrument was calibrated to pick up 310 nm and above. But it is clear from this chart that the lamp emits UV below that range:




Here is what Robert Fenner has to say on this topic on his site www.wetwebmedia.com

Shielding

Was just mentioned in thermal terms. Also of concern is life-damaging ultraviolet light produced. Real fast here; U-V light is classified into three types on the basis of wavelength. In nanometers these are:

UV A: 320-400 nm, UV B: 280-320 nm, UV C : 200-280 nm

Some UV "A" range is useful, necessary for some light-using life; "B" and "C" are dangerous/harmful. UV "C" is absorbed by the planet's celebrated ozone layer; within it's band, 257 nm is the energy produced by UV sterilizers. UV "B" can be halted by glass and water, is very destructive to nucleic acids (life) and photosynthetic activity. UV "A" is effectively filtered out for the most part by special filters and bulb coatings provided by manufacturers. I only will install and address the use of metal halides with the use of UV filters, even though they may coated/engineered to be used without them. This added protection against radiation poisoning may require more shielding action and periodic cleaning, but is well worth the "cost" in preventing you and your livestock from "burning". Also of concern is the explosive effect of these 'high-pressure' light sources getting splashed, broken by splashing water, or cumulative bubble-mist.