Actinic Lighting Safety

[pjf]

How safe is the actinic lighting that we use in reef aquaria? I am concerned with the early morning and late afternoon periods when the metal halides are off and the actinic fluorescents are the only lighting over the tank. The pupils of our eyes are quite dilated during these periods and are more vulnerable to UV radiation should any be emitted.

I am reminded of cheap sunglasses that do not block UV but do block enough visible light to dilate your pupils and leave your eyes more vulnerable to damage.

 

[billsreef]

They don't emit uv, so no worries

 

[DocApoc]

Wow, I posted a big response, and then I had doubts, and did a bunch of web searches, and now I'm re-writing my post.

Actinic lights do emit some UV, but not very much. Of course they emit some, that's why they make many corals flouresce. But looking at a spectrum of a "super actinic"

http://unblinkingeye.com/Articles/Light/UVC4/uvc4.html

it looks like very little will be <380nm - which is considered UVA light. Large amounts of UVA is harmful to eyes and skin.

Acording to Wikipediea:
Ordinary, untreated eyeglasses give some protection [from UVA]. Most plastic lenses give more protection than glass lenses, because, as noted above, glass is transparent to UVA and the common acrylic plastic used for lenses is less so.

so not much uv light, and the tank blocks most of it from coming out anyway.

 

[pjf]

<a href=showthread.php?s=&postid=8829244#post8829244 target=_blank>Originally posted</a> by DocApoc
so not much uv light, and the tank blocks most of it from coming out anyway.

The problem is not UV light coming through the tank glass. The problem is that actinic lamps are plainly visible above the aquarium. You can look directly at them. I've got high-output (55-watt) T6 lamps.

Where can I find more information? Thanks!

 

[pjf]

Ultraviolet Radiation and Aquarium Lighting

Ultraviolet Radiation and Aquarium Lighting

The information in this article by Dana Riddle, entitled “Ultraviolet Radiation and Aquarium Lighting,” is a bit disturbing: http://www.masla.com/reef/uvlighting.html.

Among his findings are:
• The glass envelops of MH lamps transmit most of the UV radiation produced.
• “Using a glass aquarium, we found UV-A levels of up to 70% being transmitted through the glass above the water surface.”
• “Under certain conditions, we believe this level of radiation could exceed that of natural sunlight.”

Comments, anyone?

 

[pjf]

MH Shields Transmit UV

MH Shields Transmit UV

Even shielded DE lamps transmit a lot of UV. Take a look at Dr. Joshi's spectral plots of shielded 250w DE lamps: http://www.advancedaquarist.com/issues/feb2004/feature1.htm.

Eyeballing the spectral plots, it looks like the shield only blocks ~30% of the UV. There is more ultraviolet than red or orange coming through the shields. In fact, there is a significant UVA peak at 360nm. This is true virtually across the board.

Short of going to LED lighting, what can be done?
Are there UV blocking sleeves that can be placed around tube lighting?
Is there more effective UV blocking glass that can be used as a shield?

 

[DocApoc]

It looks like you've done all the "easy" research. Anything else is probably going to get complicated. And your dealing with a dificult to measure effect.

The simplest solution would probably be to modify the hood so that the lights are not directly visible.

Any light that comes out of the hood isn't going into the tank where you want it anyway. Why not a bigger/deeper reflector?

 

[Spyogenes]

The UV light is a concern but a concern that I would have is that of the SHORT WAVE LENGTH BLUE light that you all are over looking. Beings as eyes are my profession the blue light can often times be more harmful to your eyes than UV. UV STILL IS A CONCERN but the blue is VERRRRYYYY damaging as well. So try to solve that situation so you keep your vision for many years to come, oh yeah and so you can see your cool fishes and corals too!!

Semper Fi
spyogenes

 

[pjf]

Actinic Fluorescent Lamps

Actinic Fluorescent Lamps

<a href=showthread.php?s=&postid=8929347#post8929347 target=_blank>Originally posted</a> by Spyogenes
The UV light is a concern but a concern that I would have is that of the SHORT WAVE LENGTH BLUE light that you all are over looking. Beings as eyes are my profession the blue light can often times be more harmful to your eyes than UV. UV STILL IS A CONCERN but the blue is VERRRRYYYY damaging as well.

I am not aware of the health impact of short wave length blue light. Your response is quite timely because I am considering the purchase of two 48" fluorescent T6 actinic lamps that claim to have a peak at 420nm. The link to the description of these lamps is: http://www.bigalsonline.com/BigAlsU...381683/cl0/quantum40wattblueactinic03t6lamp48

Any final advice before I make a purchase decision?
Are there any blue actinic fluorescent bulbs that are safe?
Any links to information that I can use to educate myself?

Thanks!

 

[rustybucket145]

This may be a dumb question but how does the level of UV produced by our aquarium lights compare to the levels of UV encountered everyday outside, produced by the sun?

For instance I have 2 175 Watt Metal Halides with 14k bulbs. I also have 2 VHO Actinic lights. How would standing under a setup like that compare to the UV encountered by standing outside for the same amount of time?

 

[pjf]

Exceeds Natural Sunlight Under Certain Conditions

Exceeds Natural Sunlight Under Certain Conditions

"Under certain conditions, we believe this level of radiation could exceed that of natural sunlight." - Dana Riddle (http://www.masla.com/reef/uvlighting.html)

 

[pjf]

UV Sensor Card

UV Sensor Card

Here's another article from Dana Riddle about UV: http://www.advancedaquarist.com/issues/aug2004/feature.htm. In the article, he recommends the use of a UV sensor card from Edmund Scientific: http://scientificsonline.com/product.asp_Q_pn_E_3120200.

I'm not sure how accurate these cards are but short of holding my arm underneath a lamp to see if it causes a sunburn, I'm not sure what my options are. The next time I buy a lamp, I'll insist on seeing the manufacturer's spectral plot and hope that wavelengths below 400nm are plotted.

Here's another thread on the Lighting/Filtration forum about UV from metal halide lamps that was joined by Dana Riddle: http://www.reefcentral.com/forums/showthread.php?s=&threadid=1035556.

 

[pjf]

Personal UV Sensor

Personal UV Sensor

I just bought this from Target today for $20.

It is a "Personal UV Sensor" from Oregon Scientific. It doesn't measure PAR but will give me a "UV Index." I'll take measurements of my lighting this weekend and post the results.

 

[pjf]

UV Index

UV Index

Here are some readings from the Oregon Scientific "Personal UV Sensor" that I bought from Target for $20:
<table border>
<caption>”Personal UV Sensor” Readings</caption>
<tr><th>SOURCE<th>DISTANCE<th>UV INDEX</tr>
<tr><td>Sunlight 11:00 am<td>7500’ elevation<th align="center">8</tr>
<tr><td>MH-HQI 150w<td>8”, 2 min after start<th align="center">2</tr>
<tr><td>MH-HQI 150w<td>8”, 10 min after start<th align="center">1</tr>
<tr><td>T6 40w<td>0”<td align="center">0</tr>
<tr><td>370nm UV LED<td>0”<td align="center">0</tr>
</table>

The “Personal UV Sensor” shows that there is UV emitted by my 150-watt metal halide lamps detectable just above the water’s surface 8 inches below the lamp shield. The UV intensity was twice as high during the first few minutes of startup than 10 minutes later. The sensor does not appear to be very sensitive. No UV emissions from the T6 and 370nm “Black Light” LED registered on the sensor.

Lamps vary within the same production lot. This is only one sample taken with a not very precise instrument.

 

[pjf]

Unshielded MH-HQI

Unshielded MH-HQI

Here is the updated table with two additional measurements obtained with the shield removed from the MH-HQI lamp:
<table border>
<caption>UV Index Readings (10-Feb-07)</caption>
<tr><th>SOURCE<th>DISTANCE<th>UV INDEX</tr>
<tr><td>Sunlight 11:00 am<td>7500’ elevation, snow<td align="center">8</tr>
<tr><td>T6 40w<td>0”<td align="center">0</tr>
<tr><td>370nm UV LED<td>0”<td align="center">0</tr>
<tr><td>Shielded MH-HQI 150w<td>8”, 2 min after start<th align="center">2</tr>
<tr><td>Shielded MH-HQI 150w<td>8”, 10 min after start<th align="center">1</tr>
<tr><td>Unshielded MH-HQI 150w<td>8”, 1 min after start<th align="center">10</tr>
<tr><td>Unshielded MH-HQI 150w<td>8”, 10 min after start<th align="center">9</tr>
</table>
The unshielded MH UV readings are higher than that of the Colorado sun at 7500 feet elevation with 2 feet of snow on the ground. I believe that what the "Personal UV Sensor" is measuring is UV-B or UV-C that is blocked by the UV shield. Here is a quote from Dana Riddle:

UV-C is also transmitted through the DE's double UV shield (shield those lamps for sure!).

(http://www.reefcentral.com/forums/showthread.php?s=&threadid=1035556&perpage=25&pagenumber=2)

Dana Riddle is referring to the two glass envelopes surrounding the arc of a DE bulb. Since UV-C penetrates these envelopes, the fixture's tempered glass UV shield is still required.

Here is a spectral plot by Sanjay Joshi that shows a UV shield blocking the UV-B spike at 320nm:

Source: http://www.advancedaquarist.com/issues/feb2004/feature1.htm