UV light question

ntfish · 02/04/2007, 10:51 PM

Some halide bulbs come with a uv filter and some don't. Is uv harmful to corals? Do you need to place some sort of filter or glass with lead in it's content over the bulbs that don't have a filter? Thanks.

hahnmeister · 02/04/2007, 11:19 PM

UV-C or short-wave UV is deadly to everything, but also the easiest to block... regular glass blocks it pretty well. Water filters it in the top few inches as well.

UV-B is debatable... I would imagine shallower water species dont mind, and clams could care less (perhaps color in better with it). I would imagine its a good light as long as its not alot, which, fortunate for us, bulbs that do make it dont make alot. Water filters out UV-B pretty quickly in the upper layers... so who knows.

UV-A is a good UV for corals. Some bulbs like the Giesemann True Actinic 03 put out UV-A on purpose. It really can bring out the colors in some corals. Of all the UV, this is the easiest and most common, er, rather abundant of what bulbs that make UV produce. The one exception would be a germacidal or UV-C bulb which is made to produce UV-C. Blacklights are an example of UV-A light.

About the sheilds... ALL halide bulbs have a UV sheild. Mogul bulbs have the sheild built on to the bulb itself. DE bulbs are less bulky because they usually dont have a UV-sheild built in. This is why they have to have a sheild as part of the fixture.

ntfish · 02/05/2007, 03:27 AM

You answered my questions quite well. Thanks.

hahnmeister · 02/05/2007, 01:51 PM

In case you didnt see it already... a nearly identical thread...
http://reefcentral.com/forums/showth...02#post9163302

pjf · 02/17/2007, 08:49 AM

Quote:

Originally posted by hahnmeister
UV-A is a good UV for corals. Some bulbs like the Giesemann True Actinic 03 put out UV-A on purpose. It really can bring out the colors in some corals. Of all the UV, this is the easiest and most common, er, rather abundant of what bulbs that make UV produce.

hahnmeister,

You and Bean Animal had both expressed that UV-A can be beneficial to corals. I'd like to do some more reading on the subject and would appreciate it if you would be able to supply me with:
- Links to information about the benefits of UVA to corals.
- Links to spectral plots of the Giesemann True Actinic 03 lamp.

Thanks!

pjf · 02/17/2007, 12:32 PM

This looks like the spectral plot of the Giesemann Powerchrome â€œPure Actinicâ€ T5:

Source: http://www.giesemann.de/79,2,,.html

Can one actually see corals fluoresce with this T5HO lamp? I normally use a keychain-size 370nm LED for brief nighttime viewing of coral fluorescence. I would think that the brightness of the visible portion of this lamp will overpower our ability to see coral fluorescence.

It certainly produces UV-A (320nm-400nm). I'd like to see the plot extended down to UV-C as low-pressure mercury emits most of its radiation at 254nm and 185nm.

If anyone has any links to information regarding the benefit of UV-A radiation to corals, I would appreciate it. Thanks!

hahnmeister · 02/17/2007, 01:15 PM

http://www.advancedaquarist.com/2006/9/aafeature

No, we cant see UV-A, but it excites specific pigments in some corals it seems, and we see these colors back as purple. FWIW, a blacklight is a UV-A bulb, and we all know what effect blacklights have on certain colors. So while we dont see UV-A directly, it has its effect.

pjf · 02/17/2007, 02:23 PM

Iâ€™m not asking if we can see â€œblack lightâ€ or UV-A. Iâ€™m asking if anyone using aquarium actinic lamps, such as the Giesemann â€œPure Actinicâ€ T5, can actually see anything fluoresce. Normally, the dim fluorescent emissions are washed out by visible light. For example, a fluorescent poster can look plain under black light unless the room is dark.

In a dark room, my anemone will glow green under my UV-A LED. When the room lights are turned on, it appears yellow-brown. I have minerals, rocks, and â€œinvisible inkâ€ that under UV-A will glow bright yellow, orange, red and blue. These fluorescent colors are only visible in a dark room under UV-A. If the room lights are on, these colors are washed out. A rock that is bright red under UV-A in a dark room will turn grey when the room lights are turned on.

hahnmeister · 02/18/2007, 12:50 PM

I have two G-mans over my 40B, and yes, I can see things 'pop' even when my daylight bulbs are on. It prolly has to do with the relative amounts of the various light wavelengths. IF that UV-A light that was illuminating the rocks was say... 1000 watts rather than just 10watts (as an example), and could compete with the output of the other daylight bulbs, then I would imagine the rocks would still glow even when the other lights in the room are turned on.

pjf · 02/18/2007, 10:42 PM

Quote:

Originally posted by hahnmeister
I have two G-mans over my 40B, and yes, I can see things 'pop' even when my daylight bulbs are on. It prolly has to do with the relative amounts of the various light wavelengths. IF that UV-A light that was illuminating the rocks was say... 1000 watts rather than just 10watts (as an example), and could compete with the output of the other daylight bulbs, then I would imagine the rocks would still glow even when the other lights in the room are turned on.

The best way to verify fluorescence is with "Black Light" (UV-A) in a dark room. Otherwise the colors that you are seeing may be due to reflected visible light and not due to fluorescence. The Giesemann lamps do produce a great deal of visible light.

I do not recommend a 1000-watt "Black Light." A simple keychain-size UV-A LED, such as those used at money counters, will work. Even these small 370nm LED's come with health warnings.

Just as one cannot see chlorophyll fluorescence in broad daylight, it is unlikely that one can see coral or anemone pigments fluoresce under aquarium â€œactinicâ€ lighting. You need a small UV-A source and a dark room.

hahnmeister · 02/18/2007, 11:29 PM

Okay, I must not have understood... you are asking what the results would be if someone placed a blacklight over their tank? Is that it?

pjf · 02/19/2007, 07:31 AM

Quote:

Originally posted by hahnmeister
Okay, I must not have understood... you are asking what the results would be if someone placed a blacklight over their tank? Is that it?

Not exactly. I've seen the results from the blacklight LED that I've used over my tank for brief periods. I cannot see that same fluorescent color with aquarium lighting because of the visible light that will wash out any fluorescent color. For example, one of my anemones glows green under blacklight in a dark room. With the actinic lamp, it looks yellow-brown. Another anemone also glows green under UV-A but is white and purple under normal lighting.

Has anyone done the following?
(1) Use a blacklight in a dark room to view coral or anemone fluorescent coloration
(2) Use an actinic lamp and note if the same fluorescent color is visible under the actinic lamp.

If so, please post:

- The brand and model of the actinic lamp that you used
- The color of the fluorescence you saw under both the blacklight and the actinic lamp.

Thanks!

hahnmeister · 02/19/2007, 02:06 PM

I should have a blacklight around here somewhere... a 4' unit no less... I wonder where I put it...

Its only 40 watts, but I can try it and let you know... maybe even take pics.

02/04/2007, 10:51 PM	#1
ntfish Registered Member Join Date: Nov 2006 Location: Nebraska Posts: 95	UV light question Some halide bulbs come with a uv filter and some don't. Is uv harmful to corals? Do you need to place some sort of filter or glass with lead in it's content over the bulbs that don't have a filter? Thanks.

02/17/2007, 12:32 PM	#6
pjf Premium Member Join Date: May 2005 Location: Colorado Posts: 2,954	Giesemann Powerchrome â€œPure Actinicâ€ T5 This looks like the spectral plot of the Giesemann Powerchrome â€œPure Actinicâ€ T5: Source: http://www.giesemann.de/79,2,,.html Can one actually see corals fluoresce with this T5HO lamp? I normally use a keychain-size 370nm LED for brief nighttime viewing of coral fluorescence. I would think that the brightness of the visible portion of this lamp will overpower our ability to see coral fluorescence. It certainly produces UV-A (320nm-400nm). I'd like to see the plot extended down to UV-C as low-pressure mercury emits most of its radiation at 254nm and 185nm. If anyone has any links to information regarding the benefit of UV-A radiation to corals, I would appreciate it. Thanks!

02/17/2007, 02:23 PM	#8
pjf Premium Member Join Date: May 2005 Location: Colorado Posts: 2,954	Fluorescence visible in daylight? Iâ€™m not asking if we can see â€œblack lightâ€ or UV-A. Iâ€™m asking if anyone using aquarium actinic lamps, such as the Giesemann â€œPure Actinicâ€ T5, can actually see anything fluoresce. Normally, the dim fluorescent emissions are washed out by visible light. For example, a fluorescent poster can look plain under black light unless the room is dark. In a dark room, my anemone will glow green under my UV-A LED. When the room lights are turned on, it appears yellow-brown. I have minerals, rocks, and â€œinvisible inkâ€ that under UV-A will glow bright yellow, orange, red and blue. These fluorescent colors are only visible in a dark room under UV-A. If the room lights are on, these colors are washed out. A rock that is bright red under UV-A in a dark room will turn grey when the room lights are turned on.

02/04/2007, 11:19 PM	#2
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	UV-C or short-wave UV is deadly to everything, but also the easiest to block... regular glass blocks it pretty well. Water filters it in the top few inches as well. UV-B is debatable... I would imagine shallower water species dont mind, and clams could care less (perhaps color in better with it). I would imagine its a good light as long as its not alot, which, fortunate for us, bulbs that do make it dont make alot. Water filters out UV-B pretty quickly in the upper layers... so who knows. UV-A is a good UV for corals. Some bulbs like the Giesemann True Actinic 03 put out UV-A on purpose. It really can bring out the colors in some corals. Of all the UV, this is the easiest and most common, er, rather abundant of what bulbs that make UV produce. The one exception would be a germacidal or UV-C bulb which is made to produce UV-C. Blacklights are an example of UV-A light. About the sheilds... ALL halide bulbs have a UV sheild. Mogul bulbs have the sheild built on to the bulb itself. DE bulbs are less bulky because they usually dont have a UV-sheild built in. This is why they have to have a sheild as part of the fixture.

02/05/2007, 03:27 AM	#3
ntfish Registered Member Join Date: Nov 2006 Location: Nebraska Posts: 95	You answered my questions quite well. Thanks.

02/05/2007, 01:51 PM	#4
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	In case you didnt see it already... a nearly identical thread... http://reefcentral.com/forums/showth...02#post9163302

02/17/2007, 01:15 PM	#7
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	http://www.advancedaquarist.com/2006/9/aafeature No, we cant see UV-A, but it excites specific pigments in some corals it seems, and we see these colors back as purple. FWIW, a blacklight is a UV-A bulb, and we all know what effect blacklights have on certain colors. So while we dont see UV-A directly, it has its effect.

02/18/2007, 12:50 PM	#9
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	I have two G-mans over my 40B, and yes, I can see things 'pop' even when my daylight bulbs are on. It prolly has to do with the relative amounts of the various light wavelengths. IF that UV-A light that was illuminating the rocks was say... 1000 watts rather than just 10watts (as an example), and could compete with the output of the other daylight bulbs, then I would imagine the rocks would still glow even when the other lights in the room are turned on.

02/18/2007, 11:29 PM	#11
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	Okay, I must not have understood... you are asking what the results would be if someone placed a blacklight over their tank? Is that it?

02/19/2007, 02:06 PM	#13
hahnmeister Moved On Join Date: Sep 2005 Location: Brew City, WI Posts: 10,156	I should have a blacklight around here somewhere... a 4' unit no less... I wonder where I put it... Its only 40 watts, but I can try it and let you know... maybe even take pics.