Ultra violet for SPS

[TekCat]

I had a thought (..I know, its scary when I have one ). Some SPS corals have coloration (beside brown) for UV ray's protection. In our tank we don't (or do we?) have enough UV radiation falling down on the corals to mimic their natural habitat. Did anyone experimented with black light or UV leds supplementation?

 

[acroman]

ive used blacklight with some success, but you really need a pc blacklight to have any great effects. also, if you need a mix of UV-A and UV-B, and im not sure if normal blacklights provide both.
regardless, the corals need enough energy to produce the costly pigments, so if you are going to increase the UV to produce more color, make sure you feed the colonies

 

[TekCat]

which bulbs did you use?

 

[acroman]

i used a 40W flourescent on a 55 gallon tank.

 

[pjf]

Plenty of UV from MH Lighting

Plenty of UV from MH Lighting

Since the UV “sunscreen” produced by corals is colorless, it’s tough to show that coral coloration is due to UV. Dana Riddle states (http://www.masla.com/reef/uvlighting.html): “Our experiences indicate that some corals will turn green as a response to increased UV. However, we have observed many corals (especially Acroporids, Pocilloporids, etc) exhibiting vivid coloration when maintained for years under conditions of practically no UV (~1 µW UV-A; <1 µW UV-B).” Riddle goes on to say that there may be more UV in our aquariums than in nature.

If you want UV, both SE and DE metal halides will produce plenty of it despite the “UV shields.” Riddle’s article cited above shows that the outer glass envelopes of SE bulbs transmit most of the UV produced. Any of Dr. Joshi’s spectral analyses will show that plenty of UV is emitted by MH bulbs. Just look to the left of the 400nm point on his spectral plots. If you remove the UV shield of a DE bulb, you will get a UVB peak at 320nm (http://www.advancedaquarist.com/issues/feb2004/feature1.htm). Even with the shield, there is plenty of UVA.

 

[daytonians]

Another thing to consider. UV light is very hard on human eyes. It is believed to be the main cause of cataracts. I wonder if it would be safe looking into a tank with UV bulbs on a daily basis.

 

[el chupacabra]

Just for the record a black light such as the one you would get at walmart to make stuff glow, is just a purple (violet) light. Its pupose is not to make any more UV than any other flourecent bulb. If you read the boxes they say "ouputs light at near UV."

If you put one of these over your corals and they flourece then your corals are getting enough if not too much violet/UV. The glowing is a defence mechanism against high energy wavelengths; so if your coral glows under your normal lighting or a simple black light it wouldn't make sence to me to add an even higher energy wave length light.



this picture shows what light colors (wave lengths) plants use most (blue and red)

 

[musty baby]

By "near uv" it doesn't mean the light is nearly UV, it means the UV is in the range near visible light.
Black light output is nearly all UV.

...and flourescence is no more a defense mechanism with corals as it is a defense mechanism for your white Tshirt at midnight bowling.

 

[daytonians]

Ryansholl is correct. Near UV is ultra violet near the visible spectrum.

 

[TekCat]

So, since black light is not quite UV than is it safe to use? Does anyone have any info on spectrum of black light and its intensity?

 

[daytonians]

This was posted on a vendor's website. He sells black light bulbs like the ones discussed here. They put out UV-A.

quote
"Since we have no desire to sun tan our eyeballs, I suggest sticking to the 345 to 400 nm range. But just because a light source is UV-A does not mean that it is completely safe. It just means that it is safer than the really nasty flavors of UV. UV-A can still cause damage and must be used judiciously.

Also, be aware that intense light of any wavelength can damage your eyes, and since UV is not visible, you might be getting a damaging dose and not even know it. "