Moonlighting question

[inovrmyhd]

I have some 12v LED lights lying around that I was thinking about using for moonlights. I have 6 of them wired together and hooked to a 12v power supply that I also had lying around (I have a hard time throwing anything away). The lights are supposed to be purple but when I put them above my corals they glow like flourescent paint under a black light. It looks really cool but I was wondering if this would be bad for the corals (candy cane, 2 kinds of Zoas, misc shrooms and an Anemone). I was also wondering if anyone knew a trick to making the light defuse more. The LEDs are like spotlights and I wanted to make the light spread out more.

 

[DarG]

Not an LED expert but even the standard 3mm, 5mm, 10mm led's are designed to emit light with a certain viewing angle or spread. Some have wider angle than others. You probably could come up with some type of reflector that would spread the light out some more but the LED itself is still going to directly radiate the light at it's designed angle or degree of spread. If you made some type of mini reflectors that the LED was actually enveloped within then you could probably more effectively change the spread. Not sure it's worth the hassle. All the basic led's I have used for moonlighting (premade or came with a fixture) all were more light spotlights than floodlights. Im using a couple 3/4 watt blue LED's now that come in their own housing with reflector or some rudimentary optics that spread the light much better than the standard LED's. Two of them did a good job at "moonlighting" the entire tank. They are getting duller now though. They werent top quality LED's but they held up pretty well.

LEDs are a point source light afterall. Buy You can create more of a flood light effect if they are grouped together in multiples
rather than just running a linear string of LED's.

The LEDs you have sound like the ones they sell as UV led's. You can easily find them in the 395nm - 420nm range and lower as well with a little more searching. So depending on what you have, they can cause the blacklight effect which would accent coral flourescence and certian colors. Not sure what the cutoff is in nm for when the UV (UVC) light they emit can damage your eyes but they do make LED's in that range for medical and other uses.

 

[inovrmyhd]

I was thinking of actually making a fixture with the lights pointing up to a dimpled reflector so it would reflect at different angles. I don't want to put the work into it if the lights will cause damage though. Hopefully someone will know if I can use them because it looks really cool.

 

[DarG]

I doubt that the LED's you have will cause any damage. They are probably in the 400nm range or maybe a little lower judging from your description. If they are giving off the violet/purple light, the description would suggest that they are in that range. The same as the 420nm actinic VHO or T5 or maybe a little lower. Even some halides have some output in that range.
But they usually tell you the wavelength of the LED, do you know or remember what it is?

If you direct the light upwards to a refector, it will definitely widen the spread but the light will be more diffuse so you may need more LED's to have a bright enough overall effect. Depends what you want.

I never wanted mine to lighten the tank enough that I could actually view everything from where we normally sit. I just use them to create a low glow. We can look at the tank up close and see what the nocturnal critters are doing but not light the entire tank so we can see everything from the couch. I only use them in the morning for a couple hours and at night for a couple hours before and after the flourescents go on and off. More for the cool blue glow and for us than for the tank. But again, depends what you want. There really isnt any right or wrong for "moonlighting" unless they are so bright that the tank never gets a true night period or using some type of UVC emitting LED.

 

[kentlighting]

Im a lighting Designer for concerts, and we have stuff called Frost Gel to help spread light out more. Any local theatrical supply house will carry it. The one thing to consider is that you are taking the same amount of light and spreading it across a wider area and you are you are putting more material between the source and the object being lit so the brightness will decrease. There are varying levels of frost gel from light to heavy frost. ask for a swatch book which will have samples of the different gel and hold them up to one of the light sources and see what works for you. A sheet of gel (2'x2 1/2' roughly) will cost you no more than 10 bucks and you can cut it to what you need.

 

[inovrmyhd]

Thanks Will. I'll look into that. My wife used to do sound and lighting in college so she may know where to get it.