# Question about light



## jeffro0050 (Apr 4, 2010)

This may be a very dumb question, but here goes.

I know that UV light can not penetrate glass- my 55 gallon's top has transparent sheets where a strip light is designed to fit (that I now have to build).

Does this affect light quality getting to the plants? If not, would it not be more efficient in a DIY hood to have the lights extremely close to the water and protected against water splashes by something transparent?


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## medlii (May 13, 2010)

I don't know a lot about aquarium plants but I do know about plastics. Is the transparent sheet flexible or rigid? If it's rigid, it's probably plexiglass, if it's flexible, I'll try and figure out what else it could be.

Your transparent sheet is probably poly methyl methacrylate, commonly known as plexiglass. According to Wikipedia, it filters similar wavelengths of light that glass does, meaning that your plants are getting the same amount of light through it as they would if it were glass.

It doesn't really help to have the lights closer to the plants- just a few inches of height won't make much of a change to how much light the plants are getting.


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## jeffro0050 (Apr 4, 2010)

hmm, interesting. So I can assume that plastic coverings on lights are a bad thing because it filters out higher wavelengths? Or am I mistaken in that regard?


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## medlii (May 13, 2010)

I'm honestly not sure what kind of light is most beneficial for aquatic plants. I did a google search and got conflicting results  Some said that UV light kills plants, just like it kills most living things. Others said that plants do need UV. I'm sorry I couldn't be more helpful!


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## NursePlaty (Feb 5, 2010)

*My friends 100 gallon has a strip of glass where the light is supposed to sit on too. Its supposed to prevent splashing of water to the light. This DOES block some light that reaches the plants same way as a window blocks sunlight. If you dont have any big fish that like to splash you can remove the glass like my friend did but if you do I suggest you leave the glass there. You wouldnt want to short circuit your fish . Dont know if I answered your question or not.*


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## jeffro0050 (Apr 4, 2010)

Well, I don't intend to keep arrowanas or anything like that, but I may actually keep larger gouramis that do indeed stay very close to the surface... I guess the best answer I'm in need of is whether or not there's any REAL benefit to getting the lights as close to the water as possible, or if keeping them at safe distance and using reflective white paint is better.

Still though, I appreciate the input. Doing a massive hood build and want to make sure it is as good as I can make it.


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## WhiteGloveAquatics (Sep 3, 2009)

what lights do you have or want to go with?

One tank of mine has a 36" coralife T5HO 39wx2 fixture on it just inches off the water and my 210 has a sun system TEK light with 8x80w 60" bulbs in it however this light is suspended 15" above the water surface and I still get 2-3" of light penetration INTO the substrate.

I also have open top tanks and dont have to deal with this issue.
The distance doesnt seem to matter really. I also got Co2 on my tanks and dose with micros and macros so I cant single out if its better or not. I do know my repens in my 210 have grwon 4" in less then 6 days.


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