# Actinic lights



## frozenoak (Jul 30, 2005)

Does actinic lighting do anything for the planted freshwater aquarium?

dale


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## RoseHawke (Jan 4, 2005)

It looks pretty . My understanding is it puts light out in the wrong part of the spectrum for FW plants to properly utilize. I'm sure someone will be along that can explain it in more depth.


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## Salt (Apr 5, 2005)

This is one of those topics that always makes me cringe when I see it, mainly because the threads typically get filled up with a lot of replies along the lines of "it does nothing," "they are for saltwater tanks only," etc., yet I am willing to bet good money that these people are just repeating what they've heard someone else say without any firsthand experience. (This is not a directed at you Cindy. )

In my *own testing*, I have found that actinic lighting alone of course is not adequate at all for most species of aquatic plants. For example, cabomba will sort of "roll up" its leaves when the lights go out, and "fan out" its leaves when the lights go on. With actinic lights, cabomba will keep its leaves "rolled up."

However, actinic lights actually improve conditions for plants when they are used _in addition to_ main lighting, as supplemental lighting. Plants _do use_ light in that part of the spectrum. It also creates a much more natural look to a tank, as actinic lights simulate the backdrop of a blue sky. I am confident saying this because it's something I actually tested myself. If you get the AGA 2001 Convention DVD, there is a speaker on there who also tested this and got the same results.

I would *not* include them when calculating how much light you'd put over your tank. For example, if you have a 40 gallon tank, and a light fixture that takes two 40W PC bulbs, I would *not* use an actinic bulb for one of the lights. I believe they should be added _after_ full spectrum requirements are met.

In my own tank, I have a metal halide / power compact pendant fixture that uses a 150W metal halide bulb. I have two 32 W actinic bulbs in for the PC lights.


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## frozenoak (Jul 30, 2005)

Thank you for the replies. I am not sure what actinic light is intended to do. I had always thought that they were for the fish. (or the coral which is an animal I believe) 

I hadn't really thought to use them but I change them when they come with a hood and am beginning to wonder if I could leave them in. 

Do they help the color of the fish?

dale


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## Moo (Apr 27, 2006)

Yes, in freshwater aquaria the bring out colors waaay more than normal 6700k or 100000k bulbs. As said above also the plants use "some" of the light it seems. I have 110 watts of CF lighting over my 55 gal and just around 30 watts of actinic light. 
I just think it looks better. 
Some people say it increases the probability of algae but I've had no problem.

It just brings out colors better.
Also as said above don't add the wattage of the actinic light in with normal lighting.


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## frozenoak (Jul 30, 2005)

I was afraid to post this questions for reasons that Salt mentioned. I appreciate the well explained answers. One other question i am left with is this: I have a 2g cube and a Coralife hood that houses 2 9w lights. I have in my possession 1 6700k bulb, 1 10,000k bulb and 1 actinic bulb. How would you use these bulbs?


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## Salt (Apr 5, 2005)

frozenoak said:


> I am not sure what actinic light is intended to do. I had always thought that they were for the fish. (or the coral which is an animal I believe)


Deep bodies of water look blue because the light spectrum is not absorbed equally by water. Red and green get absorbed relatively quickly, while blue is able to penetrate much deeper into the water.

Coral reefs are typically in 15 - 30 feet deep water, where most of the red and green light has been absorbed. Since aquariums are not that deep, the actinics are intended to compensate for this by providing blue light.


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## Moo (Apr 27, 2006)

> I have a 2g cube and a Coralife hood that houses 2 9w lights. I have in my possession 1 6700k bulb, 1 10,000k bulb and 1 actinic bulb. How would you use these bulbs?


Well since using just one bulb would put you at almost 5 wpg I would use either the 6500k or the 10000l and then possibly the actinic.

Hopefully will help me either way but this seems logical to me, but I have been wrong. lol

-moo


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## Endler Guy (Aug 19, 2007)

frozenoak said:


> Does actinic lighting do anything for the planted freshwater aquarium?
> 
> dale


It started turning my Marble Queen Radican Swords red only a few hours after using it. This just happened this morning when I decided to use the 2 65 watt actinics that came with my fixtures. I'm now hoping they will help my bronze and red crypts to start growing.


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## hoppycalif (Apr 7, 2005)

frozenoak said:


> I was afraid to post this questions for reasons that Salt mentioned. I appreciate the well explained answers. One other question i am left with is this: I have a 2g cube and a Coralife hood that houses 2 9w lights. I have in my possession 1 6700k bulb, 1 10,000k bulb and 1 actinic bulb. How would you use these bulbs?


I used a 2.5 gallon tank for several months, with a 27 watt CF bulb desk light to light it. That gave very slow growth in the tank. So, I think you will do best to use the non-actinic bulbs so you have enough light. For tanks that small the 2 watts per gallon rule is way, way off.


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