# Actinic/blue lights and plants...



## Cinbos (Dec 8, 2012)

I came across a post on a Facebook group where someone mentioned that plants eat up blue lights and they will do just fine, Is this true?

The post came about when a newbie asking if actinic bulbs will do ok with plants (they had these lights from their previous reef tank). Another person proceeded to say that actinic lights would be just fine and plants eat blue up on the color spectrum. I never heard this and it came as a shot to me.

They also went as far as saying that one could light their planted tank with just actinic bulbs, and the plants would be fine.


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## Bluek24a4 (Mar 16, 2010)

I had good growth when I tried an actinic bulb out for myself. The color though is not the most flattering for a planted tank.


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## wheeling (May 6, 2013)

This is not true. Plants need both blue and red lights to grow healthily. It may work for a short time but in the long run, plants will suffer.


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## Cinbos (Dec 8, 2012)

wheeling said:


> This is not true. Plants need both blue and red lights to grow healthily. It may work for a short time but in the long run, plants will suffer.


Thats what I thought!


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## seandelevan (Sep 24, 2006)

I was at a LFS a few weeks ago that had a pretty stunning planted tank. When I looked under the hood I was surprised to see actinic bulb mixed with two other bulbs that looked to be 6700k. I was impressed with how the tank looked.


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## FlyingHellFish (Nov 5, 2011)

Kind of true, but.....

You can have a white light that peaks in different spectrums, it's not just what you see with your eyes.

Aquatic plants use both blue and red, more so on the red spectrums. It's 400nm (blue) and 650nm (red), they use the most around the 650 nm - 680 nm. You can see the result with the Green colour they reflect back. Now if you have a lot of light in the red spectrum, some plants reflect that back because you're providing the plant with more light than they need. 

You can also have a light source that lacks the desire spectrum but make up for it with a higher intensity. This is usually in special cases such as a extremely deep tank. Then you need something like a Mercury vapour lamp. 

In my opinion, it's better to have a bulb that provides those desire wave length and another bulb for brightness, rather than just increasing the light to make up for the spectrum. There is a light threshold, you can't force plants to grow at speeds they're not used to. 

Less light also makes everything easier.... Less light in the right spectrum that is.


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## AndreyT (Apr 28, 2011)

The very fact that plants look _green_ under white light immediately indicates that plants consume (absorb) light in red and blue portions of the spectrum. This naturally makes one expect that blue-only light might be sufficient to sustain the plants. In fact, all plants have the type of chlorophyll that uses blue light in photosynthesis. It is just a matter of how efficient it will be compared to full spectrum light. And that efficiency might drop rather rapidly as the tank gets taller (deeper) since blue end of the spectrum has notably worse water penetration characteristics than the red one.


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## Adrand (Feb 13, 2012)

For the past year I had a 2 bulb t5NO fixture over my 20long tank. Bulbs were 6700 and actinic. No co2. Everything (vals, rotala, xmas moss, swords, anubia) has grown with no problem. Im constantly trimming the rotala and moss. Just this week I swapped out the actinic for a 10000k. We will see if it make a difference. Im not suggesting everyone should start using actinic but it seemed to provide something of use to my plants. I dont think I would be getting that much growth off a single t5no bulb. I will be interested to see the difference in growth with the new bulb though. 

Sent from my SPH-L720 using Tapatalk 2


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## Hoppy (Dec 24, 2005)

AndreyT said:


> ....And that efficiency might drop rather rapidly as the tank gets taller (deeper) since blue end of the spectrum has notably worse water penetration characteristics than the red one.


If this were true the light you see as you swim down deeper in the water would increasingly be red. But, we all know it isn't. It is blue. That is because red light is absorbed more strongly by water than blue, and below a certain depth there is too little red light left for our eyes to notice it. This is also complicated by the fact that human eyes are not very good at seeing red light, compared to how we see green, and to a lesser extent, blue light. 

One of these days some of us will get so curious about this subject that we will do some good experimenting with different color light on planted tanks. We will have tanks, otherwise identical, each with identical PAR, but different color light. We will then have data on the aquatic plant growing abilities of the different colors of light. There are many, many different tests that could be done this way, and it would be extremely interesting and informative.


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## Hoppy (Dec 24, 2005)

Adrand said:


> For the past year I had a 2 bulb t5NO fixture over my 20long tank. Bulbs were 6700 and actinic. No co2. Everything (vals, rotala, xmas moss, swords, anubia) has grown with no problem. Im constantly trimming the rotala and moss. Just this week I swapped out the actinic for a 10000k. We will see if it make a difference. Im not suggesting everyone should start using actinic but it seemed to provide something of use to my plants. I dont think I would be getting that much growth off a single t5no bulb. I will be interested to see the difference in growth with the new bulb though.
> 
> Sent from my SPH-L720 using Tapatalk 2


When doing this type of test you have to also make sure the PAR seen by the plants is very nearly the same, for the different bulbs being used. Otherwise, the results may mean nothing.


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## Steve001 (Feb 26, 2011)

Cinbos said:


> I came across a post on a Facebook group where someone mentioned that plants eat up blue lights and they will do just fine, Is this true?
> 
> The post came about when a newbie asking if actinic bulbs will do ok with plants (they had these lights from their previous reef tank). Another person proceeded to say that actinic lights would be just fine and plants eat blue up on the color spectrum. I never heard this and it came as a shot to me.
> 
> They also went as far as saying that one could light their planted tank with just actinic bulbs, and the plants would be fine.


Plants do use blue light but only a certain range of it. Wavelengths higher than about 450nm are useless. You can check this on the web. So what you need to know is precisely what this actinic or any blue emitting bulb's wavelength range is. As for plants doing well with just blue light that is somewhat BS-ing. They will grow yes and it will affect how they grow too.


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## Steve001 (Feb 26, 2011)

Adrand said:


> For the past year I had a 2 bulb t5NO fixture over my 20long tank. Bulbs were 6700 and actinic. No co2. Everything (vals, rotala, xmas moss, swords, anubia) has grown with no problem. Im constantly trimming the rotala and moss. Just this week I swapped out the actinic for a 10000k. We will see if it make a difference. Im not suggesting everyone should start using actinic but it seemed to provide something of use to my plants. I dont think I would be getting that much growth off a single t5no bulb. I will be interested to see the difference in growth with the new bulb though.
> 
> Sent from my SPH-L720 using Tapatalk 2


What's the range of wavelengths this bulb emits. This is something you needs to known.

Seeing how you used 6700k plus actinic shouldn't cause you to claim actinics are ok for plant growth.


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## FlyingHellFish (Nov 5, 2011)

Here a post I made in another thread... pretty much the same issue with lights and how we "see" it.

There are different levels of light intensity along a water source (river, lake, etc) you can look at the various different plants and see how they adapt to the environment. It just depends on what the hobbyist wants, you can have lust growth and great colour at a reasonable light intensity because you compensate with the ideal light spectrum. Then you have more control over your parameters like Co2 and fertilizers. Likewise, you can have a strong light that lacks the ideal spectrums but makes up for it with intensity. But now, you have to manage a higher level of light. An example would be a Mercury vapour lamp. 

There is a difference between what plants' need and what you want. It's better to have the right spectrum then to increase light intensity, basically. 


Steve001 - Aquatic Plants and algae do use the blue spectrums, but plants use more red light in the 650nm - 680nm range.


Steve001 said:


> Plants do use blue light but only a certain range of it. Wavelengths higher than about 450nm are useless. You can check this on the web.



Hoppy, you use got your par meter?


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## Adrand (Feb 13, 2012)

Steve001 said:


> What's the range of wavelengths this bulb emits. This is something you needs to known.
> 
> Seeing how you used 6700k plus actinic shouldn't cause you to claim actinics are ok for plant growth.


Sorry i wasnt trying to make any sweeping conclusions on the use of actinics in all planted tanks, I simply shared my own experience with actinic and like I said dont suggest we all head out to buy them. I agree that using the 6700 in addition to the actinic makes it difficult to know if it really was doing anything for the plants but I would be surprised if I would get that much growth from a single 18w t5 alone. Again pure speculation on my part. On the topic of algae, I read previously people suggesting an actinic bulb would cause horrible algae in a planted tank but I can say for the past year ive had nearly zero algae in this tank. I am interested to see how the change to a 10000k bulb will affect my algae and plant growth experience of the past year. 

Sent from my SPH-L720 using Tapatalk 2


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## jeffkrol (Jun 5, 2013)

AndreyT said:


> And that efficiency might drop rather rapidly as the tank gets taller (deeper) since blue end of the spectrum has notably worse water penetration characteristics than the red one.


Actually , as posted, that is backwards... Red is rapidly absorbed in water..blue not so much


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## FlyingHellFish (Nov 5, 2011)

Adrand, you did nothing wrong. It's good that people share their experiments and experience because we all can come to our conclusions. 

One of the reason why people avoid marine lights is because it provides a spectrum more useful to algae. It peaks in the blue 400 nm range with barely anything else. 
Which isn't necessary a bad thing, if you have a balance system with healthy plants you could avoid algae, it's just make it harder. 

Guys, we're putting way too much thought into this. The average hobbyist need not think about weird spectrums, leave that to the plant farmers. You can do fine with a light source that peaks in blue 400nm and red 650nm. Anything higher than 700nm, we're talking infrared light range here, aquatic plants can't use. . There is probably someone out there using Actinic lights and having great growth. But he could be pushing high Co2, rich substrate, daily algae cleaning, you just can't make a solid conclusion from that one tank. 

There just so many variables to consider, the only system we can look at is mother nature's own aquarium and draw from that.


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> Adrand, you did nothing wrong. It's good that people share their experiments and experience because we all can come to our conclusions.
> 
> One of the reason why people avoid marine lights is because it provides a spectrum more useful to algae. It peaks in the blue 400 nm range with barely anything else.
> Which isn't necessary a bad thing, if you have a balance system with healthy plants you could avoid algae, it's just make it harder.
> ...


now you tell me..


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## Hoppy (Dec 24, 2005)

FlyingHellFish said:


> .....Hoppy, you use got your par meter?


I'm sorry, but I don't understand the question.:icon_redf


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## FlyingHellFish (Nov 5, 2011)

Hoppy - Just wondering if you had a par meter because I was interested in the reading for some common CFL. Those home depot reflectors are wide, most common desktop lamp reflectors are narrower, was wondering how much more PAR it produces. 

jeffkrol - I just did, if you got lights that have those spectrums you should be fine. There is a book by Peter Hiscock that goes over the spectrum parts. And yes,it's a published book.


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## Adrand (Feb 13, 2012)

Adrand said:


> Sorry i wasnt trying to make any sweeping conclusions on the use of actinics in all planted tanks, I simply shared my own experience with actinic and like I said dont suggest we all head out to buy them. I agree that using the 6700 in addition to the actinic makes it difficult to know if it really was doing anything for the plants but I would be surprised if I would get that much growth from a single 18w t5 alone. Again pure speculation on my part. On the topic of algae, I read previously people suggesting an actinic bulb would cause horrible algae in a planted tank but I can say for the past year ive had nearly zero algae in this tank. I am interested to see how the change to a 10000k bulb will affect my algae and plant growth experience of the past year.
> 
> Sent from my SPH-L720 using Tapatalk 2


I just wanted to follow up on my previous post and experience. I have now switched the 1 actinic bulb in my dual t5no fixture to a 10000k (I didnt change the 6700k that was already in there). I have noticed a few changes since. First my xmas moss and frogbit have exploded in growth much beyond thev rate it was growing at before. Both are trying to take over my tank. Unfortunately my vals and anarchis have all but melted away. Rotala, anubia, and swords dont seem affected at all, one way or the other. Still no algae in the tank. 
Ill leave everyone to make their own conclusions on what these changes say about actinic lighting in a planted tank. I will say the coloration is much more pleasing to my eye now but I will miss my vals though....


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## Hoppy (Dec 24, 2005)

deleted


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## Cthulhu (Dec 18, 2012)

I am using my old reef lighting for my 95g. When the actinics are on it just doesn't look good at all, that much blue doesn't go well with the plants. So I just don't use the actinics, and the plants do very well. I have no idea what is the spectrum of the lights I am actually using.


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## Cthulhu (Dec 18, 2012)

I don't understand when people say that certain light wavelengths can promote algea. As far as I know, algea have the same kinds of chlorophyll as plants, and so use the same parts of the light spectrum. Maybe I am missing something there?


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## TexasCichlid (Jul 12, 2011)

Cthulhu said:


> I don't understand when people say that certain light wavelengths can promote algea. As far as I know, algea have the same kinds of chlorophyll as plants, and so use the same parts of the light spectrum. Maybe I am missing something there?


Algae tends to be more adaptive at making use of spectrum outside of what is typically used by plants is my understanding.


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## jeffkrol (Jun 5, 2013)

Cthulhu said:


> I don't understand when people say that certain light wavelengths can promote algea. As far as I know, algea have the same kinds of chlorophyll as plants, and so use the same parts of the light spectrum. Maybe I am missing something there?


Nearest I can fathom is blue is very photosynthetically reactive and algae are faster competers * IF* higher plants are limited by something else i.e CO2..........ect.
As to any difference w/ red???? Not sure there is any data there . 
Most LED's have a blue PAR component re: of color temp.. but not so much red..And warmer LEDs just have less "blue" actinic/Royal blue having the most PAR blue..

I did read somewhere that higher plants are faster at response, and algae is slow to react to changes in light so creating "light breaks" also slows algae.. or allows plants to draw resources faster thus limiting algae growth..

food for thought:


> Although, much less is known about the effect of spectral quality on algal growth, our lighting system based of light emission in the PAR spectrum has proven extremely effective.


http://algaegrowlab.com/index.php/products/lights

Besides corals are symbiotic organisms using algae.. act. blue grows coral...therefore act. is "good" for algae... 

then again , according to "reefers"..


> Because we do not use orange, yellow, or green LEDs in our systems, the spectrum that nuisance algae flourish at is virtually eliminated.


http://www.saltcorner.com/Articles/Showarticle.php?articleID=161

Reefers apparently don't want the color light that fw wants (for aesthetics) because it causes "junk algae" growth...... funny.......

now there could be some chl. A/B type differences between groups, or plant species for that matter (or growth hormones ect.).. but that is a bit more complicated..

for no real reason........
http://plankt.oxfordjournals.org/content/23/12/1373.full


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## Flear (Jul 10, 2013)

when looking up information about lights and spectrums myself, ... 

not a definitive answer, just personal uneducated opinion, LED is the same watt cost per light for plants.

i settled on actinic 460nm mixed with 6500K, ... i haven't looked into the 5500K bulb spectrum. the 6500K spectrum is good for growing, not the best for flowering, my guess is the 5500K might have better reds

adding the actinic will strenthen the deep blues & UV the plants want without reaching into the deep UVC spectrum much.

on a 4-light setup, i would mix 1:3 (actinic460: 6500K)
2 lights turn in 50/50 because there is only 2 bulbs, or go all 6500K

as this is all guesswork on my part, i don't have more to base it on.

---

also found a page that mentioned even coral benefit significantly from 6500K bulbs, making the actinic 6500 mix almost universal

the 10,000K they like to sell for coral has limited reds which is likewise going to be limiting for coral with it's photosynthetic algae requirements. sometimes replicating nature isn't the best we can do.our tanks aren't under 10-30feet of water so we have the option of doing better than nature while still satisfying everything in our tanks without any loss.


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## Cthulhu (Dec 18, 2012)

When choosing the LEDs for my DIY setup, I decided I didn't need any actinic because the 6500K already have lots of blue at the same wavelength. I still haven't ordered yet, but it will most certainly be this :

== Group 1 ==
8x Cool White

== Group 2 ==
5x Warm White
3x cyan

== Group 3 ==
4x Deep Red

Each group on a dimmable driver, so I can adjust the balance as I want. The reds will be dimmed lower than the rest or else it would probably be too much.


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## Italionstallion888 (Jun 29, 2013)

I was running two actinic light on my 55 gallon tank. I kept having terribad algae issues. I took out the actinic lights and only run 2 6700k CF's and my algae problem has pretty much gone away by now. I didn't change anything besides the lights.


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## jeffkrol (Jun 5, 2013)

Cthulhu said:


> When choosing the LEDs for my DIY setup, I decided I didn't need any actinic because the 6500K already have lots of blue at the same wavelength. I still haven't ordered yet, but it will most certainly be this :
> 
> Each group on a dimmable driver, so I can adjust the balance as I want. The reds will be dimmed lower than the rest or else it would probably be too much.


May want to consider pulsing the red channel.. AFAIKT red is more utilized than blue.. horticulturally it is like a 1:4,5,6 mix of b to red. IF you want to go fancy I'd suggest running red full and blue dimmish while your not "looking" then re balance for aesthetics.. That is what I'm "eventually" going to do w/ my 3 channel design.. 
for this I burn the red while I'm at work then cut it down for my enjoyment.. working OK for now (no CO2 additions but some Flourish Excel..)
Picture is w/ 3=30w blue/white and 15=15w warm white











what the fish see while I work...........


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## GEENE (Jan 27, 2014)

I don't know if it only applies to non submerged plants but red is helpful more on the flowering part of a plant, just something I read, whats everyone think


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## jeffkrol (Jun 5, 2013)

GEENE said:


> I don't know if it only applies to non submerged plants but red is helpful more on the flowering part of a plant, just something I read, whats everyone think





> Important Definitions as it applies PAR in plants and zooanthellic algae: See the graph to the left as it corresponds to each of these definitions.
> 
> *A: Phototropic response; having a tendency to move in response to light. Basically this is the Chlorophyll containing plant or algae "moving" to respond to a positive light source to begin the process of photosynthesis (initial growth of plants, zooxanthellae, etc.).
> 
> ...











http://www.reefcentral.com/forums/showthread.php?t=1918382


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## staypuft (Aug 31, 2013)

just a comment, I run a rayII on my tank and a zoomed reef sun t8 for ascetics because it brings out a lot of color and makes the tank look brighter. I think it helps growth but I'M not 100% sure.


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