Blue leds for vegetative growth? - The Planted Tank Forum
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post #1 of 23 (permalink) Old 12-29-2012, 05:10 PM Thread Starter
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Blue leds for vegetative growth?

I read on some places that strong blue light is beneficial to vegetative, leaf producing growth in plants. I know having a reef blue tank probably look horrible but whats wrong with using an actinic or 20 k t5 for awhile the. Switching it out for a 6500 k bulb when the tank is grown out? Why dont we do it for dsm's which dont have the problem of co2 limitation? Needless to say ive already started a dsm using blue leds ao lets see where it goes.
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post #2 of 23 (permalink) Old 12-31-2012, 06:14 AM Thread Starter
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No one's had experience using blue light?
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post #3 of 23 (permalink) Old 12-31-2012, 07:03 AM
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I think acitydweller is trying something like this.
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post #4 of 23 (permalink) Old 12-31-2012, 09:06 AM
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I've run blue lamps for the past four days consecutively and have seen the Asian anubias sprout three leaf nodes on each stem where it previously would have taken approximately a week to grow one leaf node. I have shifted now to running red only light to see it's effects. My tests are on a shrimp tank with only the Asian anubias, crypts and hm both floating and carpeting with no ferts or co2 atm.

Just adding a photo of my test setup:

The results are remarkable.

Peacock moss has grown new buds in a matter of days, crypts have stopped melting and new growth seen in the past three weeks. unfortunately my timer has gone on the fritz so my lighting schedule revolves around my work schedule which is fairly erratic so the test is on haitus for now.

"I am Groot", the faithful protector

Last edited by acitydweller; 01-07-2013 at 06:44 PM. Reason: FO TO YO
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post #5 of 23 (permalink) Old 12-31-2012, 11:38 AM
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excessive blue light often makes plants bloom unnaturally often. it keeps my vals in constant bloom with runners shooting out like crazy.

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post #6 of 23 (permalink) Old 12-31-2012, 02:50 PM Thread Starter
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Interestingly enough my H. sibprothoides bloomed under my bloom LEDs after only 4 days of emersed growth after being transplated from submersed growth. IDK if that's just coincidence though. So I didn't pay much attention to it.
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post #7 of 23 (permalink) Old 12-31-2012, 04:50 PM
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I'm curious to hear more cases of blue lights and aquatic plant growth. In the reefing world, the general feel on the blue light was it didn't really provide anything useful to the coral, and I'm talking the actinic blue bulbs, not 20k which has the reds, yellows, greens ect. It was used to enhance colors and provide moon lighting in some cases. In theory blue light should be great for photosynthesis so I don't see why not. I could see throwing some blue LED's on a tank if for nothing else to pop the colors.
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post #8 of 23 (permalink) Old 01-01-2013, 01:37 AM
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I run a couple of 470nm and 660nm LEDs. Compared to my tank with just 6700k CF bulbs, I've gotten the same amount of growth out of my dwarf baby tears in 3 weeks that took 3 months in the tank with the CFs.
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post #9 of 23 (permalink) Old 01-06-2013, 06:13 PM Thread Starter
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after about 9 days of growing.

it started from about 5 leaves of hydrocotyl.

Running 6w 10k and 10w blue
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post #10 of 23 (permalink) Old 01-06-2013, 06:50 PM
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I have to correct myself red has more to do with blooming, blue has more to do with growth if i remember right

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post #11 of 23 (permalink) Old 01-06-2013, 11:11 PM
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Its no secret that blue light is used for vegetative growth in alot of different applications. I really dont understand why there hasnt been more discussion and experimentation with blue lighting in planted tanks.

I consider myself pretty well versed in aquarium lighting, and I have seen almost no solid information about blue lights for planted tank growth. Marineland has blue diodes in their plant light led, but almost all companys refer to bulbs that appear pink as "plant grow" bulbs. When I get my new light fixture from catalina (hopefully by the end of next week) I plan on running atleast 1 blue t5 in the mix.

I hope some more people with reallife experience using blue bulbs chime in!
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post #12 of 23 (permalink) Old 01-07-2013, 03:12 AM
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Best wavelengths for photosynthesis:

Chlorophyll A: 435 - 665 nm
Chlorophyll B: 490 - 650 nm

I'm interested to hear as well.

As an experiment, Ive ordered a KZ Fiji Purple for its red spectrum. Its the only bulb I can find which would satisfy a plants chlorophyll A spectral needs in red @ at 650nm. The blue end of the spectrum seems to me much easier to find and satisfy.

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post #13 of 23 (permalink) Old 01-07-2013, 05:21 AM
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Besides some experiments with the blue part of the spectrum we also need some more understanding of how the light intensity works versus the spectrum. I say that because recently I stumbled on a bit of a strange situation:

I'm running a 30W 10,000K LED together with one 24W 6000K Giesemann Midday T5HO bulb. This combination caused the plants to pearl within minutes after setting up both lights for the very first time. This is the LED:

Now check this out:

- LED+T5HO are on: Pearling = 100%
- Only T5HO: Pearling = 0
- Only LED: Pearling = 75%

Why isn't the pearling staying at 25% with the T5HO only? Looks like there is a beneficial interaction between the "strong arm" light and the "good spectrum" light. Or maybe the blue-er light is indeed better for the photosynthesis. Unfortunatelly I do not know the wavelengths of the 30W LED and I am comparing a single element LED with a 24" long fluoresent bulb. Of course the LED will hit the plants with more light in one spot. Anyway - the LED has got to have a lot of blue because without the 6000K bulb the colors in the tank are very washed and the backs of the neon tetras glow very strong blue.

Today I added a third light to the above combo - a 14W red and blue light (has 272 leds: 204 Red (615-655nm) + 68 Blue (455-485nm)):

I wanted to see if that weird (mainly red) color grow light will do something interesting to the aquatic plants. I can say for sure that it did speed up the photosynthesis - I turned the grow light on and off and counted the release rate of a single Oxygen bubble that came out of one of the plants. With the grow light the bubble came out every 3 seconds. As soon as I turned the light off it slowed down to 5 and eventually 7 seconds. I repeated that a few times and there was a definite connection. Very scientific, I know, but it did show that the grow light with its mostly red LEDs sped up the photosynthesis. And from what I see now the range 615-655 nm that my grow light provides may not be the best (some graphs show Chlorophyl A absorbing best at about 680 nm):

Also, another observation - after 4 hours of exposure to that light I saw a 1/2 inch flower stem with buds forming showing up on the sword that was right under the light. I don't know if the grow light had something to do with that but the stem was not there when I installed the grow light.

I should have experimented with the grow light only by turning off the other 2 lights. I will do that tomorrow. That's a light that gets pretty close to both areas of interest for the photosynthesis. I'm interested to see if there will be pearling despite the low intensity. There shouldn't be any - 14 Watts going through 18 inches of water should not work. But read the weird observation about the LED + T5HO pearling above. I experiment again tomorrow.

Last edited by niko; 01-07-2013 at 05:34 AM. Reason: added a picture
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post #14 of 23 (permalink) Old 01-07-2013, 06:28 AM
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funny... i have been squeezing blue lights into my tanks for years. lately, i am using actinics because they cause the plants to produce more red pigments. LEDs will not cause this, unless they produce UV. i do have some blue grow panel LEDs that i have tested and noticed some incredible growth rates, but the plants didnt show the deep reds that i like so i switched back to actinics.

i usually meet with ridicule when i mention this though, so i normally just keep it to myself...
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post #15 of 23 (permalink) Old 01-07-2013, 07:14 AM
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Its funny you say that auban, because I was just thinking about what would happen if I used an actinic bulb along with one of the pink plant bulbs.
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