# BLue and Red ONLY aquarium light



## walzon1

Recently built a DIY LED and it's kind of overkill for my Low tech aquarium, currently is running 36 watts of 7500k and 24 watts RGB on a 40 gallon tall. In the my time to limit the GSA outbreak I am having I have been running only the Blue and Red of the RGB, my question is since plants mostly use the blue and red spectrum for photosynthesis how long can I get away running my "Purple" lights until the plants will be affected, or is the white light unnecessary and will the plants grow fine without it.


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## Rusty

I would think you could get away with it for as long as you want. A lot of hydroponics and other terrestrial plant growers use purple lights. However, it may not be pleasing to the eye unless you have all glofish or something  Of course, you can do your own experiments and let us know in a few months how your plants are doing


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## Yo-han

I expect the same as rusty. Plants will do perfect, but you won't like it


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## TropTrea

I will agree only to a limited extent that this can work for you. Having had worked with LED lighting on reef tanks I know that the colored LED lights have a very narrow spectrum. With a combination of different blues and red LED's it is possible to cover a majority of the photosynthetic spectrum but with just two colors you would not be covering the entire spectrum. 

An example on the blue end of the spectrum,
Royal Blues peak at around 450 to 455 nm with 90% of output between 445 and 460 nm.
True Blue peak between 460 and 470 nm with 90% of there spectrum between 455 and 475 nm. 
Cyan LED's peak between 500nm and 510 nm with 90% of there output between 490 and 520 nm.

Now the entire photosynthesis range in the blue end of the spectrum is between 410 and 490 nm. 

You have the same issue with the red wave lengths of LED's with the photosynthetic range being between 570 and 680 nm. 


Red-Orange LEDs peak between 610 and 620nm with 90% of there output between 600 and 630 nm.
Red LEDs peak between 620 and 630 nm with 90% of there output between 610 and 640 nm.
Deep Red LED's peak between 655 and 665 nm with 90% of there output between 645 and 680 nm. 

Where the Blue and Red LED's do help a lot is to boast the lighting from the various "white" LED's when your balance from the "whites" is off for your particular purpose. 

Not knowing the specific brand names and color temperatures of your LED's I cannot give any accurate advice other than I would rely more on the full spectrum LED'
s. With the full spectrum ed LED's being 7,500K I would suspect you need a little more of a boast in the red range compared to the blue range however. 

As far as your wattage is concerned On some of my reef tanks I have found that at roughly 2 watts per gallon I can get over 120 PAR at the substrate and in some cases even 150 PAR. This is beyond what is needed for even the most light demanded plants in the fresh water world. Right now I have 3 10 gallon tanks for the breeding on live bearer fish and only 2 Watts of Neutral White (4,100K) LED's on each. Very month I need to thin out the myriophillium in those tanks. 

Since your lighting is DIY perhaps changing to a dimmable controller on your 7,500K LED's would become a much simpler and safer solution for you?


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## walzon1

TropTrea said:


> I will agree only to a limited extent that this can work for you. Having had worked with LED lighting on reef tanks I know that the colored LED lights have a very narrow spectrum. With a combination of different blues and red LED's it is possible to cover a majority of the photosynthetic spectrum but with just two colors you would not be covering the entire spectrum.
> 
> An example on the blue end of the spectrum,
> Royal Blues peak at around 450 to 455 nm with 90% of output between 445 and 460 nm.
> True Blue peak between 460 and 470 nm with 90% of there spectrum between 455 and 475 nm.
> Cyan LED's peak between 500nm and 510 nm with 90% of there output between 490 and 520 nm.
> 
> Now the entire photosynthesis range in the blue end of the spectrum is between 410 and 490 nm.
> 
> You have the same issue with the red wave lengths of LED's with the photosynthetic range being between 570 and 680 nm.
> 
> Red-Orange LEDs peak between 610 and 620nm with 90% of there output between 600 and 630 nm.
> Red LEDs peak between 620 and 630 nm with 90% of there output between 610 and 640 nm.
> Deep Red LED's peak between 655 and 665 nm with 90% of there output between 645 and 680 nm.
> 
> Where the Blue and Red LED's do help a lot is to boast the lighting from the various "white" LED's when your balance from the "whites" is off for your particular purpose.
> 
> Not knowing the specific brand names and color temperatures of your LED's I cannot give any accurate advice other than I would rely more on the full spectrum LED'
> s. With the full spectrum ed LED's being 7,500K I would suspect you need a little more of a boast in the red range compared to the blue range however.
> 
> As far as your wattage is concerned On some of my reef tanks I have found that at roughly 2 watts per gallon I can get over 120 PAR at the substrate and in some cases even 150 PAR. This is beyond what is needed for even the most light demanded plants in the fresh water world. Right now I have 3 10 gallon tanks for the breeding on live bearer fish and only 2 Watts of Neutral White (4,100K) LED's on each. Very month I need to thin out the myriophillium in those tanks.
> 
> Since your lighting is DIY perhaps changing to a dimmable controller on your 7,500K LED's would become a much simpler and safer solution for you?


Thanks, I was just curious cause even though I have seen the grow lights that are Purple those are made specifically for growing plants as I am using LED strips, which are basically cosmetic in function it's true that I have no idea what spectrum they are . Might cause problems for prolonged use. Today I cut the whites in half to 18 watts since they are strip lights it's basically trial and error right now.

I;m assuming the 2 watts over the 10g are 1 watt LED's cause It definitely wouldn't be enough light using the strips I have. Currently running 8.5 watts White and 3.3 watts REd on a 10g and it seems like it might be too much. I'm finding a lot of it comes down to the concentration of the LED strips per area. I had around the same amount of wattage over 20" length of the tank and it wasn't enough light, after a couple different tries I now have pretty much the same amount of watts on a 16" sheet and so far the plants are reacting like it's too much light. I'm hoping it's just adjusment period.


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## TropTrea

walzon1 said:


> I;m assuming the 2 watts over the 10g are 1 watt LED's cause It definitely wouldn't be enough light using the strips I have.


Actualy it is one 5 Watts LED that is designed to run at 1,500ma for the full 5 Watts but I'm running it at 700ma which reduces it to 2 Watts. I have 6 ten gallon tanks lined up one next to each other with the short side out for viewing. This was an experiment set up for me initialy aiming for viewing of the fish rather than growing plants. However I added myrophillia to these tanks that is growing like crazy. In the experiment I have some with a neutral white (4,200K LED that are turning out great and others with a Cool White 6,200K LED that have an algea issue but the plants are still growing.



walzon1 said:


> Currently running 8.5 watts White and 3.3 watts REd on a 10g and it seems like it might be too much. I'm finding a lot of it comes down to the concentration of the LED strips per area. I had around the same amount of wattage over 20" length of the tank and it wasn't enough light, after a couple different tries I now have pretty much the same amount of watts on a 16" sheet and so far the plants are reacting like it's too much light. I'm hoping it's just adjusment period.


With LED's the varieties of them out there are vast. Some are extremely efficient like the CREE XP and XM series. Running some of them at low watts actually yields well over 140 lums per watt consumed. Only 5 years ago it was impossible to exceed 70 lums per watt and some of the manufacturers are still producing some extremely inefficient LED's.

Another big issue with LED's is the use of lens and how they spread out the light without lenses. My first lighting fixture I built I had used 45 degree lenses as I figured it would spread the light equally on the substrate that was 20" away from the lights. The beaming effect had me order 60 degree lenses a week later and again 90 degree lenses a week after I switched to the 60's. Today I no longer use any lenses unless there is more than a 27" difference between the substrate and the height of the LED's.


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## micheljq

You would cover the spectrum better with red and blue leds. But it will be ugly. It is better to put mostly white leds, like cool white and then add some blue and red leds mixed with the cool whites.

Do a research on internet for diy led fixtures.

Michel.


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## TropTrea

micheljq said:


> You would cover the spectrum better with red and blue leds. But it will be ugly. It is better to put mostly white leds, like cool white and then add some blue and red leds mixed with the cool whites.
> 
> Do a research on internet for diy led fixtures.
> 
> Michel.


Yes it will work on a larger aquarium. With a smaller aquarium the problem is that both red and blue LED's put out a lot of light in a very narrow spectrum. Therefore you end up with a ration like 1 blue and 1 red for each 3 or 4 cool whites. Using neutral whites which have a stronger red end to the spectrum will eliminate the need for the extra red LED's. However you will still want a slight boast in the blue end which is weaker than the cool whites. But you can get away with a ration of 1 blue to 2 neutral whites.

Now I perfer simply mixing neutral and cool whites but others have also had success with
neutral or even warm whites with blue LED's or
cool whites with additional red LED's.

But caution on the red LED's there are different reds from 620 nm up to deep red at 680 nm. If you want to cover the entire red photosynthesis spectrum on the red end with red LED's you would be using 3 different types of red.

The other issue with using multiple colored LED's is if you do not mount them real close to each other you get color banding or the disco effect. When you mount the close together then you need to ren them at lower currents or invest more in cooling them.


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## kyle2088

I have been using the red and blue strips lights 5050 over 2 of my 75 gallon tanks for 3-4 months now.

Originally I was using 6 x t5ho 48length tubes mix giesmann midday and aquaflora and reduced it to only 4 bulbs with the addition of 2 x 100cm strips of red and blue mix 5:1 and 2 strips of pure reds. 4 strips = 58 watts (the 2 t5ho i stopped using were using 108W) Even at powered on max there is no...very little visible difference at the bottom of the tank with the t5ho's on they overpower the light. Even with only 2 t5ho bulbs powered on and the 4 strips at 14.5 watt per strip there is little to no difference to the human eye that is until the plants get about 10cm from the surface and there is more intense colours in red plants the same holds true when all 4 t6ho are powered on there is noticeable difference in reds near the surface..

That being said growth is still similar maybe even a bit less as compared to 6 bulbs (which is fine prior to this I had to proon very frequently especially stem plants becoming a hassell) and I have reduced 40 watts from being used. No crazy algae outbreaks and I havnt been regular dosing ferts as much (maybe once a wek if I remember) and only use tabs with occassional liquid ferts.I used a standard hydroponic 6 x 4ft light fixture and only use 4 bulbs with the other 2 spare fixtures hiding the led strips so it all fits inside the fixture.

I am currently going to try this method with the 5630 leds that use about the same amount of electricty but give off more par/lumens however the red wavelenghs are different 640nm as oppose to 660 nm in 5050. Also they dont have the mixed red blue strips like they have in the 5050's.

So just an alternative to the red/blue only you can try a mixture Possibly obtain the best of both worlds. I have seen the red/blue only fixtures in person and it is very difficult to look at let alone get used too.


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## TropTrea

Working with LEDs and reef tanks I found that most LED's were lacking in the 480 to 520 nm range with a dead spot especially at 500nm. Supplementing the LED's with HO T-5's ATI's Blue plus bulbs fixed this problem real easy in combination with the LED's. 

The problem with fresh water though is the Blue Plus Bulbs are extremely strong in the blue spectrum and will cause algae to go wild. For fresh water plants I cannot see where the lack of light in the 500nm range would effect anything. 

I have found that even running all cool white LED's supposedly 6,000K creates a very heavy blue balance even though they are producing some red and green light. I prefer mixing them with a more balanced neutral white, supposedly 4,500K, which give off less blue and more red than cool whites. 

As far as the appearance of red plants this is partly do to the reflective quality of the plant and the balance of the light they are receiving. They will only reflect red light so the more red you give them the brighter they will be. If you give them less red light they will start looking darker even a dark brown color. Singularly the less green light delivered the less the light the green plants will reflect causing the darker green foliage look.

But remember as well if they reflect the light back they not using that light for photosynthesis. The light they use is actually the light they absorb rather than reflect. So the level of red light for red plants is not as important for growth as it is for plants that are green or even blue=green.


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