Colored Lighting And Plant Growth

Hello all, I have been trying to better understand aquarium plant growth and the little details and tricks to achieve different goals. I understand that at least in terrestrial plants, red and blue lighting is most effective for photosynthesis and I assume the same to be the case in aquatic plants. But my question is, do we see different growth patterns or changes under certain color lighting? Like for example, would higher quantities of red lighting make a plant grow more bushier or have outward growth while blue lighting focused more on height? Those are just examples of what I am trying to ask, but I can't find anywhere that says something on this. I thought I would ask this community and try en experiment as well anyways.

 

HI Turtledrew15,

The short answer is "no"; the spectrum (aka color) of light does not effect plant growth. Probably the most renowned photobiologist in the United States is Dr. Bruce Bugbee of Utah State University. He has proven that plants will grow equally with any light spectrum within the photosynthetic usable radiation (PUR) range as long as the light intensity at each spectrum is equal. What does determine plant growth is Photosynthetic Photon Flux Density or “PPFD” (a term we in the hobby typically think of as Photosynthetically Active Radiation - PAR) which is how we measure light intensity in the amount of photons which strike a given area typically measured in micromoles per square meter per second.

So don't worry about 'spectrum' such as 6700K or 10000K or 5500K, instead concentrate on maximizing PAR (light intensity) and chose a spectrum that is pleasing to your taste and makes the fish and plants look good to you.

 

Very helpful response thank you so much. Was Dr. Bugbee's conclusion for both aquatic and regular plants? Because this video shows different growth for 4 species of plants under the same intensity of red, blue, and white light and I'm wanting to know what the explanation is if what you say is proven.

 

HI Turtledrew15

Dr Bugbee is a preeminent researcher and author/co-author of nearly 200 peer-reviewed journal articles. Here is one of his 200 papers dealing with optimum light spectrum. I think a couple of points are relevant here; 1) not all plants are the same, they all evolved in different environments with different light intensities and spectrums (due to shading, sun angle, etc) so what may be good for one plant species may be detrimental to another. 2) although photosynthesis is optimized in a couple of bandwidths plants utilize light from all portions of the PAR range (and possibly beyond). In many species leaf shapes and sizes can be influenced by light spectrum but those light spectrum's (as perceived by our eyes) make the plant and fish colors look "unnatural" and decrease our enjoyment of viewing our fish or plants. Personally I keep fish in planted tanks because I enjoy seeing fish in a more 'natural environment'. And although I enjoy growing plants in my tanks my primary concern is the health of the fish species, the plants and their needs are secondary.

Along with my tanks I grow a several of the more difficult to source species 'emersed' for future aquascaping needs; different species definitely prefer different conditions.

 

HI Turtledrew15

Dr Bugbee is a preeminent researcher and author/co-author of nearly 200 peer-reviewed journal articles. Here is one of his 200 papers dealing with optimum light spectrum. I think a couple of points are relevant here; 1) not all plants are the same, they all evolved in different environments with different light intensities and spectrums (due to shading, sun angle, etc) so what may be good for one plant species may be detrimental to another. 2) although photosynthesis is optimized in a couple of bandwidths plants utilize light from all portions of the PAR range (and possibly beyond). In many species leaf shapes and sizes can be influenced by light spectrum but those light spectrum's (as perceived by our eyes) make the plant and fish colors look "unnatural" and decrease our enjoyment of viewing our fish or plants. Personally I keep fish in planted tanks because I enjoy seeing fish in a more 'natural environment'. And although I enjoy growing plants in my tanks my primary concern is the health of the fish species, the plants and their needs are secondary.

Along with my tanks I grow a several of the more difficult to source species 'emersed' for future aquascaping needs; different species definitely prefer different conditions.
View attachment 471401

Thank you for linking the article and providing a detailed response! I'll just go with full spectrum lighting that appeals to me and has great PAR

 

HI Turtledrew15

Dr Bugbee is a preeminent researcher and author/co-author of nearly 200 peer-reviewed journal articles. Here is one of his 200 papers dealing with optimum light spectrum. I think a couple of points are relevant here; 1) not all plants are the same, they all evolved in different environments with different light intensities and spectrums (due to shading, sun angle, etc) so what may be good for one plant species may be detrimental to another. 2) although photosynthesis is optimized in a couple of bandwidths plants utilize light from all portions of the PAR range (and possibly beyond). In many species leaf shapes and sizes can be influenced by light spectrum but those light spectrum's (as perceived by our eyes) make the plant and fish colors look "unnatural" and decrease our enjoyment of viewing our fish or plants. Personally I keep fish in planted tanks because I enjoy seeing fish in a more 'natural environment'. And although I enjoy growing plants in my tanks my primary concern is the health of the fish species, the plants and their needs are secondary.

Along with my tanks I grow a several of the more difficult to source species 'emersed' for future aquascaping needs; different species definitely prefer different conditions.
View attachment 471401

Could you link another article of his? The one provided was just s and some of them seemed to example that different lights gave different yields

 

HI Turtledrew15,

Possibly I misunderstood your question, 'growth', 'yield', 'growth habit' (i.e. bushiness) are all different. I guess it depends upon what we are trying to accomplish with the plants in our tanks. I think my favorite light fixture at this time is the Fluval Plant Spectrum (aka 3.0). Why? Because each led color is adjustable independently and is light intensity (PAR) programmable via bluetooth and a free app for your phone, it has very good PAR output even in deeper (20"+) tanks, it has a three (3) year warranty, and it is made by Fluval / Hagen an internationally recognized brand with a toll-free number for service. I currently am using the Fluval (2.0) on two of my tanks and after 2+ years I can strongly recommend the brand; here is a comparison of the three most popular fixtures that I did 2 years ago.

My experience has been that plant 'bushiness' or stem 'lankiness' (elongated internodal spacing) is much more an attribute of light intensity (PAR) than spectrum. Many of Dr. Bugbee's papers are available online if you choose to Google them.

 

HI Turtledrew15,

The short answer is "no"; the spectrum (aka color) of light does not effect plant growth. Probably the most renowned photobiologist in the United States is Dr. Bruce Bugbee of Utah State University. He has proven that plants will grow equally with any light spectrum within the photosynthetic usable radiation (PUR) range as long as the light intensity at each spectrum is equal. What does determine plant growth is Photosynthetic Photon Flux Density or “PPFD” (a term we in the hobby typically think of as Photosynthetically Active Radiation - PAR) which is how we measure light intensity in the amount of photons which strike a given area typically measured in micromoles per square meter per second.

So don't worry about 'spectrum' such as 6700K or 10000K or 5500K, instead concentrate on maximizing PAR (light intensity) and chose a spectrum that is pleasing to your taste and makes the fish and plants look good to you.

View attachment 471269

I think it's important to note that the PAR rating while important to plant keeping aquarists, those numbers can be misleading. If the photons reaching X depth in the water column are NOT in the photosynthetic range then they are pretty useless to plants. Lights that provide a greater amount/intensity in that important range will be better for the planted tank, hence the inclusion of individual RBG LED's in more "high tech" planted tank light fixtures. The photosynthetic range is not the full spectrum of "white" light.

 

HI Pescado_Verde

When Cara Wade from 'Build My LED" (when BML was still doing aquarium fixtures) visited our club in Seattle a couple of years ago and did two talks I learned a lot about lighting. For example, I was not aware that 'White LEDs' are actually 'blue LEDs' with a phosphor coated lens which causes the light to look white to our eyes.

 

HI Pescado_Verde

When Cara Wade from 'Build My LED" (when BML was still doing aquarium fixtures) visited our club in Seattle a couple of years ago and did two talks I learned a lot about lighting. For example, I was not aware that 'White LEDs' are actually 'blue LEDs' with a phosphor coated lens which causes the light to look white to our eyes.

Vapor lamps have been using similar for years. Otherwise they give off a greenish cast. Not sure what the point is but yes, manufacturers use various techniques to produce the lights we use.