Light colour & algae

[oreo57]

Hi all,

That one for me, near enough is near enough.

cheers Darrel

I did not say you need full spectrum. I only said it seems to be preferable compared to only blue and red. RGB is by no means full spectrum and still grows very nice plants. For me any ordinary white LED is full spectrum enough (although they usually have very little violets, deep blues, cyan and reds, so technically it might not really be full spectrum)

for the past 6 years I use self made led lamps with one or more types/colors of good quality leds. I experimented with adding 660nm reds, it should help aquarium plants to grow more compact, and maybe it does, but under the total amount of light plants will grow compact anyway, so I don't think it is really worth the trouble. (it does give a nice sunrise though). I used 730nm far red to see if the emerson effect would speed up plant growth, I do think it had some effect. but the tank was quite dimly lit, In terms of energy efficiency maybe it was doing quite well, but unless you like a cheap brothel look, the esthetics were awful.

And aquarium lightning is not about maximum yield with a high energy efficiency, it is about esthetics. Since aquatic plants are not light demanding at all compared to most other plants and crops, just get a light that makes your tank look goed and your plants will probably be fine. I enjoy all the discussions about spectra, and love reading about it, trying things for myself. Good fun, but practically a complete waste of time.

One needs to consider the upside down world of water.
High red content signals high light.
Low or no red signals low light.
The opposite of the terrestrial environment.

Also "we" aren't shooting for max dry weight or tweaking aromatics/vitamins ect.

Then there is the almost always limiting factor of CO2 compared to terrestrials.

The confusing use of " full spectrum" is just annoying.

Connection Problem

 

[jaypeecee]

it is indeed a widespread misconception that plants will grow better if provided with light in the wavelengths they can absorb best. this is not true, it is only more energy efficient (to some extend)

Hi @akwarium

It was your statement above that caught my attention. If, as you say, "it is only more energy efficient", does this not result in improved growth? And, by this, I mean in terms of height, width and sturdier growth? Surely, more efficient light/energy transfer from the light source to the receiving plant has got to be a positive thing - no? One observation I've made is that all natural processes have evolved to optimize the usage of energy. Why would photosynthesis be any different? Nature has an inherent intelligence that blows my mind.

JPC

 

[jaypeecee]

Yes, oxygen release correlates very closely with CO2 incorporation. This is because for every molecule of CO2 that enters photosynthesis a molecule of oxygen (O2) is liberated. Plants are made of a carbon skeleton, and their growth is a measure of the net difference between CO2 absorbed and oxygen liberated.

Thanks, Darrel (@dw1305)

Simple answer, succinctly expressed.

Bravo!

JPC

 

[jaypeecee]

Is there any colour light that is less prone to helping algae? Without working things out scientifically, I'm wondering about purely green light (as I think that what's reflected from green leaves... right?)

Hi @idris

It doesn't make sense to me to use aquarium lighting with spectrum peaks at around 565nm and/or 620nm. The first of these corresponds to peak sensitivity of red algae species (e.g. BBA). The second of these corresponds to peak sensitivity of Cyanobacteria (aka BGA). This is because each of these species contains accessory pigments - phycoerythrin and phycocyanin, respectively. In terms of lighting colour, these correspond to green/yellow and red, respectively.

As for the green part of the spectrum, a lot of green light is reflected from plants and that's why they appear green to us. But, green light penetrates deeper into the leaf.

JPC

 

[oreo57]

Tweaking spectrum to control algae (any type) would be THE LAST consideration.
Certainly with green algae.
A MINOR argument w/ red algea may have "some" History though has shown healthy growth and tank cleanliness are very effective.
Fun paper..

PHOTOSYNTHETIC ACTION SPECTRA OF MARINE ALGAE - PMC

A polarographic oxygen determination, with tissue in direct contact with a stationary platinum electrode, has been used to measure the photosynthetic response of marine algae. These were exposed to monochromatic light, of equal energy, at some 35 ...

www.ncbi.nlm.nih.gov

One thing to note is chlorophyll is present though apparently err turned off. So much for natures " efficiency".

Pick a light that pleases you.

 

[MichaelJ]

It doesn't make sense to me to use aquarium lighting with spectrum peaks at around 565nm and/or 620nm

Hi @jaypeecee I believe a lot of aquarium light corresponds to daylight (from slightly cooler to slightly warmer) and contains a lot of energy in the 550-650nm range - while it may not technically peak around there, it's still a pretty significant amount of the total energy. If you were to dial down that particular part of the spectrum your light and your tank wouldn't look very natural - so I don't really see that as a viable option. I think it's safe to say that any meaningful light, regardless of the spectral constituent, will promote algae if the tank is out of balance with regards to overall light intensity, , CO2, nutrients, waste etc. In my own tanks my light probably correspond to something slightly warmer than daylight or ~5500K (a huge lump in the 550-650nm range), and I don't have any algae to speak of.

Cheers,
Michael

 

[akwarium]

Hi @akwarium

It was your statement above that caught my attention. If, as you say, "it is only more energy efficient", does this not result in improved growth? And, by this, I mean in terms of height, width and sturdier growth? Surely, more efficient light/energy transfer from the light source to the receiving plant has got to be a positive thing - no? One observation I've made is that all natural processes have evolved to optimize the usage of energy. Why would photosynthesis be any different? Nature has an inherent intelligence that blows my mind.

JPC

I think you gave the answer yourself. to be efficient in harvesting as much energy as possible from the light that hits them, plants(and algae) also need to absorb the light that is the hardest to adsorb. Because the intelligence of nature(evolution), they have found ways to do so. So like said by me and others before, all wavelengths ,even the green, are absorbed pretty well, and more import green has his own function in reaching deeper into the plant tissue. Plants have been growing for 500 million years under the sun. Trying to use a different spectrum is trying to outsmart nature. As you point out yourself the room for that is very limited.

Any plant depending its size, chlorofyll content, nutrient availability, carbon availability and all other kinds of physical and environmental factors, can produce a X amount of sugars per day. Therefore it needs X amount of photons(DLI). as long as those are provided the plant will grow at its best (given the circumstances). Red and blue leds are at least in theory more efficient in producing light then white leds, and red and blue light are also absorbed a bit better. So you probably need a bit less leds/power to provide the X amount of photons: you save some energy.
Complicating factor is that spectrum is also one of those environmental factors that determine how much photosynthesis there can/will be.

 

[dw1305]

Hi all,

Plants have been growing for 500 million years under the sun. Trying to use a different spectrum is trying to outsmart nature. As you point out yourself the room for that is very limited.

That is the one for me, only one sun and also <"all photosynthetic organisms contain chlorophyll a">.

That chlorophyll a was originally in the <"free living cyanobacteria"> that are now in <"every eukaryotic photosynthetic plant cell"> as the organelle "a chloroplast".

In the widest sense all photosynthetic organisms belong <"to the same clade">.

.......... Between 1 and 1.5 billion years ago [1, 2], eukaryotic organisms acquired the ability to convert light into chemical energy through endosymbiosis with a Cyanobacterium (e.g., [3, 4, 5]). This event gave rise to “primary” plastids, which are present in green plants, red algae, and glaucophytes (“Plantae” sensu Cavalier-Smith [6]). The widely accepted view that primary plastids arose only once [5] implies two predictions: (1) all plastids form a monophyletic group, as do (2) primary photosynthetic eukaryotes........

In a more restricted sense all "green plants" (<"viridiplantae or chlorobionta">) are a monophyletic clade which have the same photosystems and basic physiology.



Personally I think we are back to <"re-arranging the deck-chairs on the Titanic"> if we take too much time worrying about wavelengths and spectra. All you need is to have a light that provides <"enough PAR for your plants to reach LCP">.

cheers Darrel

 

[jaypeecee]

All you need is to have a light that provides <"enough PAR for your plants to reach LCP">.

Hi @dw1305 & Everyone

There isn't a problem with planted aquariums receiving enough light. LED fixtures have taken care of that.

I'm more concerned about the potential effects of a sub-optimum lighting spectrum, too much PAR and photoperiod duration. In other words, potentially encouraging algae and Cyanobacteria growth. A good few aquarium lighting fixtures emit light at 625nm but this is unlikely to be of much benefit to plants. Not so for Cyanobacteria whose peak sensitivity occurs at this very wavelength. And it does appear that spectrum plays an important part in plant shape. According to Dr Bruce Bugbee of Apogee Instruments, blue light shrinks plants (or words to that effect). Or does this not apply in the aquatic environment?

If I've got all my facts wrong, then could you or anyone else please correct me?

JPC

 

[idris]

All fascinating stuff, and mostly beyond my level of knowledge. I just asked the question as I'd like to extend the illuminated hours so I can watch my tank without promoting algae, and was hoping eg green light might tick enough boxes.

 

[jaypeecee]

All fascinating stuff, and mostly beyond my level of knowledge. I just asked the question as I'd like to extend the illuminated hours so I can watch my tank without promoting algae, and was hoping eg green light might tick enough boxes.

Hi @idris

Green light would be my choice and not too bright. At least your plants will appear the colour that nature intended. That's assuming your plants are green, not red, yellow or some other colour. 😉

JPC

 

[ceg4048]

Personally I think we are back to <"re-arranging the deck-chairs on the Titanic"> if we take too much time worrying about wavelengths and spectra. All you need is to have a light that provides <"enough PAR for your plants to reach LCP">.

Exactly. This is the long and the short of aquarium lighting. What folks fail to understand is that LCP for plants is very low, somewhere between 10-20 micromoles. It's very unlikely that any bulb we use in the typical tank scenario produces energy below LCP at any location in the tank.

All fascinating stuff, and mostly beyond my level of knowledge. I just asked the question as I'd like to extend the illuminated hours so I can watch my tank without promoting algae, and was hoping eg green light might tick enough boxes.

As discussed earlier, use whatever bulb you want as long as you do not exceed the brightness that will trigger algal blooms.
No wavelength or spectrum will save you from algal blooms. Simply avoid using too many bulbs and if you elect to use an LED then make sure it comes with a controller that can vary the intensity. It is intensity that does the damage, not the wavelength.

Cheers,

 

[jaypeecee]

It is intensity that does the damage, not the wavelength.

So, does this mean that Dr Bruce Bugbee's statement 'blue light shrinks plants' does not apply to submerged plants? I realize that this example is not a case of plant damage but it has to be considered as less than ideal. We don't really want blue light (or any other part of the PAR spectrum) interfering with healthy growth. It's worth noting that blue light at 430nm has 50% more energy than red light at 645nm. In this respect, intensity and wavelength are inter-related. Furthermore, we should also take into account that red light is additionally attenuated by water even at just 30cm depth.

JPC

 

[jaypeecee]

I think it's safe to say that any meaningful light, regardless of the spectral constituent, will promote algae if the tank is out of balance with regards to overall light intensity, , CO2, nutrients, waste etc.

Hi @MichaelJ

Yes, I agree. I never meant to imply that lighting is the only factor in giving rise to algae or Cyanobacteria growth. Far from it. As a result of my experiments with Cyano, I can probably point to half a dozen factors that promote growth of the Blue-Green Menace in our tanks.

JPC

 

[erwin123]

So, does this mean that Dr Bruce Bugbee's statement 'blue light shrinks plants' does not apply to submerged plants? I realize that this example is not a case of plant damage but it has to be considered as less than ideal. We don't really want blue light (or any other part of the PAR spectrum) interfering with healthy growth. It's worth noting that blue light at 430nm has 50% more energy than red light at 645nm. In this respect, intensity and wavelength are inter-related. Furthermore, we should also take into account that red light is additionally attenuated by water even at just 30cm depth.

JPC

2hr Aquarist cites the following article which suggests that different considerations apply to submerged plants (i.e. those that have an emersed and submersed form have a preference to be emersed?) : Ethylene-promoted Elongation: an Adaptation to Submergence Stress


I'll let the experts summarise it....🙂

 

[oreo57]

So, does this mean that Dr Bruce Bugbee's statement 'blue light shrinks plants' does not apply to submerged plants? I realize that this example is not a case of plant damage but it has to be considered as less than ideal. We don't really want blue light (or any other part of the PAR spectrum) interfering with healthy growth. It's worth noting that blue light at 430nm has 50% more energy than red light at 645nm. In this respect, intensity and wavelength are inter-related. Furthermore, we should also take into account that red light is additionally attenuated by water even at just 30cm depth.

JPC

Photosynthesis doesn't care about energy states.
Only photons.

and that a minimum of eight photons of light must be absorbed in the process.

Doesn't matter about the " color".
Yea lots of blue light with little red can shrink internode elongation creating err stumpy stem plants but that is just a form not function thing. Not a matter of "health" Takes reef level of blue to do it though.

ADDENDUM: Early in my led light building I experimented with color a bit. Crude and short but the resultst are fairly easy to see.
I ran some large blue centric multichips for a brief period just to se the results..
Chips were "actinic" (royal blue) and high k white (14000?) 10w chips. Since they were cheap not going to swear by wavelengths or anything but the results are easy to see in the below pic.
Transition from wide to very short internodes is obvious. Health was same or arguably better but denser. Color was better but not really visible under that little red light.
Don't believe I ran the "experiment" for more than a few weeks if that.
Young tank so a mess but that's not why I'm posting it. :

 

[ceg4048]

So, does this mean that Dr Bruce Bugbee's statement 'blue light shrinks plants' does not apply to submerged plants? I realize that this example is not a case of plant damage but it has to be considered as less than ideal. We don't really want blue light (or any other part of the PAR spectrum) interfering with healthy growth. It's worth noting that blue light at 430nm has 50% more energy than red light at 645nm. In this respect, intensity and wavelength are inter-related. Furthermore, we should also take into account that red light is additionally attenuated by water even at just 30cm depth.

JPC

Any high intensity light will damage aquatic plants if CO2 and nutrients are lacking. On the contrary, I've grown plants using Actinic lighting with no problems at all. You can't have your cake and eat it too. On the one hand you seem convinced blue light is bad for plants yet you also recognize that chlorophyll has a high response to blue and red. So just exactly what is your argument and what have you yourself tested? I see a lot of references to the work of others but you yourself have not actually put this information to practical use or demonstrated the validity of these hypotheses within the context of aquatic plants. Our conclusions are based on the empirical evidence of our tanks, not solely on the basis of someone else's experiments performed in a petrie dish.

You're also glossing over the fact that most of the light that plants or algae are exposed to in this world is blue.
Additionally, the plants are never exposed only to blue. So whatever conclusion you wish to draw regarding shrinkage is irrelevant because there is no practical use of Dr. Bugbee's conclusion in our tanks.

Cheers,

 

[jaypeecee]

So just exactly what is your argument and what have you yourself tested? I see a lot of references to the work of others but you yourself have not actually put this information to practical use or demonstrated the validity of these hypotheses within the context of aquatic plants.

To date, I have simply been gathering information with the view of doing meaningful tests if and when I decide to purchase an Apogee SQ 520 PAR sensor. I have a perfectly adequate spectrometer. Aquatic lighting is a subject that interests me greatly. When the company, BML were in existence (now Omron Fluence), I designed the lighting fixture that is still over one of my tanks. Recently, I discovered that Dennis Wong also started out using BML lighting.

JPC

 

[jaypeecee]

You're also glossing over the fact that most of the light that plants or algae are exposed to in this world is blue.

No, I'm very much aware of that - for plants and algae in their natural habitat. But, we're trying to ensure optimum lighting for planted aquaria.

Additionally, the plants are never exposed only to blue. So whatever conclusion you wish to draw regarding shrinkage is irrelevant because there is no practical use of Dr. Bugbee's conclusion in our tanks.

I'm not drawing any conclusions about potential shrinkage caused by blue light. I'm simply asking questions on this forum and keen to hear what others have to offer. There may well be good reasons why Dr Bugbee's findings are not applicable to our tanks.

JPC

 

[jaypeecee]

Photosynthesis doesn't care about energy states.
Only photons.

Please tell us more.

Yea lots of blue light with little red can shrink internode elongation creating err stumpy stem plants but that is just a form not function thing. Not a matter of "health" Takes reef level of blue to do it though.

So, Dr Bugbee's comments about blue light may indeed be applicable to the aquarium environment? As I've never kept reef aquariums, can I assume that we would be unlikely to have sufficient PAR/PPF for blue light to be a problem?

JPC