# Fundamentals of Aquatic Lighting



## John P Coates (3 Aug 2014)

Hi Folks,

When we are trying to decide on the suitability of a particular lighting fixture for use in a planted tank including fish, what should we consider?  Some of the factors I can think of are as follows:

1 Light spectrum
2 Total light output in PAR
3 Ability to control light intensity
4 Energy efficiency
5 Colour Rendering Index (CRI)
6 Colour temperature (in °K)

Now, what is the relative importance of each - and why? 

Thanks.

JPC


----------



## ceg4048 (4 Aug 2014)

1. Light Spectrum is only a consideration for aesthetic reasons which, due to subjectivity, is not predictable.
2. Total Light output in PAR is the most important factor since this will determine the level of criitcality for CO2/flow/distribution.
3. Ability to control light intensity is the next most important factor based on item #2.
4. Energy efficiency is an economic issues and this therefore depends on the financial status of the hobbyist.
5. CRI is irrelevant and has no value.
6. Color Temperature is irrelevant and has little to no value.

Cheers,


----------



## clonitza (4 Aug 2014)

For me is a mix between #1 & #6 for aesthetics, if I like how it renders the color I stick on it, I don't care about something else since I run my tanks with T8s, they are enough to grow any plant and not too much to make my fish wanting to war sunglasses.

Cheers,
Mike


----------



## Edvet (4 Aug 2014)

clonitza said:


> not too much to make my fish wanting to war sunglasses.


----------



## John P Coates (4 Aug 2014)

ceg4048 said:


> 1. Light Spectrum is only a consideration for aesthetic reasons which, due to subjectivity, is not predictable.
> 2. Total Light output in PAR is the most important factor since this will determine the level of criticality for CO2/flow/distribution.
> 3. Ability to control light intensity is the next most important factor based on item #2.
> 4. Energy efficiency is an economic issues and this therefore depends on the financial status of the hobbyist.
> ...


Thanks for the feedback.

I cannot understand why you say that the light spectrum is unimportant. This challenges everything I've read on the subject. Since the photosynthetic spectrum clearly shows that plants absorb light mostly in the blue and red parts of the spectrum,  it makes sense to me that any light needs to ensure significant radiant energy at these wavelengths.

Surely CRI is very important for aesthetic reasons.  If the CRI is low,  say 30%, the plants and fish will take on a non-lifelike hue. Colour temperature will have a similar effect. If the lighting is 'warm', say 2700°K, the tank and its contents will look as though it is being illuminated by incandescent bulbs.  Not exactly representative of the natural light seen by tropical plants and fish.

JPC


----------



## GlassWalker (4 Aug 2014)

The light spectrum feeds into CRI and colour temperature, so they're kinda related. In essence the spectrum is the raw data, and the other two are numbers calculated from it. In my experience, colour temperature only seems to work where it is in the ball park of sunlight. It doesn't seem to work so well at very high values e.g. the tubes provided as standard with a Fluval Roma are rated at 18000k each but to me seem a fairly balanced white, not as blue as its value may suggest. I would also caution the colour temperature is a single axis, whereas you need at least two to describe colour. So it also falls down with unbalanced light spectrums. For example, the Interpet Tropical Daylight tube I find has a pink hue to it I don't like, and one of the Narva tubes is rather yellow-green strong which I don't like either. CRI is an imperfect measure of how filled out a spectrum is. Generally I find higher CRI ones look better, but recognise that is subjective.

I think efficiency has a contributing factor to running an aquarium. If the lighting produces a lot of heat, then depending on the aquarium design that heat may cause problems with water temperature. In the recent warm weather I'm glad I binned my T5s and T8s, and moved almost everything to LED now as I get comparable light output at much lower heat generation.

A question for all about PAR - Given the peak responses of chlorophyll in the red/blue regions of the spectrum, would a better measure not be to weight the measurement in those areas? E.g. if you had 1 unit of light in the green region, would that not grow plants slower than 1 unit total of a red/blue mix, assuming nothing else is limiting? This then ties in with efficiency. Taken to an extreme there are those red/blue lights used in hydroponics, but look really unnatural.

I'll also throw in another question about spectrum while I'm here. I vaguely recall reading in multiple places about how plant growth can change depending on the balance of red/blue light. I can't recall which way around it was, but biasing to one was claimed to increased growth, and biasing the other way encourages flowering/fruiting. I didn't look into this further at the time. Any comments on this?


----------



## Edvet (4 Aug 2014)

I know it's hard to let go off years of indoctrinating lighting spectrum, colour and CRI matter. It doesn't. There is more then enough energy in the foton's to use for the plants, they don't care about all these things. PAR is the king.
You can choose to not believe this, in that case i have some prime building grounds for sale in South america.................., or the Eifel tower for a reasonable deal..............


----------



## GlassWalker (4 Aug 2014)

I can see how PAR might work within certain limits and assumptions, but a better measure would reduce those uncertainties. Likewise with the colour temperature. Of course, you're welcome to say you don't need a better measurement for those, and what we have now is good enough. When I get interested in things, I like to know how everything works, even if it isn't necessary to function. It is likely I'm entering the region of diminishing gains for the effort expended. When I have time, I have some possible improvements to suggest on EI for example... although they depend on the validity of certain assumptions related to the process, but will save that for another thread.


----------



## John P Coates (4 Aug 2014)

GlassWalker said:


> I'll also throw in another question about spectrum while I'm here. I vaguely recall reading in multiple places about how plant growth can change depending on the balance of red/blue light. I can't recall which way around it was, but biasing to one was claimed to increased growth, and biasing the other way encourages flowering/fruiting. I didn't look into this further at the time. Any comments on this?


Hi GW, 

Many thanks for your reply. 

I have singled out one point you raised above. 

Yes,  I have also read about this. My recollection is that blue light encourages leaf growth whereas red light is important for fruiting. Chances are that I read about this in connection with horticulture rather than aquatic plants. I'll see if I can find a link. NASA were the first to show that potatoes could be successfully grown under a combination of blue and red LEDs. They wanted to see how to feed astronauts on board the ISS. Must be a welcome change after those pouches with attached straw!

JPC


----------



## Edvet (4 Aug 2014)

http://www.ukaps.org/forum/threads/spectrum-doesnt-matter-does-it.26717/


----------



## John P Coates (4 Aug 2014)

Edvet said:


> I know it's hard to let go off years of indoctrinating lighting spectrum, colour and CRI matter. It doesn't. There is more then enough energy in the foton's to use for the plants, they don't care about all these things. PAR is the king.
> You can choose to not believe this, in that case i have some prime building grounds for sale in South america.................., or the Eifel tower for a reasonable deal..............


Edvet, 

Please substantiate your statements about lighting. 

I fail to understand the relevance of your references to South America and the Eiffel Tower. 

JPC


----------



## James O (4 Aug 2014)

John P Coates said:


> Please substantiate your statements about lighting.



For informed debate, and as you raised the subject, please substantiate yours first (alternatively, please use the search function) Edit: or even easier now as the link has been posted



John P Coates said:


> I fail to understand the relevance of your references to South America and the Eiffel Tower



Humor fail 

Don't worry though its all above board. I took Edvet up on another offer and now own a lovely plot in Columbia and two amazing sculptures.  One a darling statue of a woman holding a flaming torch aloft and the other is of the Christ with his arms outstretched.  Its a shame he's so wide though as postage from South America now seems to be an issue


----------



## ceg4048 (4 Aug 2014)

Worrying about spectrum is really a waste of time and energy. What is demonstrated in a laboratory does not always translate to real world. There are many factors that have an effect on plant growth and health and each factor has a different magnitude of impact. As a result of aesthetics, subjectivity, art as well as the lighting industry itself, whatever advantages/disadvantages occur as a result of spectral distribution variation, these are obliterated by the orders of magnitude differences that result from the other factors in plant husbandry, such as, for example, flow/distribution/CO2 and PAR, which make about a 1000X difference to plant health than spectral distribution could ever dream of doing. Additionally, attempting to manage spectral distribution would be a complicated affair. Therefore, since the benefits of controlling spectrum is extremely low, while at the same time it's execution is very complicated, there is no point in taking this path because the path leads nowhere. We can grow excellent plants using any spectrum we want, and no one can declare, with any validity that the results of applying one spectrum is any better than the results of applying any other.

Color is an invention of the human mind only, therefore, parameters such as Color Rendering Index have no meaning in this application because one persons invention may not satisfy anothers. No one really cares if colors are accurate. The colors must be pleasing. Accurate and pleasing are mutually exclusive when it comes to art. Arguing about what color is more accurate or is better suited to plants is like arguing about what ice cream brand has more accurate or better flavor. Truly pointless unless the subject is fashion photography or crime scene forensic investigation.

The hobby is complicated enough and there are enough things to worry about  without complicating life further with things that don't matter.

Cheers,


----------



## clonitza (4 Aug 2014)

Edvet said:


> There is more then enough energy in the foton's to use for the plants, they don't care about all these things. PAR is the king.



Neither, the optimal light was "researched" a long time ago .. the old t8 tubes setup provide(d) everything that is(was) needed.
Later on the producers decided that this approach wasn't beneficial for their big pockets and threw in t5s, mhs and now leds. 
If algae had been traded on stock it would've bitten gold 10 times.


----------



## James O (4 Aug 2014)

True true, but now I can have much more control over multiple LED's now.  Thats the difference  

We had all the light we _*need.* _Now we have the light we _*want  - *_Nothing at all to do with plant health  

1) Get some lights (not too much mind you) 
2) Get on with it 
3) Stop worrying about it


----------



## John P Coates (4 Aug 2014)

It's a shame that one cannot ask a simple question on this forum without being either ridiculed or attacked in some way. I have never experienced this on any of the other forums that I regularly use. My participation in this community can only decline.

JPC


----------



## BigTom (4 Aug 2014)

John P Coates said:


> It's a shame that one cannot ask a simple question on this forum without being either ridiculed or attacked in some way. I have never experienced this on any of the other forums that I regularly use. My participation in this community can only decline.
> 
> JPC



Hi John,

I don't think anyone in this thread has intended to attack or ridicule you. Advice/discussion on here can be somewhat on the 'robust' side, but very rarely is it personal. Oh, and Edvet is Dutch, they can find humour difficult sometimes  (I know, my better half is Dutch).


----------



## GlassWalker (4 Aug 2014)

Thanks for the link to the previous thread on this subject. I'll have to have a more in depth read when I have more time. I'm not surprised the original question has come up before, but finding such content is another matter. This forum doesn't seem to be organised with topic FAQs as such. If these could be added, even if only linking to past threads, I think that would be helpful for relative newcomers like myself.

I'll also further add at this point, my goal is not to the best planted tank, but to understand the factors involved however small. The side effect should be I have a good planted tank in due course, but that is not my goal in itself.


----------



## Edvet (4 Aug 2014)

Now who's sleeping on the couch tonight........



BigTom said:


> they can find humour difficult sometimes


----------



## James O (4 Aug 2014)

BigTom said:


> Oh, and Edvet is Dutch, they can find humour difficult sometimes



Oh hell!  Does anyone want to split the statue of liberty with me or go halves on a timeshare in Columbia?


If you come to a question, don't post it - search it, under multiple phrases first.  You'll likely always get comedy or short replies if the answer already exists and someone has to constantly repeat themselves


----------



## GlassWalker (4 Aug 2014)

I think topic based FAQs as stickies in the appropriate sub-forum would help a lot.

I've never had much luck with forum based searches. I even get better results using google to search a given forum. Maybe I should search for The Matrix, but then again that might return too many hits!


----------



## BigTom (4 Aug 2014)

I have to admit that although this site runs tremendously well generally, the search function can be a bit hit and miss.


----------



## roadmaster (4 Aug 2014)

I belong to a couple other forum's where they still spend a dozen or more post's and several paragraphs for each opinion as to what constitutes proper spectrum for plant growth when ever the topic arises.(much of it regurgitated heresay or opinion vigourously defended)
I purchase T8 and T5 bulbs by the case for use in the building I work at as maint eng.
Have expierimented with many different spectrums of these bulbs on my planted affairs and can say that spectrum seem's much ado about nothing when comparison's were made in my tanks.
Intensity/Par are the determining factors in my tanks followed by what looks good to my eyes.
Weed's manage.


----------



## ceg4048 (4 Aug 2014)

BigTom said:


> I have to admit that although this site runs tremendously well generally, the search function can be a bit hit and miss.





GlassWalker said:


> I think topic based FAQs as stickies in the appropriate sub-forum would help a lot.



Hello,
           I agree that we should probably do a better job of "stickying"  some threads to make it easier to find.

It's true that there are a couple of limitations to the search function with this software.
The first big miss is that a minimum of 4 characters are required for words so searching, so that a 3 character word search such as "CO2" yields nothing. It might have bee implemented to stop people from searching common words such as "the" or "is" which could tie up the server due to number of occurrences. Powerful engines such as Google have no such limitations.
Another miss is that the engine does not allow exclusion of words, which would be a useful filter.

Lame as it may be, the search function is still a powerful tool if used correctly, so for example here are the search results. It took me 3 minutes to build the search and to execute it. It took me a LOT longer to write about it.:
http://ukaps.org/forum/search/3979746/?q=spectrum&t=post&o=date&g=1&c[title_only]=1&c[node]=50
using the following parameters:
Search phrase = "spectrum"
Search Titles Only Checkbox = checked
Posted by Member = null
Newer Than = null
Search this thread only = unchecked
Search this forum only = unchecked
Display results as threads = checked

You would have easily found the thread that was linked to earlier and a couple more - with additional links.

You can also confine the search to an expression if that expression is entered with quotes such as "excessive light" which returns a different list than if excessive light (without quotes) is entered. Without quotes, the engine returns hits with any of the words instead of only the ones with the the specific phrase.

By default, the "Search this forum only" box is checked, which if not paid attention to, and deselected, will overfilter the search.

Cheers,


----------



## ceg4048 (4 Aug 2014)

John P Coates said:


> I cannot understand why you say that the light spectrum is unimportant. This challenges everything I've read on the subject. Since the photosynthetic spectrum clearly shows that plants absorb light mostly in the blue and red parts of the spectrum, it makes sense to me that any light needs to ensure significant radiant energy at these wavelengths.


Unfortunately this is another false assumption made by almost everyone, and that is exactly why the comment challenges everything you've read on the subject. What you have read was not written by folks who investigated the specific function of plant pigments. They were told what to think and what to write, so they thought it and then wrote it.

The light harvesting mechanism of plants, algae and some bacteria, such as BGA consists of a central Chlorophyll complex. The complex, has, among many other components, a series of auxiliary pigments which respond to wavelengths of light other than blue and red. The energy captured by these pigments are then passed on to the Chlorophyll and therefore act as a spectral extension of the main Chlorophyll response curve. The leaf analyzes the spectral distribution and fabricates a variety of pigments to perform tasks, such as to reflect wavelengths that have too much energy, to absorb wavelengths that are not primary wavelengths and some pigments are even capable of changing the incident light to another color and reflecting it on to pigments that can then absorb the new color and pass it's energy on to the Chlorophyll.

It's a very sophisticated system and it doesn't need your help. Whatever spectral distribution you provide, the plant will determine how to best use that energy. In this hobby, it actually the opposite of what folks think. There is actually far too much light, that more often than not overwhelms the plants ability to quench the excessive energy.

So there is no demonstration that plants "...absorb light mostly in the blue and red..." It's simply that the Chlorophyll pigment itself has a higher response to blue and red but it depends on the other pigments to absorb the remaining wavelengths and to process those wavelengths. On the contrary, it is specifically because the Chlorophyll pigment has such a high response to blue and red that is is easily overwhelmed by blue and red. So if anything, what the photosynthetic spectrum shows is that you should be using LESS amounts of blue and red to reduce photo-inhibition. This fact has been completely misinterpreted for far too long.

Spectrum loving Klingons are a plague, a pestilence of misinformation on this planet. 
We are the cure.....

Cheers,


----------



## Andy Thurston (4 Aug 2014)

I've found that if i cant find something using the forum search. Using google and entering the same words followed by ukaps works quite well too, especially when searching for titles with lots of 3 letter words.

Can i use two and three letter words within the quotation marks eg. "Dan and andys crypt" or will the search disregard those too?


----------



## ceg4048 (4 Aug 2014)

Well I'm pretty sure it will ignore the 3 (or less) words in the phrase and just search for the 4 letter (or more) words in the phrase. That makes the phrase the same as not having quotes.

Regret to say that the Google technique you mentioned would be a better option...sorry....

Cheers,


----------



## GlassWalker (4 Aug 2014)

Does the ability to change the wavelength of light in the plant have a name? Sounds a bit like fluorescence, but I'm guessing it has a better name than that 

Photo-inhibition isn't something I thought about before either. I guess that raises a new question, how much light is too much? I haven't examined plants I have for their native conditions in the wild. As a rough estimate, I doubt anything we would realistically do on a tank would come anywhere near close to what direct sunlight could produce. Exceptions may include if water were naturally coloured, or if plants prefer shaded conditions.

And finally, I've barely started to unravel the matrix code. Don't make me learn Klingon too. Although it does seem an easier read than some plant biology texts...


----------



## X3NiTH (4 Aug 2014)

GlassWalker said:


> Does the ability to change the wavelength of light in the plant have a name?



Quantum Mechanics.

Apparently chromophores don't actually change the wavelength of light but are able to utilise the energy via Quantum Mechanics.


----------



## tmiravent (5 Aug 2014)

I've been learning (very slowly) important stuff about this hobby in this forum.
What 'Ceg4048' says (writes) were a cold bath for my mind.  (i was really convinced the opposite, marketing effects...)
The light questions about the Kº, spectrum, par, and other issues are well discussed here in the forum.
And made some experiments and concluded: 'Ceg4048' is really right!
This, more simple, way to think about light made me save a lot of money!
Color, temperature and spectrum is very important for me (for enjoying my tanks) and now i'm free to choose my light without a headache!

Other very useful advice I've learned: _this is not rocket science_ (read this a few times) . When i have some problem and start to build and solution if it turns too complex is because i'm missing the real point. Then a remember the sentence and try to focus on simple solutions. For me this is just a hobby.

*John, trying to answer your question:*
(My opinion)
- Light spectrum: very difficult to be objective. If there were a perfect spectrum would be the best for our tank?
I would worry about the final color result of the tank. The best spectrum is the one that fit's you.
- Total light output in PAR. It's already answered, the best way to measure what is important to plants. 
- Ability to control light intensity. Not a demand but flexibility is always a must. Can be important if you want to make different setup's with different tech plants. Daybreak, night fall and moon light can be very cool...
- Energy efficiency: for me is a demand! I use only LED, less heat and less cost!
- Colour Rendering Index (CRI): for water tanks i would forget this. The best CRI is our imagination!
- Colour temperature (in °K): very important for me. I use this as basic guide for building the colors in my tanks. (very warm, warm, neutral, cold).

Other considerations:
- shimmer effect, if you like and have some water agitation can be a must (can be achieved with LED)
- Lights with optics, can give dramatic shadows and concentrate the power in a smaller area. (like a led spot with 35º)
- Diffused light can give very soft shadows (like T5 or t8)


cheers


----------



## OllieNZ (5 Aug 2014)

GlassWalker said:


> Does the ability to change the wavelength of light in the plant have a name? Sounds a bit like fluorescence, but I'm guessing it has a better name than that
> 
> Photo-inhibition isn't something I thought about before either. I guess that raises a new question, how much light is too much? I haven't examined plants I have for their native conditions in the wild. As a rough estimate, I doubt anything we would realistically do on a tank would come anywhere near close to what direct sunlight could produce. Exceptions may include if water were naturally coloured, or if plants prefer shaded conditions.
> 
> And finally, I've barely started to unravel the matrix code. Don't make me learn Klingon too. Although it does seem an easier read than some plant biology texts...


From the Optimum Aquarium by Kaspar Horst and Horst E. Kipper 
(referring to readings taken is Sri Lanka) "The difference in lux was between fifty and ninety thousand lux"
Unfortunately they don't state the time of day they took the readings so the shaded areas receiving only 50 lux may have received more at some point during the day. They also point out that plants growing in the high light areas were in deep water (3.5m) or suffering from algae


----------



## ceg4048 (5 Aug 2014)

GlassWalker said:


> Does the ability to change the wavelength of light in the plant have a name? Sounds a bit like fluorescence, but I'm guessing it has a better name than that


Yes, it's called
Förster Resonance Energy Transfer (FRET)
It's not Florescence at all although it does occur in chromophores which are capable of fluorescence.



GlassWalker said:


> Photo-inhibition isn't something I thought about before either. I guess that raises a new question, how much light is too much?


Well it's really difficult to quantify because the amount of energy hitting the leaf starts a chain of events which then requires other components to complete the chain, principally, CO2 and then nutrients. In fact, this is called the Electron Transport Chain. Photosynthesis is a series of Reduction/Oxidation (Redox) reactions whose function is to deliver high energy electrons to strip CO2 of it's Carbon atoms in order to hydrate the Carbon into sugar. This final Carbo-hydration chemical reaction is not possible without the energy of the electrons. If carbon and other nutrients used in the sugar production are not available in sufficient quantities to match the amount of electrons being delivered the electrons which have nowhere to go spew out of control and poison the plant.

So how much light is "too much" has a relative answer and cannot be quantified unilaterally because as you can see, the answer depends on how much CO2 and nutrients the plants have access to. That, in turn, can depend on CO2 dissolution techniques as well as flow/distribution techniques.

A certain amount of PAR in one tank can be fine, but in another tank, the identical amount  of PAR can spell disaster. GENERALLY, what we advocate is that when a tank is first setup, the amount of PAR measured at the substrate should be in the neighborhood of 40-50 micromoles. Even so, as I mentioned, this guarantees nothing because CO2 must be excellent, flow/ distribution should be excellent, nutrient dosing should be excellent and maintenance should be excellent. If these items are satisfied then the probability of success is high.

So, as you can see, my point is that there are a LOT more things to worry about and which have a palpable effect on the health of the tank than what color the light bulb is. These factors are SO much more important than worrying about colors borders on the absurd.




GlassWalker said:


> I haven't examined plants I have for their native conditions in the wild. As a rough estimate, I doubt anything we would realistically do on a tank would come anywhere near close to what direct sunlight could produce. Exceptions may include if water were naturally coloured, or if plants prefer shaded conditions.


On the open unshaded areas of tropical forests, PAR values are approximately 2000 micromoles at the water's surface, however, the plants exposed to this value are also semi-exposed to atmosphere and therefore have access to CO2. Plants that are fully submerged are usually in murky waters where the PAR levels are a fraction of what it is at the surface. Other submerged plants have access to CO2 from organic sedimentary bacterial respiration or are fed by natural springs high in CO2.




GlassWalker said:


> And finally, I've barely started to unravel the matrix code. Don't make me learn Klingon too. Although it does seem an easier read than some plant biology texts...


Klingons are ever present. They are the ones who write most of the things you read in The Matrix.
Be strong.





Cheers,


----------



## James O (5 Aug 2014)

Plants had been dealing with light in it's various forms for millions of years before we decided to stuff them into glass boxes with T8/T5/LED's. Despite the various situations they find themselves in they still manage to cover most of our planet....

Bottom line?  Plants know more about light than we do.........so trust them


----------



## Marcel G (5 Aug 2014)

ceg4048 said:


> The leaf analyzes the spectral distribution and fabricates a variety of pigments to perform tasks, such as to reflect wavelengths that have too much energy, to absorb wavelengths that are not primary wavelengths and some pigments are even capable of changing the incident light to another color and reflecting it on to pigments that can then absorb the new color and pass it's energy on to the Chlorophyll.


Just a couple of days ago I studied this issue more deeply, and have found some studies/articles which supports Clive's claims. Here are few of them:
1) http://cpl.usu.edu/files/publications/poster/pub__3801011.pdf
2) http://pcp.oxfordjournals.org/content/50/4/684.full.pdf
3) http://www.ledgrow.eu/LightColor.pdf
It has been found that green leaves can absorb from 50 to 90% of green light! Also the green light has roughly the same quantum yield as the red one.


----------



## GlassWalker (5 Aug 2014)

Great links, although I've only scanned through them quickly for now.


----------



## tmiravent (5 Aug 2014)

Amazing 
So much information...
my brain hurts! 
I follow James O advice: 
cheers


----------



## Tim Harrison (5 Aug 2014)

Haha not this old chestnut AGAIN...

I'm confused cause all the papers linked by ardjuna state that not all wavelengths of photons are equally efficient in driving photosynthesis Doesn't this mean that at least some importance can be ascribed to light quality despite accessory pigments?

I may well have misunderstood, but I'm also confused as to Clive's assertion that there is no demonstration that plants '...absorb light mostly in the blue and red...'. Thomas Engelmann might disagree if he were still alive to do so. Look under the heading "Scientific Investigations" http://en.wikipedia.org/wiki/Theodor_Wilhelm_Engelmann Pretty elegant...huh

I also thought that a spectrophotometer could be used to measure the proportions of light of different wavelengths absorbed and transmitted by a pigment solution to similar effect But I may be wrong about that too, or maybe misunderstood its relevance

And isn't UV light the major cause of photoinhibition (defined as light induced damage) not visible wavelengths; although the latter is also obviously damaging too...especially blue wavelengths? And what about photosystem I - I thought that wasn't very susceptible to photoinhibition And isn't photosystem II damaged by light irrespective of intensity and Klingon's - haven't some studies concluded that low light intensity can be more damaging than high light intensity? And anyway, isn't the rate of damage directly proportional to the rate of repair so that photoinhibition very rarely impacts on plant health?

Those questions asked, maybe one of the reasons that flow and distribution are so important to us as aquatic plant growers is because lack of CO2 and nutrients can decrease the rate of repair and therefore have a negative impact on plant health. Maybe that's the main reason why achieving a balance between the various parameters - especially light - is so important, particularly at the beginning when the system has yet to stabilize...

And maybe it's one of the reasons why spectrum does matter especially with regard to adaptation to resource limitation, and say, the relatively expensive use of accessory pigments, and its subsequent impact on the rate of repair

My favorite quote...

'...Adaptation to resource limitation is a costly affair. Whether the plant invests in more chlorophyll or more enzymes it results in higher nutrient requirements and higher energy use. The higher energy use comes from the fact that proteins require constant maintenance in the cell to work properly and these maintenance processes absorb valuable energy and carbohydrates, which might otherwise be used for growth purposes...'

But obviously this need not necessarily be a problem in our aquariums where most of us go to great lengths to ensure that lack of light quality is compensated by an abundance of other resources, including light quantity.

SPECTRUM RULES


----------



## ceg4048 (6 Aug 2014)

Troi said:


> And isn't UV light the major cause of photoinhibition (defined as light induced damage) not visible wavelengths


Nope, absolutely not. That's just another Klingon argument. Just because UV causes photoinhibition it does not automatically mean that there is little or no effect from the visible light that we provide. Photoinhibition is constantly occurring, even when the lighting is low or moderate. It's the RATE of damage that increases with increasing intensity. Photosystem II takes the most damage specifically because it is extremely sensitive. Blue/Violet has the highest energy, so it does the most damage of the damage caused by visible light. So the plants have to repair the damage to the proteins that get damage by producing new replacement proteins.

Again, it's a really complicated system and so researchers have to be careful about the conclusions they draw. Here is a PubMed abstract ( http://www.ncbi.nlm.nih.gov/pubmed/12232146  ) discussing the recovery of terrestrial pea leaves:



> D1 protein turnover and restoration of the photochemical efficiency of photosystem II (PSII) after photoinhibition of pea leaves (Pisum sativum L. cv Greenfeast) acclimated to different light intensities were investigated. All peas acclimated to different light intensities were able to recover from photoinhibition, at least partially, at light intensities far above their growth light irradiance. However, the capacity of pea leaves to recover from photoinhibition under increasing high irradiances was strictly dependent on the light acclimation of the leaves; i.e. the higher the irradiance during growth, the better the capacity of pea leaves to recover from photoinhibition at moderate and high light. In our experimental conditions, mainly D1 protein turnover-dependent recovery was monitored, since in the presence of an inhibitor of chloroplast-encoded protein synthesis, lincomycin, only negligible recovery took place. In darkness, neither the restoration of PSII photochemical efficiency nor any notable degradation of damaged D1 protein took place. In low light, however, good recovery of PSII occurred in all peas acclimated to different light intensities and was accompanied by fast degradation of the D1 protein. The rate of degradation of the D1 protein was estimated to be 3 to 4 times faster in photoinhibited leaves than in nonphotoinhibited leaves under the recovery conditions of 50 [mu]mol of photons m-2 s-1. In moderate light of 400 [mu]mol of photons m-2 s-1, the photoinhibited low-light peas were not able to increase further the rate of D1 protein degradation above that observed in nonphotoinhibited leaves, nor was the restoration of PSII function possible. On the other hand, photoinhibited high-light leaves were able to increase the rate of D1 protein degradation above that of nonphotoinhibited leaves even in moderate and high light, ensuring at least partial restoration of PSII function. We conclude that the capacity of photoinhibited leaves to restore PSII function at different irradiances was directly related to the capacity of the leaves to degrade damaged D1 protein under the recovery conditions.



So basically what this is saying is that leaves that were originally grown in LOW light and then pummeled with high light do not recover and repair the photoinhibitive damage  as easily as leaves that were originally grown in HIGH light. This makes perfect sense to me, because the high light leaves already have developed a tolerance for high light so they can recover more easily from damage done to them at higher recovery light levels than the leaves that are accustomed to low light. People misinterpret this and draw the erroneous conclusion that "low light intensity can be more damaging than high light intensity?".



Troi said:


> I thought that wasn't very susceptible to photoinhibition


It's not as susceptible to damage due to light because it is not as sensitive to light.




Troi said:


> isn't the rate of damage directly proportional to the rate of repair so that photoinhibition very rarely impacts on plant health?


No, because the rate of repair is  inversely proportional to the light intensity. The rate of damage is directly proportiona to the PAR intensity.




Troi said:


> And maybe it's one of the reasons why spectrum does matter especially with regard to adaptation to resource limitation, and say, the relatively expensive use of accessory pigments, and its subsequent impact on the rate of repair


Again, no, because the total damage being done is related to the PAR intensity. Whatever proportion of damage is due to specific wavelengths you are not going to be able to control that anyway - but you can easily control the PAR, then you really don't need to worry about which wavelengths are causing more damage than others.



Troi said:


> I'm confused cause all the papers linked by ardjuna state that not all wavelengths of photons are equally efficient in driving photosynthesis Doesn't this mean that at least some importance can be ascribed to light quality despite accessory pigments?


As we mentioned ad nauseum, yes, there is some importance, but the magnitude of that importance is so small compared to the importance of other factors that for our purposes it becomes completely irrelevant. You will never solve any problem in your tank by changing the color of your bulbs and you will never see a difference in plant health or growth rate from one bulb to another. If that's not good enough for people then it means they prefer living in a dream world, which is exactly what The Matrix was created to do.

Cheers,


----------



## Tim Harrison (6 Aug 2014)

Hmmm...Clive I've decided that you're an Agent of the Matrix...a false profit attempting to divert us from the real Parousia. The real path to enlightenment lies with the acceptance that spectrum does matter - no matter how small or insignificant you consider it's influence in the context of our aquariums, and I think you've unintentionally confused the issue with all this photoinhibition malarky...

...Thomas Englemann must be spinning in his grave...


----------



## James O (6 Aug 2014)

From this I take:

'rate of repair is  inversely proportional to the light intensity. The rate of damage is directly proportional to the PAR intensity'

'Whatever proportion of damage is due to specific wavelengths you are not going to be able to control that anyway - but you can easily control the PAR, then you really don't need to worry about which wavelengths are causing more damage than others'

As we can't control the nm spectrum each bulb/LED produces we are stuck with controlling intensity (PAR).  Even if we could, you would still have spill of various spectrums of light available from other bulbs for other plants, daylight from the window and room lighting.

I think in the real world of my tank, where plants are not grown as isolated specimens under specific lights, the amount of light is more important than the colour


----------



## John P Coates (6 Aug 2014)

OK,  we have said a lot about plants, which is not surprising. This is the UKAPS forum, after all. But, in my original question, I also asked about fish. I read an interesting article a few months ago about vision in fishes. If you're interested,  here it is: 

http://en.m.wikipedia.org/wiki/Vision_in_fishes

It would suggest that, from a hobbyist's point of view, UV light may be important, particularly in breeding tanks. From an aesthetic perspective, we generally like to ensure that the colours of a fish are 'picked out'. But, for me, I don't want to fit filters on my specs to prevent individual colours being burned onto my retina! I've seen tanks where the level of blue and red light have been 'turned up' so much that you would have been able to see these fish (often neon tetras) on the ISS! As I'm writing this, I seem to recall that, unlike marine fish, freshwater fish have few, if any, colour pigments. I need to check this out. Time to do some digging… 

JPC


----------



## Tim Harrison (6 Aug 2014)

James O said:


> From this I take:
> 
> 'rate of repair is  inversely proportional to the light intensity, they're not necessarily interchangeable terms. The rate of damage is directly proportional to the PAR intensity'
> 
> ...



You're right. Spectrum isn't really important in terms of photoinhibition in our tanks (although UV light is far more damaging than visible light - despite what Clive states).

What is important is maintaining optimum environmental conditions so that repair keeps apace with photodamage...you know the usual - flow, distribution, nutrients and CO2...Under those conditions repair is so rapid that it isn't usually outpaced by photodamage even under very high light intensity. And that's not mentioning the array of other protective mechanisms plants employ.

So in other words given an abundance of other resources, and therefore lack of environmental stress, photoinhibition is not something we need worry about at all...and it's really a bit of a red herring - if it weren't Earth would still be a barren plant with a few chemoautotrophs, wallowing in primordial soup, for company.

Spectrum (quality of light) on the other hand is important to the health of all higher plants (even aquatic ones), not just in terms of growth rate but in terms of plant morphology, reducing the impact of resource limitation, and triggering life-cycle processes.

However, it's not usually a concern for us because we all tend to use full spectrum bulbs that provide plants with the quality and quantity of light they require. Luckily we also find them aesthetically pleasing. It's a function of the fact that the photosynthetically active spectrum and the visual spectrum are one and the same give or take a few nm; which is a happy coincidence of evolution.

However, my assertion has always been that the unqualified statement "spectrum doesn't matter" has the potential to mislead, and that given the above light quality is perhaps more important to us as aquatic plant growers than we realize. But don't just take mine or Clive's word for it Google's Scholarly Articles is an amazing resource...


----------



## ceg4048 (6 Aug 2014)

James O said:


> I think in the real world of my tank, where plants are not grown as isolated specimens under specific lights, the amount of light is more important than the colour


Yes, this is exactly the point. I can't see why Troi insists on expending energy on factors that are insignificant. There is more than enough of all frequencies in the light bulbs we use - regardless of the type/technology or even Kelvin temperature of the bulb. Whether it's T8, Halide or LED, plants have no trouble getting enough Red or Blue. So why worry about replacing a bulb that has 3X more red than you need with a bulb that has 5X more than what you need?

Here's an example: This is the relative spectral energy distribution of a typical Grolux bulb. These were quite the rage some years ago because of this distribution: The marketing department extolled the virtues of the Red and Blue peaks waxing poetic about how closely they matched the Chlorophyll absorption spectrum. There were never any reported improvements in performance for aquatic hobbyists. People using these bulbs got just as much algae as anyone else and the virtues of these bulbs could never be proven - and that's because no one was paying attention to the things that matter more than spectral distribution. What's more, if you use these bulbs exclusively your tank will look like total crap because they have a horrible, sickly purple hue.





Having said all that, what we stated in earlier post in this and other threads is that if you want your fish and plants to look more pimped with red then use these bulbs in combination with other color bulbs.
Here is a plant growing under 6500K bulbs. How boring, how bourgeois:





With the substitution of a grolux type bulb mixed in with these boring bulbs, the look of this plant can be embellished without negatively impacting the overall look. The plant didn't grow any faster and wasn't any healthier, but it looked a whole lot prettier (in my opinion).





So this is the importance of color. It allows you to paint your tank with whatever visual idea inspires you. That's NOT insignificant. The path to enlightenment comes from knowing what matters and what doesn't. It comes from understanding when you are free to choose options unconditionally, knowing that you are not restricted to someone elses dreamy personal vision of what reality ought to be.




Troi said:


> Hmmm...Clive I've decided that you're an Agent of the Matrix...a false profit attempting to divert us from the real Parousia.


Did you know that The First Matrix was designed to be a perfect human world, where none suffered, where everyone would be happy?
It was a disaster, no one would accept the program, entire crops were lost.
Some believed we lacked the programming language to describe your "perfect world", but I believe that as a species human beings define their reality in terms of misery and suffering.
Which is why The Matrix was redefined to this, the peak of your civilization.

Cheers,


----------



## ceg4048 (6 Aug 2014)

Troi said:


> Spectrum isn't really important in terms of photoinhibition in our tanks (although UV light is far more damaging than visible light - despite what Clive states).


Troi did you actually read the data in link you yourself supplied?
It clearly states:


> *Photoinhibition* is light-induced reduction in the photosynthetic capacity of a plant, alga, or cyanobacterium. Photosystem II (PSII) is more sensitive to light than the rest of the photosynthetic machinery, and most researchers define the term as light-induced damage to PSII. In living organisms, photoinhibited PSII centres are continuously repaired via degradation and synthesis of the D1 protein of the photosynthetic reaction center of PSII. Photoinhibition is also used in a wider sense, as dynamic photoinhibition, to describe all reactions that decrease the efficiency of photosynthesis when plants are exposed to light.



Further, it states:


> Photoinhibition occurs in all organisms capable of oxygenic photosynthesis, from vascular plants to cyanobacteria. In both plants and cyanobacteria, blue light causes photoinhibition more efficiently than other wavelengths of visible light, and all wavelengths of ultraviolet light are more efficient than wavelengths of visible light.



...and...


> Photosystem II is damaged by light irrespective of light intensity. The quantum yield of the damaging reaction in typical leaves of higher plants exposed to visible light, as well as in isolated thylakoid membrane preparations, is in the range of 10−8 to 10−7 and independent of the intensity of light. This means that one PSII complex is damaged for every 10-100 million photons that are intercepted. Therefore, photoinhibition occurs at all light intensities and the rate constant of photoinhibition is directly proportional to light intensity.



So the fact that UV causes more damage than visible light is not relevant. The relevant fact is that visible light causes photoinhibition and that blue light causes more damage than the other wavelengths.

So why is spectrum a red herring in terms of photoinhibition, even though it has actually been measured and quantified, but not a red herring in terms of plant growth and health, which has never been measured or quantified?

You are confusing the issue, because what I stated was that too much PAR is the cause of damage to plants when the nutrient and CO2 levels are insufficient. The mechanism of the damage caused by too much PAR are photoinhibition, where the recovery of the proteins occur at an insufficient rate and photorespiration which is a mechanism that attempts dissipates the toxic effects of reactive oxygen species.

Cheers,


----------



## Doug (6 Aug 2014)

Blimey..........all a bit too much for me.

All I want to do is grow some plants and see some fish....

Think I'll happily continue with my Pro-tropical and Grolux 54W T5's and watch my healthy plants continuing to grow....and see the pretty colours on the fish..


----------



## Tim Harrison (6 Aug 2014)

ceg4048 said:


> Yes, this is exactly the point. I can't see why Troi insists on expending energy on factors that are insignificant. There is more than enough of all frequencies in the light bulbs we use - regardless of the type/technology or even Kelvin temperature of the bulb. Whether it's T8, Halide or LED, plants have no trouble getting enough Red or Blue. So why worry about replacing a bulb that has 3X more red than you need with a bulb that has 5X more than what you need?
> 
> Here's an example: This is the relative spectral energy distribution of a typical Grolux bulb. These were quite the rage some years ago because of this distribution: The marketing department extolled the virtues of the Red and Blue peaks waxing poetic about how closely they matched the Chlorophyll absorption spectrum. There were never any reported improvements in performance for aquatic hobbyists. People using these bulbs got just as much algae as anyone else and the virtues of these bulbs could never be proven - and that's because no one was paying attention to the things that matter more than spectral distribution. What's more, if you use these bulbs exclusively your tank will look like total crap because they have a horrible, sickly purple hue.
> 
> ...



I'm sure that's what I said...isn't it?



ceg4048 said:


> Troi did you actually read the data in link you yourself supplied?
> It clearly states:
> 
> 
> ...



Didn't I just say something similar to that as well?

Clive as usual I couldn't disagree with you less...except I'm sure I've read several peer reviewed papers quantifying the effect of spectrum on plants...

I just don't think photoinhibition is relevant at all - whether caused by blue light, UV radiation, or pink polka dots, or quantified or not - since in all but the most extreme cases repair is so rapid photodamage is outpaced, even under very high light intensity.


----------



## John P Coates (6 Aug 2014)

"The path to enlightenment comes from knowing what matters and what doesn't. It comes from understanding when you are free to choose options unconditionally, knowing that you are not restricted to someone elses dreamy personal vision of what reality ought to be".

And I thought this was a forum about aquatic plants!

JPC[DOUBLEPOST=1407333574][/DOUBLEPOST]Hi Folks,

As I said in post no.41, I would welcome feedback from those people who also have an interest in fishkeeping.

JPC


----------



## roadmaster (6 Aug 2014)

I have a keen interest in keeping fishes and have been doing so for the last forty years.
Can say with fair amount of certainty that fish could care less if there is any light at all.They don't care if the tank is tea stained from tannins or cloudy as soup.
Lighting is for our pleasure mostly and plant growth.


----------



## John P Coates (7 Aug 2014)

roadmaster said:


> I have a keen interest in keeping fishes and have been doing so for the last forty years.
> Can say with fair amount of certainty that fish could care less if there is any light at all.They don't care if the tank is tea stained from tannins or cloudy as soup.
> Lighting is for our pleasure mostly and plant growth.


Hi Roadmaster,

There is no doubt that fish can tolerate cloudy water and some South American fish live in water that looks like tea. However, the behaviour of fish is affected both by light intensity and colour. Take a look at this fascinating article:

http://hastingszidana.blogspot.co.uk/2007/01/fish-behaviour-and-light.html

Or:

http://www.tropicalfishkeeping.com/...s/lighting-how-affects-freshwater-fish-81982/

Happy reading!

JPC


----------



## Tim Harrison (7 Aug 2014)

Interesting articles. Whilst experimenting with different colored LEDs I witnessed some fairly striking behavior between a pair of mature angel fish that had coexisted very peacefully since they were no larger than a twenty pence peace. Going through the spectrum they were fine until I got to blue. As the intensity of blue increased - the female, I think - began to attack the male viciously pecking his flank. Obviously, I immediately changed the color and miraculously peace was instantly restored. I'm guessing that she didn't recognize him under the extreme blue light and felt the need to establish a pecking order? So IME light can have a very profound effect on fish.


----------



## roadmaster (7 Aug 2014)

Well I know the author of the second article well (hope he is well also) and agree with the impact of sudden lighting over the tank as witnessed by myself with several species.(fishes are easily spooked)
Is why I have light in room an hour before lights over the tank come on.
Other tanks I have kept fish in for their lifespans had no light other than ambient light in the room and noted no odd behavior or reduced fry hatches as the theory presented by first author suggests.
Have also noted all manner of tropical's even surface orientated  species forage along the bottom of the tank in total darkness.This was influenced more by sparse feedings in heavily populated tanks than perhaps lighting or lack thereof but the fishes thrived regardless. they got fat,re-produced,and often were more active than when lighting sent them scurrying for the wood,rocks,plants.
Scent,Phermones,and movement detected by lateral line on fishes also help them overcome poor lighting while feeding witth many species as evidnced by the fishes I catch at night along the river banks and upon lakes near my home.
Anyhow I have yet to see any fishes that really enjoy the often mega lighting that some throw over their tanks.
Still believe the fishes could care less.


----------



## roadmaster (7 Aug 2014)

Troi said:


> Interesting articles. Whilst experimenting with different colored LEDs I witnessed some fairly striking behavior between a pair of mature angel fish that had coexisted very peacefully since they were no larger than a twenty pence peace. Going through the spectrum they were fine until I got to blue. As the intensity of blue increased - the female, I think - began to attack the male viciously pecking his flank. Obviously, I immediately changed the color and miraculously peace was instantly restored. I'm guessing that she didn't recognize him under the extreme blue light and felt the need to establish a pecking order? So IME light can have a very profound effect on fish.



Yes,I have seen females cichlids of a few species select the best colored male and reject the poor presentation of colors by other males (often subdominant ones ).
IME larger female cichlids of many species will seldom select or allow mating with smaller males or subdominant males that often try to remain drab colored so as not to draw attention from other dominant males.
Hard to determine sex in some species(Angelfish in particular) outside breeding time and what you witnessed could have been just coincidence.
Would repeat the test a few times before I would feel comfortable declaring any profound affects the lighting may or may not have played.
Could be the fishes were just adjusting the pecking order and or letting the other know that their attentions were not welcome.
Just my theory so long as that is what we are considering.


----------



## Tim Harrison (7 Aug 2014)

Thanks for the info, I'm not so clued up on cichlid behavior. Sure it could have been coincidence, and obviously it's only anecdotal, but I raised these fish and had never witnessed such behavior before or since. 

I know I'm anthropomorphizing but if ever a fish looked totally shocked and tragically emotionally wounded it was this unfortunate male Angel fish. Females...can't live with 'em...can't live with 'em...


----------



## John P Coates (7 Aug 2014)

roadmaster said:


> Anyhow I have yet to see any fishes that really enjoy the often mega lighting that some throw over their tanks. Still believe the fishes could care less.


Some fishes do not seem to object to intense lighting but others are clearly less than happy with this. However, plants and hiding places (caves, etc.) provide plenty of shade. In my current tank, it is apparent that Dwarf Gouramis and Gold Barbs do not object to lots of light. On the other hand, Gold Rams and Rosy Tetras are less happy with this scenario. I think it may have some bearing on fishes being classified as top, medium or bottom dwellers. So, I think the fish do care about the amount of light but it's no big deal because they find somewhere in the tank where they feel comfortable and rest their weary fins!

 JPC


----------



## Tim Harrison (7 Aug 2014)

It depends on the environment in which the species evolved. For instance, the natural habitat of many tetras tends to be heavily shaded TRF tributaries, where the water is typically acidic, of negligible carbonate hardness and conductivity and stained brownish due to the presence of humic substances released by decomposing organic matter. To quote Seriously Fish. As a consequence, the substrate tends to be covered in fallen branches, tree roots and leaf litter, and usually devoid of aquatic vegetation. 
Conversely, the natural habitat of many danio and barb species is unshaded and supports dense growths of aquatic plants. 
I think if you want to see your fish at their best biotopes are always a good option. Otherwise different species will tolerate the environment you provide but not necessarily thrive in it...


----------



## Edvet (8 Aug 2014)

Troi said:


> Conversely, the natural habitat of many danio and barb species is unshaded and supports dense growths of aquatic plants.


 You have any links for this Troi?


----------



## Tim Harrison (8 Aug 2014)

Ok...maybe it was an over generalization...perhaps I should have said some danio and barb species, and then given examples to illustrate the point I was trying to make...picky


----------



## roadmaster (13 Aug 2014)

I agree with Troi that biotopes often provide fishes with environment they can feel most comfortable in  not unlike people .
Take for example In my neck of the woods, there are three types of folks.
Ridge runner's  (hill folk or mountain folk),Plow  Jockey's (Farmers) and River rats (they got webbed feet).
All have carved out a niche and the three seldom are found together unless they should be fishing from the same boat on the weekends, or vying for the affections of the same female(s) Much fireworks then.
They just feel more comfortable in their own environment where they have learned to thrive on what nature provides in that particular environment.


----------



## Troglodyte (19 Sep 2014)

Well I am on my days off and popped in to see what is happening, haven't been in for a while. However found the lighting threads as interesting as always!   I did note that while I was reading some lighting research in a past job I came across a lot of information that confirms lighting can act as a trigger to fish spawning, reducing stress and changing fish behaviour. So may be something that needs to be considered for your setups? I was surprised to hear from Troi the effects of blue in Angels, as it is well researched that blue is one colour that tends to be relaxing for fish such a tilapia and if used will allow overcrowding to higher stocking levels, without inducing stress.  Also contrary to popular believe using red light tends to make fish aggressive and creates stress!! Would you believe it? Seems to go against all I learnt about using red light to acclimitise new fish on arrival   You learn something new every day eh? I can only hope that the fact that all f ish may respond to colours differently may have worked in my favour then..


----------

