Fundamentals of Aquatic Lighting

[John P Coates]

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]

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'

'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

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]

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.

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]

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]

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]

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.



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,

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

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


Further, it states:


...and...


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,

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]

"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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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..