# Enough Light?



## ceg4048 (12 Sep 2011)

Hi,
    For the 1000th time, why would you want to add more light if you're getting algae using the lights that you have now?

Light causes algae, and so adding more light causes more algae.

There is no rule that says you must use high light just because you are using CO2, but there is a rule that says you must use CO2 if you have high light.

Cheers,


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## ceg4048 (12 Sep 2011)

Hi mate,
              Well the plants will answer the question, really. My rule of thumb is that if you have enough light for algae to grow then you have enough light for plants to grow. The only difference adding more lights will make is that you plants will grow faster - and that also means algae can grow faster.

It's not possible to accurately gauge the lighting level just from the wattage and tank size. The real measure of lighting energy is based on PAR. This is the only objective measurement of enough, not enough or too much light.

Cheers


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## ceg4048 (13 Sep 2011)

Ok, let me try to explain it another way. Lets say you're in the UK and you buy a 60 watt light bulb. In order to produce the amount of light the designers intended it must be inserted into a lamp connected to a 240 volt electrical outlet. Then imagine you take the lamp over to the USA where the voltage is 120 volts. What happens when you turn on the lamp? Answer...the bulb looks very dim. Imagine the lamp is plugged in to an outlet of only 60 volts.When you turn on the lamp you'd barely be able to see the filament glow. At some point if you kept reducing the voltage the bulb filament would not glow at all. There is some voltage limit below which the bulb doesnt work. As long as you keep the voltage above this "threshold" the filament will glow, but the higher the voltage the brighter and hotter the bulb will get.

The job of the bulb is to convert electrical energy to light energy. The job of the plant is to convert light energy into electrical energy. The plant is a generator, and the more light it gets the more electricity it generates. Like the bulb, there is some minimum amount of light it required, below which, insufficient electricity is generated.

This minimum value of light energy is called The Light Compensation Point. It is the point at which the electricity consumed by the plant is exactly equal to the amount of electricity generated by the plant. If the available light energy is below this point the plant cannot grow and will waste away to nothing. If the available light energy is exactly equal to this point the plant will not die but it cannot grow (it's producing just enough electricity to stay alive). 

So, as long as the available light energy exceeds the LCP the plant can produce enough energy to grow assuming that the available Co2 and nutrients can support the rate of growth commanded by the electricity being generated.

Above LCP, plant health therefore is only dependent on CO2 and nutrients. If the light energy exceeds the available CO2/nutrient level then the plant becomes unhealthy and algal spores will bloom. So there is no way that insufficient light can cause algae. This can only happen due to excessive light.

If your plants are growing then this automatically means that you have more than the minimum required light for survival and if you have algal blooms then this automatically means you have too much light whichcauses a decline in plant health.

It's entirely possible to have excellent plant health with very low light, unless the light is below the LCP. This is confirmed by the existence of healthy low tech tanks.

Cheers,


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## frankzappatistas (19 Sep 2011)

ceg4048 said:
			
		

> This minimum value of light energy is called The Light Compensation Point. It is the point at which the electricity consumed by the plant is exactly equal to the amount of electricity generated by the plant.





> from wikipedia (http://en.wikipedia.org/wiki/Compensation_point)
> 
> The compensation point is the amount of *light intensity *on the light curve where the rate of photosynthesis exactly matches the rate of respiration. At this point, the uptake of CO2 through photosynthetic pathways is exactly matched to the respiratory release of carbon dioxide, and the uptake of O2 by respiration is exactly matched to the photosynthetic release of oxygen.



Wikipedia refers to *light intensity*, that means that the photo period is irrelevant? There is an article somewhere in http://www.aquajournal.net that refers that photosynthesis starts after 4-5 hours from the moment the lights switched on. 

Considering all the above mentioned,  can someone conclude, that extended photo period to 8-10 hours could not encourage algae growth considering that the intensity of light is in line with compensation point and enough nutrients and Co2 are provided?

Thanks for the information


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## clonitza (19 Sep 2011)

I wouldn't trust aquajournal 100% about plant growth. 
I think Ceg is encouraging us to think and act more on plant growth and not spend our efforts fighting algae, thus avoiding algae blooms. You can't eliminate all the algae in the aquarium even with everything in check (light, ferts, co2, flow, distribution) but you can slow their development if all the plants are thriving. If you don't want any algae just buy 1-2-grow plants and keep your aquarium in a lab controlled environment. 

Mike


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## frankzappatistas (19 Sep 2011)

clonitza said:
			
		

> You can't eliminate all the algae in the aquarium even with everything in check (light, ferts, co2, flow, distribution) but you can slow their development if all the plants are thriving. If you don't want any algae just buy 1-2-grow plants and keep your aquarium in a lab controlled environment.
> Mike



I know that nobody can eliminate algae, that was not the reason of my question.
My lack of experience and so many conflicting information around the Internet make me confused and I' m trying to clarify some things.


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## clonitza (19 Sep 2011)

I know what you feel, I've been there myself.
I'm not a scientist but I can tell you form my current knowledge that you can fight algae blooms using a few lighting tricks:

- lower the intensity (turn off some tubes, take the reflectors out) or,
- lower the photoperiod to a couple of hours a day or,
- break your photoperiod (my low tech schedule: 2h light - 3h break - 2h light - 3h break - 2h light / 60l using 3x15w T8 / TNP+ & EasyCarbo 1ml per day)

Also work on optimizing the ferts regime, CO2, water flow & distribution etc. Use maybe EI for a while and do large weekly water changes.

For the algae in your HC (if you still have it) you can use Easy Life Algexit, it doesn't kill it instantly so you must have a little bit of patience ~1 month or so. It doesn't have side effects as far as I've tested nor on fish (fry included) or plants. Anyway don't rely only on this, try also to improve plant growth.

Mike

Sorry for the off topic.


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## frankzappatistas (19 Sep 2011)

That's what I'm doing right now, except of the Algexit, and waiting.

But in the meanwhile it is not a bad idea to try and learn something more.

Thanks anyway, advice much appreciated   .


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## bogman (19 Sep 2011)

this post is one of the best , clearest descriptions of the light needs of an aquatic plant in an aquarium,  a must read for all those swimming in murkey waters of what needs to sit above our aquariums


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## madlan (19 Sep 2011)

I used to worry about excess nutrients etc causing algae as it had always been a problem in the past. With my current setup I followed advice from various people here and now have a High Tech fast growing setup that's algae free, I don’t even clean the glass 

Lots of nutrients, lots of Co2, good flow and enough light. I don't test anything now (except for Co2 via drop checker). The only real maintenance is the weekly water change so even though its "High Tech" I've never had it so easy


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## ceg4048 (19 Sep 2011)

frankzappatistas said:
			
		

> Wikipedia refers to *light intensity*, that means that the photo period is irrelevant? There is an article somewhere in http://www.aquajournal.net that refers that photosynthesis starts after 4-5 hours from the moment the lights switched on.


Err..no, that's absolutely incorrect, however, higher plants take longer to "spool up" their machinery of photosynthesis than do algae, which have much simpler mechanisms. The first light dependent reactions begin immediately but there are thousands of reactions in total.



			
				frankzappatistas said:
			
		

> Considering all the above mentioned,  can someone conclude, that extended photo period to 8-10 hours could not encourage algae growth considering that the intensity of light is in line with compensation point and enough nutrients and Co2 are provided?


No, this is an incorrect conclusion. Firstly, the LCP of each plant is different. Plants we call 'low light" such as mosses, ferns and so forth, have a lower LCP than stem plants, for example. Secondly, the photo reactions have a limited time span in higher plants. 8-10 hours is about the limit. After that the plants start to shut down. Algae on the other hand are opportunists and they can happily continue all day, so algae will continue to produce food while the plants have closed up shop. Extended lighting periods therefore have an impact by encouraging algae.

The way we think about light is the reason we have so much difficulty understanding it's impact. When we see light it appears to us as a continuous ray or stream of brightness, but this is not the truth of light. light is actually a series of individual pulses, in a way, like raindrops. A low intensity light is like a light rain falling gently on a leaf. A high intensity light is like a torrent, and just like a storm, high intensity light does damage to the plant photo cells as they collide with the cells.

So intensity is much more important than duration because the intensity determines the number of collisions the light particles make with the the photo receptors in the leaf. If the intensity is too weak, i.e. the number of collisions is too low, the receptors cannot make enough use of the energy. if the intensity is too high then the receptors are bombarded and actually are destroyed by the bombardment. So now, within this context, think about duration. The photoperiod will only have relevance depending on the intensity. With insufficient intensity the photoperiod has no meaning because the plant cannot make use of the weak energy and at the same time it is respiring (using energy). If the intensity is too high then the damage to the cells is occurring for a longer time, but whether short duration or long duration, damage is being incurred.

There is a phenomenon called "photoinhibition" which is a stalling of photosynthesis, and which occurs all the time that the light is on, simply because the light particles raining down on the plant inevitably damages some of the chlorophyll cells. If the rate at which collisions occur (intensity) is modest, then the plant is able to manufacture and release enzymes that repair the cells. If the collision rate is too high then more damage occurs than can be repaired by the plant in a given time period. It's entirely possible that the colors we see in plants under high lighting are a direct result of the plants attempt to minimize the rate of photoinhibition by reflecting (or fluorescing) some of the light energy it is being pummeled with.

Cheers,


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## frankzappatistas (20 Sep 2011)

Thanks for the information mate, that clarifies many things.


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## gmartins (20 Sep 2011)

ceg4048 said:
			
		

> There is a phenomenon called "photoinhibition" which is a stalling of photosynthesis, and which occurs all the time that the light is on, simply because the light particles raining down on the plant inevitably damages some of the chlorophyll cells. If the rate at which collisions occur (intensity) is modest, then the plant is able to manufacture and release enzymes that repair the cells. If the collision rate is too high then more damage occurs than can be repaired by the plant in a given time period. It's entirely possible that the colors we see in plants under high lighting are a direct result of the plants attempt to minimize the rate of photoinhibition by reflecting (or fluorescing) some of the light energy it is being pummeled with.



I've seen a tank (in a portuguese forum - aquariofilia.net) and the guy was using massive amounts of light in a very shallow tank. Glosso was red   . I had never seen red gloss before, but that was exactly my thought. It's getting so much light that it is getting burnt. So this makes totally sense. That's why maybe a lot of stem plants only get red on the upper tips where light intensity is stronger so to cause photoinibition.

If I recall well, the colour we see is just what is not absorbed by an object and it is hence reflected. If we see red, then this means plants are no longer absorbing this part of the spectrum???

cheers,

GM


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## niru (20 Sep 2011)

ceg4048 said:
			
		

> The way we think about light is the reason we have so much difficulty understanding it's impact. When we see light it appears to us as a continuous ray or stream of brightness, but this is not the truth of light. light is actually a series of individual pulses, in a way, like raindrops. A low intensity light is like a light rain falling gently on a leaf. A high intensity light is like a torrent, and just like a storm, high intensity light does damage to the plant photo cells as they collide with the cells.
> 
> So intensity is much more important than duration because the intensity determines the number of collisions the light particles make with the the photo receptors in the leaf. If the intensity is too weak, i.e. the number of collisions is too low, the receptors cannot make enough use of the energy. if the intensity is too high then the receptors are bombarded and actually are destroyed by the bombardment. So now, within this context, think about duration. The photoperiod will only have relevance depending on the intensity. With insufficient intensity the photoperiod has no meaning because the plant cannot make use of the weak energy and at the same time it is respiring (using energy). If the intensity is too high then the damage to the cells is occurring for a longer time, but whether short duration or long duration, damage is being incurred.



Hi Clive

in light of your above statements, would it be accurate to think that plants need an optimal total amount of light above their LCP per day (think of number of light quanta of appropriate frequency, per unit area/amount of photosynthetically active leaf mass, per day)? Then the main question is to appropriately "distribute" these quanta in the intensity (photons/unit time) - versus - light-period (total exposure time). As you mention, the 2 ends of the possibilities are: a single burst of light (will lead to too much damage of cells by heavy bombardment), & uniform light for a given "day"-period ON-time (which is hopefully more than the LCP for THAT frequency). Plants that have higher number of cell-repair medics/mechanisms per vulnerable-to-destruction photocell will then be able to withstand high intensity doses better than others. That could explain the "better" growth & light intensity response of "high light" plants. In nature, the sun's motion in sky (& hence the intensity control per say) dictates this "optimum" growth (or the best light distribution in the intensity-Vs-period as mentioned above) for a given plant.  

Of course one has to be optimal for all frequencies in the light spectra available. So perhaps a warm day-light tube has a different best-growth mode than a bluer light tube. One can then tamper his light periods & intensity differently for different tubes in different manner to achieve a healthy tank. [In nature, for e.g. when sun is closer to horizon its much redder (lower freq) than when its overhead (when relative fraction of high-freq light increases per given amount of sunlight).

Would aquarium plants fare better if such controls are set-in? Moreover, does it make sense of having high-light & low-light plants in the same tank, or that it would explain why some plants do better than others? Are there any works in literature on this? 



			
				ceg4048 said:
			
		

> There is a phenomenon called "photoinhibition" which is a stalling of photosynthesis, and which occurs all the time that the light is on, simply because the light particles raining down on the plant inevitably damages some of the chlorophyll cells. If the rate at which collisions occur (intensity) is modest, then the plant is able to manufacture and release enzymes that repair the cells. If the collision rate is too high then more damage occurs than can be repaired by the plant in a given time period. It's entirely possible that the colors we see in plants under high lighting are a direct result of the plants attempt to minimize the rate of photoinhibition by reflecting (or fluorescing) some of the light energy it is being pummeled with.



Are algae also affected by this bombardment for they too have similar light-->chemical energy transition mechanism? If so, then, just as blackouts are used to starve & kill algae (since they cant store food), would high irradiation also work?? Of course plants will suffer as well, but given their regeneration capacities, and food storage possibilities, they might survive?? Particularly if a lightly planted tank is suffering from BGA or mssive BBA invasions, then balckouts followed by irradiation dazzle the heck out of algae? And, more importantly, would it be better than simple blackouts alone?

BTW: Dont the UV-filters try to achieve something similar like this?? 
-niru


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## ceg4048 (20 Sep 2011)

*Re: Re: Enough Light?*



			
				gmartins said:
			
		

> ceg4048 said:
> 
> 
> 
> ...


Well, you know how Klingon warriors try to convince the world that Red this or Red that are the so-called normal colors and so people try all kinds of tricks to get red, all the time ignoring the prime directive, which is to optimize plant health, so they generate more problems than they solve because Red becomes some sort of holy grail. Pigmentation development as a defense mechanism in response to excessive photonic energy is analogous to humans getting sun-tanned on the beach. Who doesn't love a bronzed body?


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## ceg4048 (20 Sep 2011)

*Re: Re: Enough Light?*



			
				niru said:
			
		

> in light of your above statements, would it be accurate to think that plants need an optimal total amount of light above their LCP per day (think of number of light quanta of appropriate frequency, per unit area/amount of photosynthetically active leaf mass, per day)? Then the main question is to appropriately "distribute" these quanta in the intensity (photons/unit time) - versus - light-period (total exposure time). As you mention, the 2 ends of the possibilities are: a single burst of light (will lead to too much damage of cells by heavy bombardment), & uniform light for a given "day"-period ON-time (which is hopefully more than the LCP for THAT frequency). Plants that have higher number of cell-repair medics/mechanisms per vulnerable-to-destruction photocell will then be able to withstand high intensity doses better than others. That could explain the "better" growth & light intensity response of "high light" plants. In nature, the sun's motion in sky (& hence the intensity control per say) dictates this "optimum" growth (or the best light distribution in the intensity-Vs-period as mentioned above) for a given plant.


Well, there really isn't any such thing as optimal amount or optimal frequncies or anything even remotely like that. This is primarily because of the uncanny adaptability of plants. We need to keep in mind that the plants simply have to satisfy at least the minimum amount of energy production required for growth. This is the central theme first raised by the OP. That minimum energy production requirement is strictly a function of how much energy is required to feed every single cell in the plant. So a small plant weighing a few grams only has to satisfy the carbohydrate and oxygen requirement demanded by a few grams of plant cells. If that small plant absorbs more light energy and has sufficient access to nutrients/CO2 then it uses the excess energy to fabricate more plant mass. The higher the excess energy the more quickly the solar energy is converted to mass. This is one of the Grand Illusions people have about plant growth. I'll use a Monty Python reference; "Consider the lilies in the field" They never complain about the amount of sunlight. Lilies grow just as well in England as they do in Spain, even though the latter has much more light. The plants simply adapt to the lighting level and grow as quickly as the total energy allows.

High light plants simply have less efficiency than low light plants. Plants in shade have to make each photon collision count because there are fewer collisions. Plants in shade adjust their energy usage by allocating cell production to more chlorophyll density, for example, which increases the probability of capturing the fewer available photons while plants in bright conditions try to avoid overload by having a lower chlorophyll density and by producing more pigments that reflect/discharge photons. Whaterver energy levels or frequencies are encountered the plant will attempt to regulate. So the effects are fast, medium or slow growth rates and configuration changes to avoid damage or to enhance growth rates.



			
				niru said:
			
		

> Of course one has to be optimal for all frequencies in the light spectra available. So perhaps a warm day-light tube has a different best-growth mode than a bluer light tube. One can then tamper his light periods & intensity differently for different tubes in different manner to achieve a healthy tank. [In nature, for e.g. when sun is closer to horizon its much redder (lower freq) than when its overhead (when relative fraction of high-freq light increases per given amount of sunlight).


Again, no optimization is required because the plants make adjustments based on their needs and on their programmed behavior. The different colors are used to trigger production of certain chemicals, such proteins, enzymes or food. If certain colors are not available in abundance then the plant has the ability to produce certain pigments which actually convert one color to the color it needs to trigger that response.



			
				niru said:
			
		

> Would aquarium plants fare better if such controls are set-in? Moreover, does it make sense of having high-light & low-light plants in the same tank, or that it would explain why some plants do better than others? Are there any works in literature on this?


Well it wouldn't be very interesting to have only one category of plants in tne tank, so it's just a matter of managing the tank. Just because a certain plant is high light it doesn't mean that plant has to have megawattage. This is another fatal misconception that ruins tanks. The difference between high light requirement and low light requirement may be a matter of 10 micromoles or so, not 50. Furthermore, low light plants subjected to higher levels simply require more CO2 to avoid falling off the wagon. So the solution to keeping both is to just not go over the top with light and to provide more CO2 to help those low light planrs cope better with the higher energy levels. Nothing  revolutionary there...



			
				niru said:
			
		

> Are algae also affected by this bombardment for they too have similar light-->chemical energy transition mechanism? If so, then, just as blackouts are used to starve & kill algae (since they cant store food), would high irradiation also work?? Of course plants will suffer as well, but given their regeneration capacities, and food storage possibilities, they might survive?? Particularly if a lightly planted tank is suffering from BGA or mssive BBA invasions, then balckouts followed by irradiation dazzle the heck out of algae? And, more importantly, would it be better than simple blackouts alone?


Nope, the mechnisms are much simpler and algae thrive witn higher radiation because that helps them produce more food more quickly. They don't have to worry about food storage when the lighting is high because food production is maximized. It's only when the light falls off that storage issues arise. That's why blackouts work against them while plants can depend on their stires of food during a few days or more blackout. 



			
				niru said:
			
		

> : Dont the UV-filters try to achieve something similar like this??
> -niru


Ultraviolet damages everthing due to it's high energy and this how green water algae is killed, but that's because the organisms are free floating andd are isolated. If you were to blast the tank itself with high energy UV you'd likely wipe out everything including the plants. That's the trouble with a destructive mindset - you have to destroy the village in order to save it... It's a much better approach to discourage algae by focusing on plant health.

Cheers,


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## niru (21 Sep 2011)

Hi Clive

there is something to think and digest what you have said. Will try during office hours 

The adaptability of plants you mention, wont it take at least a few "generations" for them to do so properly, like a Darwinian scenario?? Are individual plant saplings we plant in the tank soo efficient to manage this within their lifetime (maybe some melting, destruction, but still making their way out in search of a healthy living)?

-niru


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## ceg4048 (21 Sep 2011)

niru said:
			
		

> Hi Clive
> 
> there is something to think and digest what you have said. Will try during office hours


Errr...excuse me, but aren't you supposed to be busy thinking of a way to get us back home through The Star Gate???



			
				niru said:
			
		

> The adaptability of plants you mention, wont it take at least a few "generations" for them to do so properly, like a Darwinian scenario?? Are individual plant saplings we plant in the tank soo efficient to manage this within their lifetime (maybe some melting, destruction, but still making their way out in search of a healthy living)?


No, the Darwinian development has already been completed, maybe billions of years ago. Programmed response to certain environmental changes are already resident in the DNA therefore all the plant needs to do is to sense the environmental changes which then triggers genetic responses, which subsequently trigger the production of proteins and enzymes to address/accomplish the tasks.

Cheers,


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## niru (22 Sep 2011)

ceg4048 said:
			
		

> Errr...excuse me, but aren't you supposed to be busy thinking of a way to get us back home through The Star Gate???
> 
> Cheers,



Well as per the latest info, only a chosen few have been pre-selected based on the ancient Andromedian ritual in the supra-council meeting on the Comet Hale Bopp. Matrix hasnt responded on my receiving frequencies, so guess I am out & cannot be retrieved on the ex-D-day    So I will simply sail with the Star Gate and wait for the Doctor


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