# Lights over 90l tank.



## Henry (9 Apr 2013)

I'm going to set up my biggest tank with pressurised CO2 and EI dosing. Its 15" deep, with the light sitting about 3" above the water's surfave.

Are 2x24w HO T5 going to be enough to grow H. tripartita and other plants with similar demands?


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## ceg4048 (10 Apr 2013)

Hello,
		 Hydrocotyle tripartita does not care about how many watts are in the tank. If you can see the plant through the glass then it probably is enough light. It cares much more about CO2 and nutrients. More light means it will grow faster and will require more nutrition. Less light means it will grow more slowly and therefore nutrition and CO2 levels will be less critical.

Cheers,


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## Henry (10 Apr 2013)

Fair enough, but I'm wanting it to spread across the substrate rather than climb towards the light. I'm wanting to facilitate "high light" growth habits. I'm not a photophile, but I want to have a decent amount of light to bring out pinks in hygrophila etc. Is the proposed lighting going to be enough to do this?


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## NattyAntlers (10 Apr 2013)

Used to run the same light on my Roma 90l and had to battle BBA even with the light up to a 10 inches above the water level .
I managed to clear the problem eventually and not that long ago by increasing the flow by adding a second cannister filter and increasing Co2.
From my experience with Hygrophila you should get what your looking for but make sure the above is covered.


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## ceg4048 (10 Apr 2013)

Yeah, that pretty much sums up high light growth habits. Spreading across the substrate has nothing to do with light intensity and has everything to do with flow and CO2. Pinks in H. polysperma can occur with very little light, so again, this is a misdirection.

Cheers,


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## Henry (10 Apr 2013)

As mentioned above, I will be providing the plants with ample CO2 and nutrients. Flow will be provided by an AquaOne Aquis 1000.

I've never had any Hygrophila species turn red under low light until it has reached the surface. I assumed that light was a factor.


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## ceg4048 (10 Apr 2013)

Maybe CO2 at the surface was another factor.

Cheers,


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## Henry (30 Apr 2013)

So, if I have pressurised CO2, EI dosing, and excellent flow, is this the right amount of light for fast growth?


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## ceg4048 (30 Apr 2013)

Yes! However, easier said than done.

Cheers,


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## Henry (30 Apr 2013)

Very true, but where's the fun in making it easy?


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## zanguli-ya-zamba (30 Apr 2013)

About the plants turning red at the water surface. 
Clive please correct me if I am wrong !!!!
I have read in many thread that for turning certain species in deeper red a small deficiency of KNO3 can induce this. 
Many time in our tank plants are growing green when they are in the middle of the tank and then when it reach the surface the new growth turn red.
That is because at water surface water the light is stronger and accelerate up take. So a small deficiency is created because we are not dosing enough to reach the plant's demand for that amount of light. 

I don't know if you have understand what I have said because of my poor English lol (and I am a bit tired )


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## MirandaB (30 Apr 2013)

I have a Roma 90l with 2x24w T5 HO's sitting about 6 inches from the surface and  it's plenty enough light so far although I find my H.sp Japan still likes to grow up.


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## zanguli-ya-zamba (30 Apr 2013)

Ha and forgot to say I have a 90 L tank, I did a DIY light system with 2x36 w. 
it was too strong, I had to push hard the CO2 to reach the demand. 
Now I have only one tube on at 25 cm from the water surface and it seems to be ok. I also have a bigger margin for errors lol.


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## ceg4048 (1 May 2013)

zanguli-ya-zamba said:


> I have read in many thread that for turning certain species in deeper red a small deficiency of KNO3 can induce this. Many time in our tank plants are growing green when they are in the middle of the tank and then when it reach the surface the new growth turn red. That is because at water surface water the light is stronger and accelerate up take. So a small deficiency is created because we are not dosing enough to reach the plant's demand for that amount of light.


Hi mate,
	 There are lots of reasons for the color change. Plants have lots of different pigments and each pigment has a different function and therefore a different color. There are three main jobs of pigments:
The first job is to absorb the energy of the specific color(s) of light and to pass this energy on for conversion to chemical energy.

The second main job is to protect the plant from radiation poisoning by reflecting away the energy of specific color(s) from the leaf if those colors have too much energy.

The third main job is to change the color of the inbound light and to then reflect that new color on to another set of pigments within the leaf in order to trigger some response in the plant.

Pigments are very complicated molecules and so they are very expensive to manufacture. The plant must analyze the inbound spectral energy, compare the energy to available resources such as nutrients and CO2, take into account it's present state of health and then decide which pigments to produce and how many to build and to allocate.

So there you have a wide variety of conditions that can result in color change. It's not as simple as adding more of this or adding less of that. There is always the equation of survival and reproduction that must be solved.

Chlorophyll is a strongly green pigment as we all know, and this molecule is composed of a high percentage of Nitrogen. The human visual cortex is mostly responsive to green. Therefore, when the chlorophyll content of the leaf is high, then there is a tendency for the green coloration to dominate our perception of the leaf's color. It is entirely possible therefore that under a Nitrogen limitation, which would restrict the population of Chlorophyll, we would perceive less green and other colors. But this condition can happen whether the leaf is at the surface or not.

Nitrogen starvation is one of the reasons we see plant leaves looking yellow. When the chlorophyll density of the leaf is poor, it's color influence is reduced. ANY nutritional deficiency which curtails the production of chlorophyll will result in a color change. When we see Autumn colors on trees for example, this is because the tree pulls the high value chlorophyll away from the leaves for storage, and the remaining pigments, such as Carotene, which are yellow, red or orange, remain in the leaf.

When the leaf is under spectral stress, such as during excessive lighting, then main job number two has to be implemented. The plant analyzes the characteristics of the inbound photons and determines which photons are causing the damage. It then develops pigments in that leaf which reflect as many of those photons as possible. So the pigment choice is very specific to the colors and strengths of the inbound light. It may require several different pigments as well as very high nutrition to manufacture and produce sufficient levels and types of pigments to protect the leaf from destruction. Each leaf will have a different distribution of pigments because their particular location and orientation will be slightly different than another leaf, and the plant will not manufacture more pigments than it needs for each leaf, so that's why the upper leaves will be colored while the lower leaves, which may not be under as much stress, will not color as much.

The manufacture of certain proteins and enzymes, as well as certain behavioral patterns such as flowering, are triggered depending on the inbound wavelength as well as other environmental factors. The plant will then use job number three to capture inbound photons of a certain color and reflect photons in the target color range. Pigments sensitive to that new color will be distributed in specific locations relative to the fluorescing pigments.

So because of these complications, when we see a color change, it's not always obvious WHY it is happening. There are many cases where color changes occur without increasing the light. In a specific case, it may be that increasing the nutrition or CO2 enables the plant to manufacture a certain pigment.

Here is an example case where light was NOT increased, but instead CO2 and nutrients were exaggerated. From this:





To this:




So in that case, even with a super high Nitrogen content, there was no trouble getting color. As this stem reached the surface though the red disappeared, and we might assume that high light stress caused a different set of pigment distribution. Again, that's only an assumption.

Following the progress of this specimen, this is what the stem looked like when it reached just a few centimeters from the surface. So it lost red and was actually more green/yellow under the highest light possible in that tank. So it's not always possible to predict what colors will appear, or when, until we study each species under a variety of conditions that we have total control over.




Here is a totally different scenario. This is nothing special, just a hodgepodge of stems. On the left of the image the light intensity is less than on the right. That's because the end of the bulb is about in the middle of the photo, so the plants on the left are always in shadow, but look at the L. aromatica in the background. The stems on the right stay bright green even though there is more light on the right, while the sister plants on the left, which are in lower light, have more orange color. On the far lower left, those stems have no difficulty turning red. So really it depends on the sum total of all the environmental conditions being faced by the plants, not just on how bright you make the light. That's only part of the story.




Cheers,


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## zanguli-ya-zamba (1 May 2013)

Maaaaaan 
as usual you got the right explanation hahaha. 
What I can tell you is that reading that when you wake up, turn on your brain lol. 
You got the point mate. 
But what I have explain can be one if the reason for certain species like Rotala rotund. red to turn red when they reach surface ? Or I am still in my bed and dreaming looool 
Thanks for the the in depth explanation and for that nice reading. 
I think I have to go back reading Barr report. I stopped reading at Vol II issue 4. 
And I also think I should read the whole report 3 times  to get every think. 
Have a good day 
Cheers


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## ceg4048 (1 May 2013)

Well mate, no you are not dreaming. What you describe is a possible scenario, but I cannot say how likely it is to happen for that reason compared to other reasons. There are so many combinations of things that can occur in every tank.

Yes, you have to read every issue many times for the data to sink in...

Cheers,


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## ceg4048 (2 May 2013)

MirandaB said:


> I have a Roma 90l with 2x24w T5 HO's sitting about 6 inches from the surface and it's plenty enough light so far although I find my H.sp Japan still likes to grow up.


That should be a clue that low light has nothing to do with vertical growth. This issue is related to poor flow and CO2.

Cheers,


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## MirandaB (2 May 2013)

ceg4048 said:


> That should be a clue that low light has nothing to do with vertical growth. This issue is related to poor flow and CO2.


I was thinking that I probably need to put a small pump where that is growing as I didn't think it was getting enough flow there


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## ceg4048 (2 May 2013)

Well, I know that many people report having success using the various incantations of the Koralia powerhead, so you might want to consider finding one the right size for your tank, or, if you can afford it a larger, more powerful filter would be a better aesthetic solution since it would result fewer objects in the tank.

Cheers,


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## MirandaB (2 May 2013)

I'm currently running a Fluval 206 in there but using the duckbill...wondering whether I should switch to using the spraybar.
I am just concerned about getting the balance right for both the plants and the fish,don't want the poor things thinking they're in a washing machine


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