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LED Lighting

hinch said:
ceg4048 said:
More than likely, the OPs problem has nothing to do with light penetration. He/she is most likely having a CO2 penetration problem. Getting more light will only make the problems worse.

Cheers,
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he didn't mention any algae/plant issues though was just a general question. having seen a scaped tall tank on here before though it was very dark at the bottom of the tank compared to the top even when running multple t5's so surely any type of planting is going to require some form of lighting down the bottom
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OK, so now we confirm that the OP was not merely asking a general question. Generally, whenever someone says "I think I need more light", it's because the plants are failing. The reason I jumped to the conclusion in my earlier post is because this happens everyday. The object lesson here is that when someone makes statement like "I think I need more light", we should always ask the question "Why do you think you need more light?" because 99.99% of people think that light grows plants, so they mistakenly assume that if plants are dying then they need more light to save them, which of course, is false.

The problem with tall tanks has absolutely nothing to do with light penetration. The problem with tall tanks is that they do not have enough CO2. We should know this by now. Holes in plants is a CO2 problem. Telling people to get more light penetration when their plants are dying from CO2 deprivation only leads to more destruction and only makes their problems worse. Plants do not really care about light penetration. They care more about CO2 penetration because CO2 grows plants. Lights just makes them use CO2 faster and that's why they grow faster. But id CO2 is not there in sufficient quantities then they cannot grow. The fact that the light is low at the bottom of the tank actually is HELPING. So please, can we stop telling people to add more light before we clarify what their problem is? Adding more light almost NEVER solves peoples problems.

So lets step back to the beginning and see if we can find a better solution.
I find the following statement absolutely incredible.
nachoheeledge said:
...My only plant issues are that a lot tend to die...
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Well, if that's your only problem then we really need to fix that because that one problem is enough for anybody. This is like saying that my only problem with breathing is that I'm unable to inhale.

There are two main paths to a solution;
1. The high tech path, which is complicated and which involves the enrichment of CO2.
A. The CO2 can be enriched by the injection of gas.
B. The CO2 can be enriched by the addition of liquid carbon such as Excel.
C. The CO2 can be enriched by both methods 1.A and 1.B

The easiest of the above methods is to simply add liquid carbon. The cheapest form of liquid carbon is sold by one of our sponsors=> AE Design Aqua Carbon 4000ml
I've given you the link for the 4 liter bottle because it's cheaper in the long run.

The limitation of this method is the long term cost, the possible toxicity to some plants if overused, and the relative lack of efficiency compared to gas injection methods. The advantages are in the ease of use. Simply add a certain amount in the morning, just before lights on and that's it.

The more complicated path is to invest in a CO2 gas injection system. It's more complicated because it requires more planning, additional plumbing, regulator, solenoid, diffusers, bubble counter, dropchecker and so forth. Please go to the Tutorial section of the forum to read more about the gas injection method. The advantage of this method is that you can achieve very high growth rates due to efficiency, however, CO2 is highly toxic to fauna and this obviously is a major disadvantage, so care must be taken and the CO2 concentration levels must always be monitored.

In addition to CO2 enrichment you will need to improve your flow rate and water distribution methods. That internal filter is much too weak to be effective, so CO2 enrichment actually compels you to add even more equipment.

2. The low tech approach.
This method has the advantage of being very simple. All you need to do is to add plants which are tolerant to low CO2 availability. As mentioned by hinch, Vallis is a hardy species and grows almost infinitely tall, which would add an aesthetic appeal to the back of the tall tank. You could also cover some of your ornaments with various types of mosses which are low CO2 tolerant. Ferns are also a good addition and are low CO2 tolerant. Cryptocorynes also are good in a low CO2 tank.

The disadvantages of course are that the growth rates are very slow and you do get some die back as the plants struggle to adapt to the low CO2. The number of species of available plants that are low CO2 tolerant is small.

I would suggest that you add a few of these types of plants and that you start adding liquid carbon, just so that you can see for yourself what the effects are of enriching CO2, however, as I mentioned, CO2 enrichment comes with it's own set of problems starting with flow/distribution, so if you choose to try CO2 enrichment then you might want to think about a stronger filtration solution or the addition of extra circulation pump(s) to push the water down to the bottom of the tank.

Cheers,
 
If as Clive mention's.." Problem's in tall tank's have absolutely nothing to do with light penetration" then PAR values have little meaning?
 
I hardly think you can achieve something nice if you go on the classic planted aquarium route given the tall shape.
I'd strip it and make a paludarium/riparium (google them) 1/3 water and the background filled with plants, use the ADA soil to fill the plants' baskets and gravel/stones for the bottom of the tank. :)

Mike
 
roadmaster said:
If as Clive mention's.." Problem's in tall tank's have absolutely nothing to do with light penetration" then PAR values have little meaning?
Click to expand...
You're playing with words. OK, I'll play. The answer is yes, PAR values have no meaning if CO2 and water availability are at an infinite values. If the PAR at the bottom of a 1 meter tank is low then the required CO2 value is low. If the PAR at the bottom of the tank is high then CO2 must also be high. Therefore PAR only has relevance to us within the context of CO2 and water availability. That's why a plant can grow on land at equatorial latitudes where PAR is at it's highest value on the planet. As long as water is provided, the CO2 of the atmosphere is at sufficient concentration levels that even at a a PAR value of over 2000 micromoles there is very little difficulty.

At the bottom of flooded tank however, the CO2 concentration level (and it's availability) is 10,000 times less than it is in air, therefore, the sustainable level of PAR that should be given with such poor CO2 availability is a hundred times less than that above of the surface of the water. Plants can easily grow with as little as 10-20 micromoles.

The problem with hobbyists is that few have a PAR meter so they GUESS that PAR is too low when in fact it's often too high for the level of CO2 at that depth. CO2 has to find it's way from the surface of the water all the way down to a depth of 1 meter. Oxygen has to find it's way down 1 meter. It is 10,000 times more difficult for these gasses to find their way to the bottom of the tank than it is for photonic radiation to find it's way to the bottom of the tank simply because the light follows the inverse square rule and is has only decreased by 50% of the energy that it had at 50 centimeters down from the bulb, while CO2 may be 300% less than what is available at 50cm due to slow diffusion rates.

In low light the plant produces a high density of chlorophyll per unit area of leaf and are more efficient gatherers of light. They also produce more Rubisco to become more efficient at gathering CO2, but that costs a LOT more energy to produce...energy that they do not have if CO2 availability is low. Additionally, Rubisco is very slow. Each Rubisco molecule can only process less than 10 CO2 molecules per second, so the rate at which a plant can gather CO2 to make the sugar it needs to live on is much slower than the rate at which chlorophyll can process photons, which happens at the speed of electricity.

Therefore, there is a mismatch between the rate at which CO2 can be turned into food compared to the amount of photonic energy that is available to power the reactions that make food. This excess photonic energy destroys the plant tissues.

CO2 is more important because of it's rarity at 1 meter.

Cheers,
 
Let me see if I understand after reading you last post :) I've only had my planted tank going about a week now. So plants will grow under any light as long as that light is not stronger than the concentration of CO2 in the water, if it is the plants die?

And also is there a complete list anywhere on the site of low verses high CO2 plants?

Thanks,
Matt


Sent from my iPhone using Tapatalk
 
The only thing you worry about when injecting co2 into the water is fauna and bacteria in the filter.
The plants will take an unlimited amount of co2 and nutrients.

The key point is lighting, if your lighting is strong, you'll require heavy co2 injection and nutrient load to accommodate the plants accelerated growth. Too little will ensure that the plant melts and algae thrives.

On a low tech tank, with low lighting minimal water changes of say once a month I believe allows co2 saturation to take place and provide for plants in that way. The minimal water changes and water surface movement will prevent co2 gassing off.
 
Thank you Clive, for detailed explanation, Makes perfect sense.
It ain't about how many bulb's you can run on high energy tank's, but more about CO2 available for said lighting,dispersion of CO2. no matter the depth of tank.
Was not playing I assure you, with word's. Just have seen,read,numerous thread's post's, that seemed to place much emphasis on PAR values, and many light fixtures offer four,six,eight ,bulb's.
Just could not seem to understand why more folk's don't use less lighting with CO2 enhanced tank's as opposed to the multiple bulb's if PAR is not as important, or if it would make thing's more manageable.
Still learning :oops:
 
Hi mate,
OK, I'm with you now. Yeah, the emphasis you noted on PAR is due to everyone's fascination with bright lights. I'm the worst offender. The thing is that the plant health equation starts with PAR. Naturally, if the plants receive too little light, then they cannot obtain enough energy to power the chemical reactions that make sugar. Plats need a minimum amount of light to make food in order to grow. I reckon everyone knows that by now. The problem is that most people don't know what PAR value that minimum amount of light is. That minimum amount of light is called the LCP (Light Compensation Point). This is the amount of PAR, regardless of CO2 concentration, that allows the plant to generate exactly the same amount of food that is being eaten by all the cells in it's body. Unfortunately, The Matrix effectively teaches us that the LCP is some huge number because they compare aquatic plants to the hydroponic industry, and those hydroponic people use powerful lighting right? Well, yes, they do, but what folks don't realize, and never think about is that hydroponic plants also have access to infinite CO2 because they are NOT grown in water. Did you realize that if you talk to your house plants frequently they will grow slightly faster? That's because when you exhale, your body is getting rid of CO2 in high concentrations so you are blowing CO2 directly on the plant.

Aquatic plants don't have this luxury, so the only way we can "talk" to them is to blow CO2 into the water, and even so, the CO2 still takes a long time to reach them because of the slow diffusion rates that gasses have in water.

The purpose of light is as thermonuclear power source, but the plant cannot use this energy directly. Quantum energy must be converted to chemical energy, and when that happens, the chemical energy is used to make sugar. The sugar can only be synthesized using water + CO2. The plant eats this sugar and grows because of calories of the sugar. So without CO2 and water to make sugar, this radiation energy being thrown at the plant is not only irrelevant, but it's also dangerous to their tissues. Have you ever experienced sunburning at the beach? Well, that's what happens to the plant constantly under high lighting. However, when the CO2 and water are present in abundance there is fuel that can be made from all that energy. When either one is missing, no fuel can be made and the plant starves to death. If your houseplant is not given water it shrivels right? Even though there is plenty of CO2 carbohydrates cannot be made without water. So the shriveling of the houseplant is mostly due to loss of sugar production as much as it is due to "drying out". In an aquatic environment, where water is in abundance, CO2 is missing and so those plants shrivel due to starvation. Shriveling houseplants and melting aquatic plants are actually dying for exactly the same reason - starvation due to the inability to produce sugar because of a missing ingredient.

This is why I say that the PAR is irrelevant, because it has no meaning if the sugar that it is supposed to help produce cannot be produced because of a lack of the basic ingredient. So we really need to change our perception about the how and why of plant growth if we are to succeed. Think about how many plants grow in the Sahara dessert where there is plenty of light and plenty of CO2 but has no water and compare that with the amount of plants in the UK, which hardly has any light but has plenty of CO2 and water. How can Oak trees get that big under such gray skies? If we apply this thinking to our tanks we'll realize that we do not need to focus "do we have enough light?" but rather, "do we have enough CO2?" because that's the missing ingredient for sugar production.

Cheers,
 
ceg4048 said:
It is 10,000 times more difficult for these gasses to find their way to the bottom of the tank than it is for photonic radiation to find it's way to the bottom of the tank simply because the light follows the inverse square rule and is has only decreased by 50% of the energy that it had at 50 centimeters down from the bulb, while CO2 may be 300% less than what is available at 50cm due to slow diffusion rates.
Click to expand...

I have learnt so much reading this forum and have to say thanks Clive - your explanations are awesome. But I would just like to explore the inverse square law thing.... If PAR were following the inverse square law, I think it would be 25% at twice the distance?

BUT in a tank, especially a deep one like this I don't think the inverse square law applies. The light that enters the water will mostly stay there until it hits something. It will be contained within the tank due to reflections off the water and glass interfaces with air. If there is much light fall off due to distance I think it will be mostly due to absorbtion in the water and any impurities there might be.

Unfortunately, or not depending on you point of view, this makes this particular situation with light vs CO2 even worse (as there will be more light than you would think).

I don't think this will apply to shallow tanks to as great an extent, just deep ones.

Regards, Mike.
 
Hi Mike, yes you are right about the percentages, sorry, I think I had a bit shift or something... The inverse square rule only "roughly" applies in the tank but it's modified as you mentioned because of reflections and so forth. You do get reflections from the underneath of the surface of the water as well as reflections from other parts of the tank, glass, substrate and so forth. And yes, you are correct, the turbidity of the water is a factor which would reduce the penetration. The water absorption is not very much at only 1 meter. When biologists measure the water absorption in bodies of water they talk about standard absorption values like "Secchi depth" and so forth but our tanks aren't deep enough for these parameters to be relevant. As you say it means that there is more light at the bottom of that tank than we would imagine. I saw a chart produced by someone on the Barr Report who had done the measurements in his tank and came up with a curve that looked kind of logarithmic and not quite a second order curve. In any case, inverse square was close enough for the point I was trying to make but I goofed on the numbers...sorry... :crazy:

Cheers,
 
OK Clive, no worries - keeps everyone on their toes :)

It sounds like a more "interesting" problem than I thought. I'll have a look for that chart when I get time.

Regards, Mike.
 
Alot of members on here use shower caddies around their tanks for growth outside the tank but you could use some on the sides and experiment with how deep down they can go and still be healthy. You could also try some redmoore or similar pointing down the way sort of mangrove style and again have some plants tied on to the wood higher up.
 
Bit of a debate going on in this thread. I've successfully used LED GU10's before, they're pretty cheap, readily available and easy to fit. Here's my 3 part series of using them on my tank. Good luck finding an answer, it is a strange tank though, how do you find cleaning it and stuff?
 
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