# What PAR numbers for each light level



## sudhirr (Apr 12, 2019)

Dennis Wong from advanced planted tank site has an article that calls this out. 30 is low, 50 is med and 90 is high. 


https://www.advancedplantedtank.com/blogs/light-3pillars/par_for_planted_tank


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## EdWiser (Jul 14, 2015)

Well I test lights for my aquarium club. And many LED’s that are 300 par 
I would consider 50 par a really low light led.


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## Deanna (Feb 15, 2017)

I look at this way:

Low CO2 (<20ppm) substrate readings
Low Light: 15-30 PAR
Med Light: 30-50 PAR (no more for low CO2 setups)

High CO2 (30-40ppm) substrate readings
Low Light: 30-50 PAR
Med Light: 50-80 PAR
High Light: >80PAR


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## Jah410 (Feb 11, 2019)

Deanna said:


> I look at this way:
> 
> Low CO2 (<20ppm) substrate readings
> Low Light: 15-30 PAR
> ...


Are you considering these all as substrate readings? 
...


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## Deanna (Feb 15, 2017)

Jah410 said:


> Are you considering these all as substrate readings?
> ...


Yes


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## Asteroid (Jul 26, 2018)

Jah410 said:


> One thing that is bugging me is determining how strong a light really is.
> 
> What PAR levels do you guys find correspond to low, medium, and high light? High level being able to grow high light plants and also get the full coloration to show (Reds, oranges, etc.).
> 
> At what point does CO2 become necessary/actually beneficial.


From my experience co2 is beneficial at all light levels. There is a shortage of it regardless of light. Some plants that won't grow in low-tech, will grow in a Walstad-type setup because of the add'l co2 generated from the dirt.


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## exv152 (Jun 8, 2009)

By the way, dirt does not produce co2 (carbon dioxide). Plants will use carbon from multiple sources, including the carbon in the dirt and the mulm of decaying plant matter. The plants will also use the carbon in the carbonate hardness, which is why KH can sometimes diminish in a high tech tank. But CO2 is beneficial at all light levels. Plants cannot photosynthesize without light, nutrients and *a carbon source*. The most common source of carbon in low tech tanks is carbonic acid H2CO3. But some slow growers do better with this type of carbon (like anubias, crypts, mosses, ferns etc), while other plants will simply not survive without the addition of co2. But all plants need a source of carbon. That's why adding co2 regardless of your light level is never a waste.


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## Asteroid (Jul 26, 2018)

exv152 said:


> By the way, dirt does not produce co2 (carbon dioxide). .


So using the correct soil, are you saying that co2 is not produced from decomposition of organic matter? Are you saying the co2 levels in a dirt/soil tank don't have the ability to be higher than one with an inert substrate and no co2 injection?


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## exv152 (Jun 8, 2009)

Asteroid said:


> So using the correct soil, are you saying that co2 is not produced from decomposition of organic matter? Are you saying the co2 levels in a dirt/soil tank don't have the ability to be higher than one with an inert substrate and no co2 injection?


There is very limited CO2 in submerged dirt. That is why aquarium plants have developed a mechanism to tap other carbon sources. Two major sources of carbon are 1) the extraction of bicarbonate and 2) carbonic acid from decaying plant matter. Carbon and CO2 are not the same thing.


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## Asteroid (Jul 26, 2018)

exv152 said:


> There is *very limited CO2* in submerged dirt. That is why aquarium plants have developed a mechanism to tap other carbon sources. Two major sources of carbon are 1) the extraction of bicarbonate and 2) carbonic acid from decaying plant matter. Carbon and CO2 are not the same thing.


You could throw all the science at it that you want, but it's FACT that tanks with the correct soil have increased co2 available to plants above and beyond what they will have in a tank with an inert base and no injection. This has been studied by Walstad as well as plenty of hobbyist tanks. I have no desire to go back and forth on the exact reason you think it's not so. It really can't be refuted when it happens in thousands of tanks. Not sure what you mean by very limited but tanks can generate upwards of 8 to 10 ppm of co2, which can make the difference between some plants growing or not.


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## exv152 (Jun 8, 2009)

Sorry, you’re fundamentally misunderstanding why dirted tanks do better because you’re confusing carbon with co2. They are not the same thing.


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## Asteroid (Jul 26, 2018)

exv152 said:


> Sorry, you’re fundamentally misunderstanding why dirted tanks do better because you’re confusing carbon with co2. They are not the same thing.


I think one is a solid and one is a gas. I'm just not 100% sure which one. I'm gonna guess and say the co2 is the gas. >

So if your saying I'm misunderstanding then your also saying D.Walstad is misunderstanding and her book is wrong. As well as well as anyone else achieving higher levels of co2 in a soil-based tank?


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## jeffkrol (Jun 5, 2013)

Worth reading 
https://blogs.ei.columbia.edu/2018/02/21/can-soil-help-combat-climate-change/

Though how it pertains to waterlogged souls is ??


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## exv152 (Jun 8, 2009)

Asteroid said:


> I think one is a solid and one is a gas. I'm just not 100% sure which one. I'm gonna guess and say the co2 is the gas. >
> So if your saying I'm misunderstanding then your also saying D.Walstad is misunderstanding and her book is wrong. As well as well as anyone else achieving higher levels of co2 in a soil-based tank?


Again, you’re deeply missing the point. I’m in agreement with Walstad. You’re making a misleading statement when you claim dirt creates or contain co2 in a submerged aquatic environment. Not even Walstad is making that claim. Dirt does not create/contain co2, but it contains a very valuable supply of carbon. Carbon (c) is not carbon dioxide (CO2). Plants only use the C portion of CO2. But I see that you’ve only been on the forum for 2 years and you already have more than 2200 posts, which says a lot.


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## jeffkrol (Jun 5, 2013)

Didn't read the link huh.




> As the plants respire, they return some carbon dioxide to the atmosphere and exude some carbon as a sugary substance through their roots. This secretion feeds the microbes (bacteria, fungi, protozoa and nematodes) that live underground. When the plants die, soil microbes break down their carbon compounds and use them for metabolism and growth, respiring some back to the atmosphere.
> 
> Because microbial decomposition releases carbon dioxide, the soil can store more carbon when it is protected from microbial activity. One key way that happens is through the formation of soil aggregates. This occurs when tiny particles of soil clump together, sheltering carbon particles inside them. Mycorrhizal fungi, which produce sticky compounds that facilitate soil aggregation, are able to transfer 15 percent more carbon into the soil than other microbes. Soils with high clay content are also able to form chemical bonds that protect carbon from microbes. These aggregates give soil its structure, which is essential for healthy plant growth.
> 
> Some carbon, made up mainly of plant residue and the carbon exuded by plant roots, remains in soil only for a few days to a few years. Microbes can easily digest this “fast pool” of carbon, so it emits a great deal of carbon dioxide. The “slow pool,” where carbon can remain for years to decades, is composed of processed plant material, microbial residue from the fast pool and carbon molecules that are protected from microbes. A third “stable pool,” comprised of humus—decomposed organic material—and soil carbon that is well protected from microbes, is found below one meter deep and can retain carbon for centuries to millennia.


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## gjcarew (Dec 26, 2018)

Carbon and CO2 are often used interchangeably in climate literature, which is where there might be confusion. In waterways, organic matter (dead leaves, wood, dead plankton, dead fish) falls to the bottom of the waterway, where it decomposed largely by aerobic bacteria. Aerobic respiration creates CO2 as a byproduct. So if the dirt contains organic matter, then the decomposition of that organic matter will in fact create CO2 in the water column. I'm sure Walstad is aware of this, it's freshman-level biology.

When you put dirt in an aquarium, it's a source of organic matter (containing carbon) that through decomposition, produces CO2. So you're right that there is not sequestered CO2 in the dirt when it goes in to the aquarium, but wrong in that dirt does produce CO2 through bacterial aerobic respiration.

https://environment.yale.edu/envy/stories/streams-and-rivers-breathing-carbon-dioxide#gsc.tab=0
https://www.frontiersin.org/articles/10.3389/fmars.2017.00076/full


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## Asteroid (Jul 26, 2018)

exv152 said:


> Again, you’re deeply missing the point. I’m in agreement with Walstad. You’re making a misleading statement when you claim dirt creates or contain co2 in a submerged aquatic environment. Not even Walstad is making that claim. Dirt does not create/contain co2, but it contains a very valuable supply of carbon. Carbon (c) is not carbon dioxide (CO2). Plants only use the C portion of CO2. But I see that you’ve onlya been on the forum for 2 years and you already have more than 2200 posts, which says a lot.


Well if your with Walstad, she claims that *co2 ppm* raises in her setups with soil from decomposition of organic matter in the soil. How does co2 increase if your saying there is no increase? What does my post count have to do with anything? Is there a problem having 2200 post in 2 years? i'm simply making a point there is more co2 available with a soil substrate then with an inert one. We are talking aquariums, understand the context your dealing in and don't just state science.


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## Bunsen Honeydew (Feb 21, 2017)

Are we trying to delineate between dissolved CO2 in water and carbonic acid? That's an interesting assertion.

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## exv152 (Jun 8, 2009)

Don't take my word for it, research has been done on this by the university of Arizona, co2 is very limited in the aquatic soil environment so plants adapt to getting carbon from other sources. See the quote and link below. I also recall reading an article in the May/June 2012 Amazonas magazine on the subject.

_"Some have partial terrestrial forms, such as floating leaves or above water growth, which allows them to use carbon dioxide from the atmosphere. But for plants that live completely submerged in water, CO2 is limited and many of these plants have developed a mechanism to tap into other carbon sources. In this case, they extract it from bicarbonate -- a naturally occurring mineral that comes from the weathering of soils and rocks and the runoff reaches the plants."_

https://www.sciencedaily.com/releases/2019/11/191114141302.htm


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## jeffkrol (Jun 5, 2013)

Asteroid said:


> I'm simply making a point there is more co2 available with a soil substrate then with an inert one. We are talking aquariums, understand the context your dealing in and don't just state science.



Actually if I understand this right.. that is really a "it depends"..
High CEC soils may bind carbon (carbon in the form or other than CO2) whereas open mulm filled inert soils do not as much.






> Because microbial decomposition releases carbon dioxide, the soil can store more carbon when it is protected from microbial activity. One key way that happens is through the formation of soil aggregates. This occurs when tiny particles of soil clump together, sheltering carbon particles inside them. Mycorrhizal fungi, which produce sticky compounds that facilitate soil aggregation, are able to transfer 15 percent more carbon into the soil than other microbes. Soils with high clay content are also able to form chemical bonds that protect carbon from microbes. These aggregates give soil its structure, which is essential for healthy plant growth.



All aquarium substrates are probably chock full of microbes and water molds (assumption) so any "carbon" lying around in it has a chance of decomposition to CO2.
Soil substrates probably are at an advantage because it is already richer in carbon to begin with.


Substrates that are high CEC clays are probably the lowest CO2 producers due to the above.


Being underwater matters little unless O2 is limited.



> Not only does healthy wetland vegetation have the potential to take up large amounts of CO2 through photosynthesis, but also flooded soils have low oxygen levels which reduce rates of decomposition to promote retention of soil carbon.


https://www.usgs.gov/centers/wetlan...ce_center_objects=0#qt-science_center_objects


Bump:


exv152 said:


> Don't take my word for it, research has been done on this by the university of Arizona, co2 is very limited in the aquatic soil environment so plants adapt to getting carbon from other sources. See the quote and link. I also recall reading an article in the May/June 2012 Amazonas magazine on the subject.
> 
> _"Some have partial terrestrial forms, such as floating leaves or above water growth, which allows them to use carbon dioxide from the atmosphere. But for plants that live completely submerged in water, CO2 is limited and many of these plants have developed a mechanism to tap into other carbon sources. In this case, they extract it from bicarbonate -- a naturally occurring mineral that comes from the weathering of soils and rocks and the runoff reaches the plants."_
> 
> https://www.sciencedaily.com/releases/2019/11/191114141302.htm



Actually most of that seems to imply "limited as compared to atmospheric CO2" which goes w/out saying really.


In aquatic systems you are referring more to "limited" vs more limited"
Any microbiological degradation will STILL lead to CO2 limitations vs atm no matter how muc (assumption).
But does it make the tank "less limited" than say a bare bottom?
I think not. 

Personally think it makes the tank "less limited".. 

Many aquatic plants do fix CO2 in the Malic acid cycle but it is energy intensive..
https://pubs.er.usgs.gov/publication/70021106

AS you can't exactly compare crops to aquariums, neither can you compare natural aquatic systems to aquariums.
In a sense it's just a matter of degrees though..

There is no aquatic system that can match atm.. So all are limited..


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## Asteroid (Jul 26, 2018)

gjcarew said:


> ... So if the dirt contains organic matter, then the decomposition of that organic matter will in fact create CO2 in the water column. I'm sure Walstad is aware of this, it's freshman-level biology.
> 
> . So you're right that there is not sequestered CO2 in the dirt when it goes in to the aquarium, but wrong in that dirt does produce CO2 through bacterial aerobic respiration.
> [


That's all I was saying from the getgo. I mentioned decomposition of organic matter in pretty much every post. I didn't say dirt itself inherently has co2. 

At the end of the day there is more co2 in soil-based tanks from organic decomposition in the soil. Within the context most here know what am talking about. Once someone mentions post counts and starts getting personal you know there's an issue and no sense discussing anymore.


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## gjcarew (Dec 26, 2018)

Bunsen Honeydew said:


> Are we trying to delineate between dissolved CO2 in water and carbonic acid? That's an interesting assertion.
> 
> Sent from my Pixel 3 XL using Tapatalk


Water catalyzes a reaction that decomposes H2CO3 into H20 + CO2. So any carbonic acid in solution will eventually become CO2.

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## Bunsen Honeydew (Feb 21, 2017)

gjcarew said:


> Water catalyzes a reaction that decomposes H2CO3 into H20 + CO2. So any carbonic acid in solution will eventually become CO2.
> 
> Sent from my Pixel 3 using Tapatalk


Water isn't a catalyst, it is part of the equilibrium.

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## Econde (Oct 13, 2015)

You guys science too hard. I was just trying to read about par haha. Interesting nonetheless!


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## gjcarew (Dec 26, 2018)

Bunsen Honeydew said:


> Water isn't a catalyst, it is part of the equilibrium.
> 
> Sent from my Pixel 3 XL using Tapatalk


Pretty sure it's both? The reaction is catalyzed by water and also creates water as a product

You're the guy with the beaker profile though!

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## Bunsen Honeydew (Feb 21, 2017)

gjcarew said:


> Pretty sure it's both? The reaction is catalyzed by water and also creates water as a product
> 
> You're the guy with the beaker profile though!
> 
> Sent from my Pixel 3 using Tapatalk


It can't be both. A catalyst isn't consumed in a reaction and lowers the activation energy of the reaction. 

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## gjcarew (Dec 26, 2018)

Bunsen Honeydew said:


> It can't be both. A catalyst isn't consumed in a reaction and lowers the activation energy of the reaction.
> 
> Sent from my Pixel 3 XL using Tapatalk


Yeah, more sidebars!

I'm not going to pretend I understood this paper in great technical detail, but this is what I was looking at:

"Dry carbonic acid has recently been shown to be kinetically stable even at room temperature. Addition of water molecules reduces this stability significantly, and the decomposition (H2CO3 + nH2O --> (n+1)H2O + CO2) is extremely accelerated for n = 1, 2, 3."

It seems that the H2O is not consumed and speeds the reaction. Does that not make it a catalyst? 


Towards the Experimental Decomposition Rate of Carbonic Acid (H2CO3) in Aqueous Solution.
January 2002. Chemistry 8(1):66-73.
Https://www.researchgate.net/public...text=Dry carbonic acid has recently,= 1, 2, 3.

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## Bunsen Honeydew (Feb 21, 2017)

gjcarew said:


> Yeah, more sidebars!
> 
> I'm not going to pretend I understood this paper in great technical detail, but this is what I was looking at:
> 
> ...


Well, ignoring that this is far out of the context of aqueous carbonic acid in an aquarium that we were talking about, we can talk about dry carbonic acid. The key to what you quoted is that it is kinetically stable, not thermodynamically stable. Since the decomposition is through a polar mechanism, it would be enhanced significantly by any polar solvent or medium. Since it is producing water, the process would become autocatalytic with a small amount of water, but given that water is a product of the reaction (which is an equilibrium), I wouldn't want to be the one trying to defend that it is a catalyst. I'd say that such an assertion is at least reasonable in a very constricted set of conditions. I don't think that exceptions disprove rules, and this context is very far away from what happens in an aquarium.

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## gjcarew (Dec 26, 2018)

Fascinating, you learn something new every day. Today that was the difference between kinetic and thermodynamic stability


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## Bunsen Honeydew (Feb 21, 2017)

gjcarew said:


> Fascinating, you learn something new every day. Today that was the difference between kinetic and thermodynamic stability


Thermodynamic stability means that a compound is stable because it is low energy, whereas kinetic stability refers to a compound that is higher energy, but converts to the lower energy compound (or compounds) slowly for various reasons.

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## Deanna (Feb 15, 2017)

jeffkrol said:


> Didn't read the link huh.


I did (another good read)! I found the comment on the Mycorrhizal fungi particularly interesting. I've added this to my lawn every year, for many years, for a multitude of benefits, not least being that they enhance the uptake ability of roots for many nutrients.

Now, I'm wondering if they might benefit my tank, even with my inert substrate, and they might be better with soil-based substrates. Does anyone see any harm in using these in a tank? My source is here: https://smile.amazon.com/gp/product/B077CS6B18/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1


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## jeffkrol (Jun 5, 2013)

Deanna said:


> I did (another good read)! I found the comment on the Mycorrhizal fungi particularly interesting. I've added this to my lawn every year, for many years, for a multitude of benefits, not least being that they enhance the uptake ability of roots for many nutrients.
> 
> Now, I'm wondering if they might benefit my tank, even with my inert substrate, and they might be better with soil-based substrates. Does anyone see any harm in using these in a tank? My source is here: https://smile.amazon.com/gp/product/B077CS6B18/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1



There is precedent for mycorrhyzal fungi in aquatic soils..


> Free-floating roots growing in water close to the banks were non-mycorrhizal but were mycorrhizal in the bottom-rooting state.


though I'm not sure that considers 100% (time wise) immersion.


Getting the correct species may be an issue.


I don't have free access but it gives plenty of hints. 

https://link.springer.com/chapter/10.1007/978-81-322-1865-4_8


> It is, however, hard to accept these generalised perceptions, partly because only a few studies have been hitherto carried out on mycorrhizal symbioses of aquatic plants, thereby leaving huge information gaps and paucity of quantitative data in this area of research.


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## Jeff5614 (Dec 29, 2005)

Asteroid said:


> What does my post count have to do with anything? Is there a problem having 2200 post in 2 years? .


I think he was complimenting how much you've contributed to the forum .


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