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150 ppm co2?

aquanoobie

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Plant will use as much CO2 there is available and as light requires/induces.
Research demonstrated that submerged plants do not need more than 30 ppm CO2 even under direct sunlight. Also, do you know anyone claiming the necessity of having 100 ppm of CO2 or facing issues related to too low CO2 at 30 ppm?
Emersed plants are exposed to ambient 400ppm ++ of CO2 and they use it all-right. In greenhouse CO2 is injected to around 1000ppm sometimes more.
Yes, that's how emersed plants work. In fact, terrestrial plants worldwide are starving for more carbon because of critically low atmospheric CO2 levels. We have ~ 400 ppm now thanks to burning fossil fuels for the last 120 years. It was as low as 300 ppm 120 years ago and it was like this for thousands of years, dropping down to critical level for plants to trive. The best time plants had it was when CO2 level in atmosphere was up to 8 000 ppm, 20 x more than today, it was millions of years ago. That's when ferns grew as large as trees. CO2 molecule is one of the most important molecules keeping this planet alive, CO2 is a molecule of life.
I disagree with this. As a starter because of the caveat your mentioned, but most importantly because depending where your place the DC you will have very different readings. So which DC is lying now?
Is pH probe positioning irrelevant?
DCs don't technically tell you what the actual overall CO2 concentration in the water column is, but more the concentration of CO2 at that specific spot.
Is pH probe any different? Does your pH probe technically read actual CO2 ppm? No, it doesn't neither.
It's best to use the PH drop method. So -1PH =~ 30ppm.
This is the least accurate method. The pH drop indicates how many times more CO2 is in the water sample in relationship to equilibrium with atmosphere. That's it, this is where it ends.

For the simple reason not knowing the atmospheric CO2 level at the testing site this process is not telling us what we want. Do you know what CO2 level is in your room air? I bet you don't. It can be anything between 400 and 2 500 ppm. The 400 is the average outside and the 2 500 has been tested in homes and malls. The 400 ppm CO2 infusion in water gives 0.5 ppm CO2 and the 2 500 gives significantly more. Now multiply this by your pH drop rate. In reality it can be anything. How accurate is it?
 

Hanuman

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Research demonstrated that submerged plants do not need more than 30 ppm CO2 even under direct sunlight. Also, do you know anyone claiming the necessity of having 100 ppm of CO2 or facing issues related to too low CO2 at 30 ppm?
Please share such research. Always willing to learn more. Regardless, it's not about someone having the "necessity of" but rather if a plant can. You can grow plants at 30ppm, 20ppm, 10ppm heck even lower... that's exactly what happens in low tech tanks.
Is pH probe positioning irrelevant?
Technically no, but the PH of the water column of a tank tends to be more homogenous, so the reading of a PH probe will give you a better overall view of your tank compared to a DC which on top of this lags 2 to 3 hours.
Is pH probe any different? Does your pH probe technically read actual CO2 ppm? No, it doesn't neither.
See comment above.
This is the least accurate method. The pH drop indicates how many times more CO2 is in the water sample in relationship to equilibrium with atmosphere. That's it, this is where it ends.

For the simple reason not knowing the atmospheric CO2 level at the testing site this process is not telling us what we want. Do you know what CO2 level is in your room air? I bet you don't. It can be anything between 400 and 2 500 ppm. The 400 is the average outside and the 2 500 has been tested in homes and malls. The 400 ppm CO2 infusion in water gives 0.5 ppm CO2 and the 2 500 gives significantly more. Now multiply this by your pH drop rate. In reality it can be anything. How accurate is it?
Well unless you live in a factory, a mall or a cave, your CO2 level will be closer to 400ppm than the higher range. And to answer that question, yes I do have a CO2 detector which currently reads 458ppm :) - In the morning it read ~500 ppm give or take 5%. You're never too prudent when having a CO2 cylinder at home!
The pH drop indicates how many times more CO2 is in the water sample in relationship to equilibrium with atmosphere. That's it, this is where it ends.
Please elaborate on this. As much I know that a PH probe does not measure per say CO2 levels, it provides in my option a better approximation of what is in your tank. The -1PH ~ 30ppm is obviously an approximation, not a hard number. We all know that and live with that. I don't even understand what the equilibrium with atmospheric CO2 has to do here. We are forcefully dissolving CO2 at a much higher rate in a tank which is hardly the same thing as having 400-2500pm lingering in the air slowly dissolving in water. My PH would barely budge if I didn't inject any CO2.

In my opinion reading a DC's color is by far less accurate. But that's just me.
 

MichaelJ

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Interesting research article, that shows big seasonal variations of dissolved CO2 in the Amazon river basin.

Richey, J.E. and others. 2002. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2, Nature 416, 617-620

Perhaps someone can help and translate the partial pressure of CO2 in the graph into the for us more common CO2 ppm?
I think it's something like vapor pressure / partial pressure x 10^6 = ppm. Probably wrong... but looping in @dw1305 as Darrel probably knows this.

Good post @Yugang . Will have to read this article.

Cheers,
Michael
 
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aquanoobie

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Well unless you live in a factory, a mall or a cave, your CO2 level will be closer to 400ppm than the higher range. And to answer that question, yes I do have a CO2 detector which currently reads 458ppm :) - In the morning it read ~500 ppm give or take 5%.
That's beatiful, I need one too!
Room CO2 levels vary a lot depending on the house structure and season. How the house is sealed and air conditioning or heating running. There are houses where CO2 was tested in the 2 500 ppm range.
Please elaborate on this. As much I know that a PH probe does not measure per say CO2 levels, it provides in my option a better approximation of what is in your tank. The -1PH ~ 30ppm is obviously an approximation, not a hard number. We all know that and live with that. I don't even understand what the equilibrium with atmospheric CO2 has to do here.
The whole idea of using pH probe as a proxy to get CO2 levels is based on differential pH between gassed and degassed water. And the only thing we know is that 1 pH => 10 x more CO2. But the problem is the degassed water doesn't have to be the same at different locations and timings. So let me ask you, where is the 1 pH drop getting the 30 ppm of CO2?

The princip doesn't have a solid starting point, no solid base. Most of us don't know the room air CO2 level so we cannot know what degassed CO2 ppm is. And even if we can test air CO2, we still don't know what it's equilibrium be. Then we go for 1 pH drop and we know we have 10 x more CO2 ppm than is in the degassed sample. But what is it? Is it 0.5, 5 or 10, we don't know. So how can we say 1 pH drop => 30 ppm, based on what?
 

Hanuman

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The whole idea of using pH probe as a proxy to get CO2 levels is based on differential pH between gassed and degassed water. And the only thing we know is that 1 pH => 10 x more CO2. But the problem is the degassed water doesn't have to be the same at different locations and timings. So let me ask you, where is the 1 pH drop getting the 30 ppm of CO2?

The princip doesn't have a solid starting point, no solid base. Most of us don't know the room air CO2 level so we cannot know what degassed CO2 ppm is. And even if we can test air CO2, we still don't know what it's equilibrium be. Then we go for 1 pH drop and we know we have 10 x more CO2 ppm than is in the degassed sample. But what is it? Is it 0.5, 5 or 10, we don't know. So how can we say 1 pH drop => 30 ppm, based on what?
Agreed. Past observations and testing state that degassed water is somewhere arounf 3 to 4ppm so that's where the base line starts and the 1 PH drop equating to ~ 30ppm of CO2 is picked up. Your 400-2500ppm range is irrelevant in my opinion. We are not doing lab experimentation that require lots of accuracy. We are only interested in a way to dose CO2 to the point where it is not harmful to fish. The 30ppm could be 20ppm or 45ppm for all I care. What's more important is that everyone in the tank is healthy and plants grow and no algae proliferation is observed.

To me this is still better than using a simple DC for reasons I have already stated above.

Here are some link for those interested, which I assume you are already aware of:
 

GreggZ

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Research demonstrated that submerged plants do not need more than 30 ppm CO2 even under direct sunlight. Also, do you know anyone claiming the necessity of having 100 ppm of CO2 or facing issues related to too low CO2 at 30 ppm?
Curious what research is this?

And yes I know plenty of people who's tank would be better if they optimized CO2 and had a higher concentration.

One issue is that many think their CO2 concentration is 30 ppm, but in reality they have no idea. It could more like 10 ppm. The charts are useless. There are more elements at play than just CO2 in our tanks.

And all of the theoretical nonsense aside for someone who is interested in having a great tank the pH drop method is easily the best method we have. If you know how to do it correctly it's our best available tool to dial in CO2 and keep it steady. That is unless you have access to very expensive test equipment.

IMO too many times folks get lost in the minutia and lose focus on what's important. Learn how to properly fully degas a sample, use a good calibrated probe, understand the dKH/pH/CO2 relationship, then take that knowledge to keep a steady pH drop and your odds of success will greatly increase.

So how can we say 1 pH drop => 30 ppm, based on what?
Now this I agree with. My pH drop is 1.4. What is my actual CO2 level? Who knows. The charts would say well over a hundred. Is it really? Not likely.

But matters little in the scheme of things. You want to dial in whatever level makes the plants the most happy and keeps livestock comfortable. Whatever that ppm is it pays to keep it steady at that level, and pH drop is the best tool to do so. Massive swings in CO2 are just as rough on some plants as massive swings in nutrients so it pays to get it right.
 

Gorillastomp

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Now this I agree with. My pH drop is 1.4. What is my actual CO2 level? Who knows. The charts would say well over a hundred. Is it really? Not likely.
I usually keep my ph drop around that 1.3 1.4 marks, but lately i decided to test out what it could do if i push it further more so i have increased it slowly over weeks, months to about 1.8 drop. I haven't seen improvement what so ever in growth. Could be that i didn't not have enough light to drive it or something.
 

Wookii

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I'll stick my hand up and be the lonely voice in favour of drop checkers.

With experience a quick glance at my drop checker tells me straight away if I'm hitting the right CO2 levels for my tank. It tells me visually every day if increasing plant mass, or reduced/increase surface agitation has altered the CO2 levels. It even alerts me when my CO2 bottle runs out if I haven't checked the gauges in a while. It also allows me to test measure any point in the tank for distribution issues.

Whilst measuring the pH drop is for sure a good method, for setting initial CO2, and gives an instant reading rather than the drop checkers time delay, it's still fraught with issues. Most aquarists don't stump up for a pH meter with wired probes, and are therefore limited to measuring pH with a integrated hand held meter that can only measure in the top 75mm of water. In my experience with a good quality and accurate pH probe, pH can vary around the tank significantly, in line with CO2 distribution, so is caught with similar location issues to the drop checker in that respect. It's also very labour intensive to take a manual pH profile if you don't have a more expensive data logging probe.

For me setting up a new tank is also easy with the drop checker - I start with slightly over-egging the input rate to get a colour verging on yellow, and then back it off gradually until I hit the right level. I can usually get to the right point within a couple of days, which is far easier and less labour intensive than running consecutive manual pH profiles (even though my probe is a data logging type).

Don't get me wrong, I think the committed aquarist should both tools in their arsenal, but I find with experience I rely on the drop checker much more.
 

GreggZ

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I usually keep my ph drop around that 1.3 1.4 marks, but lately i decided to test out what it could do if i push it further more so i have increased it slowly over weeks, months to about 1.8 drop. I haven't seen improvement what so ever in growth. Could be that i didn't not have enough light to drive it or something.
Many I know have tested this theory over the years and have found it subject to the law of diminishing returns. Once you get to to a certain level plants have all they can possibly uptake and the extra is wasted.

I'll stick my hand up and be the lonely voice in favour of drop checkers.
It all depends on how precise you want to be and your level of ambition. Keep in mind a drop checker is nothing more than a liquid pH test.

I have tested liquid pH tests against good quality calibrated probes and they can be off quite a bit. I adjust my pH drop up/down in 0.05 increments which would be impossible with a drop checker.

But in the scheme of things if you just want "good" CO2 a drop checker will work just fine. If you really want to optimize CO2 a calibrated good quality probe is best. Of the great tanks that I follow I can't think of one that uses a drop checker, but then again their ambition is greater than the average tank.
 

GreggZ

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I'm also on board with the drop checker. Totally idiot-proof and you just look at it to see where you are. People that think they can meaningfully optimise CO2 by measuring pH in 0.05 unit increments are fooling themselves, but if they enjoy doing it that also has value. ;)
LOL I do enjoy the process.

And I did mention tuning in 0.05 increments. Let me explain that.

Let's say my current drop is to 5.00 pH. To fine tune I start by dropping to 4.95. Then observe plants and fish for a few days. Then down to 4.90 and do the same. And then again until I hit the point where plants are pearling and happy and fish show no signs of discomfort.

You may think there is no difference if CO2 is optimized, but in my experience it's easily the best thing most folks could do to increase their success in the hobby. Playing whack-a-mole ferts rarely works, but fine tuning CO2 brings immediate results. But again all depends on one's ambitions in the hobby.
 

aquanoobie

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In fact, terrestrial plants worldwide are starving for more carbon because of critically low atmospheric CO2 levels. We have ~ 400 ppm now thanks to burning fossil fuels for the last 120 years. It was as low as 300 ppm 120 years ago and it was like this for thousands of years, dropping down to critical level for plants to trive. The best time plants had it was when CO2 level in atmosphere was up to 8 000 ppm, 20 x more than today, it was millions of years ago. That's when ferns grew as large as trees. CO2 molecule is one of the most important molecules keeping this planet alive, CO2 is a molecule of life.
Here is a research paper to show how low CO2 atmospheric levels are at the present time, in fact it is so low that plants cannot grow to full potential. And, we won’t see this on TV for some bizarre reason.

CO2 sequestration in plants: lesson from divergent strategies, pages 481–496 (2011), S. K. Vats, S. Kumar, P. S. Ahuja in Photosynthetica (2011)

“Most organisms inhabiting earth feed directly or indirectly on the products synthesized by the reaction of photosynthesis, which at the current atmospheric CO2 levels operates only at two thirds of its peak efficiency. Restricting the photorespiratory loss of carbon and thereby improving the efficiency of photosynthesis is seen by many as a good option to enhance productivity of food crops. Research during last half a century has shown that several plant species developed CO2-concentrating mechanism (CCM) to restrict photorespiration under lower concentration of available CO2. CCMs are now known to be operative in several terrestrial and aquatic plants, ranging from most advanced higher plants to algae, cyanobacteria and diatoms. Plants with C4 pathway of photosynthesis (where four-carbon compound is the first product of photosynthesis) or crassulacean acid metabolism (CAM) may consistently operate CCM. Some plants however can undergo a shift in photosynthetic metabolism only with change in environmental variables. More recently, a shift in plant photosynthetic metabolism is reported at high altitude where improved efficiency of CO2 uptake is related to the recapture of photorespiratory loss of carbon. Of the divergent CO2 assimilation strategies operative in different oraganisms, the capacity to recapture photorespiratory CO2 could be an important approach to develop plants with efficient photosynthetic capacity.”

 

aquanoobie

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Please share such research. Always willing to learn more.
Curious what research is this?
This research paper talks about higher CO2 levels inhibiting aquatic plant growth. Who would have thought?

“The critical values of CO2 lay approximately between 0.6 to 1.0 mM (26 to 44 ppm CO2). At this critical CO2 concentration photosynthetic rate reached its maximum and then decreased with increasing CO2.”

1 mM = 44 ppm CO2


 

GreggZ

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This research paper talks about higher CO2 levels inhibiting aquatic plant growth. Who would have thought?

“The critical values of CO2 lay approximately between 0.6 to 1.0 mM (26 to 44 ppm CO2). At this critical CO2 concentration photosynthetic rate reached its maximum and then decreased with increasing CO2.”

1 mM = 44 ppm CO2


The problem with scientific studies is that they may or may not haven anything to do with the species we grow and the way we grow them in glass boxes.

But either way the bigger issue is that folks have little idea what their actual CO2 levels are. It's an educated guess at best without the proper test equipment. So someone thinks they are perfect at 30 ppm, but the reality may be quite different.

In the long run the preciseness has little to do with keeping a great planted tank. Like most things in this hobby it's more about relative values.
 

Yugang

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If you really want to optimize CO2 a calibrated good quality probe is best
Could you elaborate what is meant with 'optimize'? Is it to target a certain CO2 ppm level, and what level would that then have to be? Or is it about stability during the lights-on? Or a combination of both? If you had the hypothetical perfect pH probe, what is it that you like to achieve when 'optmizing'?

My point is that perhaps you don't even want to know your exact CO2 ppm, many different levels can work as long as they are balanced with other parameters in tank? I am therefore less focussed trying to know the absolute value, and more so on the variations in time and place. These variations I find a bit hard to read on the dropchecker, easier on the probe. Am I at 20 or 30 ppm - frankly I don't care as long as it is stable.
 

erwin123

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Could you elaborate what is meant with 'optimize'? Is it to target a certain CO2 ppm level, and what level would that then have to be? Or is it about stability during the lights-on? Or a combination of both? If you had the hypothetical perfect pH probe, what is it that you like to achieve when 'optmizing'?

My point is that perhaps you don't even want to know your exact CO2 ppm, many different levels can work as long as they are balanced with other parameters in tank? I am therefore less focussed trying to know the absolute value, and more so on the variations in time and place. These variations I find a bit hard to read on the dropchecker, easier on the probe. Am I at 20 or 30 ppm - frankly I don't care as long as it is stable.

ph-profile-28-dec-21-jpg.jpg

This pH profile can be improved' because pH is still dropping after the lights turn on.

ph-profile-2-jan-22-jpg.jpg

By turning CO2 on earlier, I ensure that max CO2 is available when the lights turn on
 

aquanoobie

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The problem with scientific studies is that they may or may not haven anything to do with the species we grow and the way we grow them in glass boxes.

But either way the bigger issue is that folks have little idea what their actual CO2 levels are. It's an educated guess at best without the proper test equipment. So someone thinks they are perfect at 30 ppm, but the reality may be quite different.

In the long run the preciseness has little to do with keeping a great planted tank. Like most things in this hobby it's more about relative values.
Choosing to ignore the researched topic and stirring the discussion to insufficient number of studied plant species and glass box excuses?

The study is about high CO2 inhibiting aquatic plant growth. It has been observed and studied. And the study has demonstrated how higher CO2 levels can be detrimental to aquatic plants. Levels of 30 ppm and higher, recommended by some, can actually be causing more harm than good this study suggests.

I kind of expect, though it takes time, to see posts like, Full CO2, 1/2 CO2 and 1/4 CO2, to gain popularity.
 

aquanoobie

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My point is that perhaps you don't even want to know your exact CO2 ppm, many different levels can work as long as they are balanced with other parameters in tank?
This must be it. When I look at ADA success with CO2 injection timed with lights on and off, and no pH probe. No CO2 tunnel vision approach.
 

erwin123

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The threadstarter MrTank says he has 9 different tanks, some tanks appear to have 30pm-40ppm, and he also has this special tank with 150ppm CO2.
Assuming that the other tank parameters are roughly the same and the major difference is the CO2 levels, then we can see for ourselves the difference between 150ppm CO2 and 30-40ppm CO2 once he posts photos of his tanks.. He can also share with us his own observations on how 150ppm CO2 has affected plant growth.

Even if it is not actually 150ppm, I presume he is pumping into that tank a whole lot more CO2 compared to the other tanks where he has 30-40ppm CO2, so we can still look at the difference between 30-40ppm and a whole lot more (even if not 150ppm)....
 

GreggZ

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Choosing to ignore the researched topic and stirring the discussion to insufficient number of studied plant species and glass box excuses?

The study is about high CO2 inhibiting aquatic plant growth. It has been observed and studied. And the study has demonstrated how higher CO2 levels can be detrimental to aquatic plants. Levels of 30 ppm and higher, recommended by some, can actually be causing more harm than good this study suggests.

I kind of expect, though it takes time, to see posts like, Full CO2, 1/2 CO2 and 1/4 CO2, to gain popularity.
Observed and studied? In an aquarium? Not even close. What does any of your arguments have to do with presenting a planted tank that someone would aspire to? IMO you may not be able to see the forest through the trees.

Arguing about levels of CO2 that can only be measured in a lab have little to do with growing plants in an aquarium.

And I am sorry I am not familiar with you. Can you show me something you have created that I would be interested in learning more about? I am eager to learn from those that are successful in growing plants. Show me something and it would be a more interesting discussion.
 
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