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Effect of CO2 on Plant Growth at Low Light

40K views 161 replies 30 participants last post by  mistergreen 
#1 ·
Years ago Ole Pedersen, et.al, wrote a scientific paper about Liebigs Law of minimums, related to light and CO2. Later the paper was simplified and was available on Tropica's website, as http://www.bio-web.dk/ole_pedersen/pdf/PlantedAquaria_2001_2_22.pdf In that article was a table of data showing the effect of light and CO2 on Riccia growth rates. That table was:


After studying that data for awhile I decided to plot it on a graph in a different way to see what I could learn. That gave me this:


This shows me that, for Riccia, it takes very little CO2 to get the full benefit of CO2 at light intensities up to at least 90 PAR, very high light. One reason for this is that Riccia is a low light, slow growing plant. It is reasonable to assume that other low light, slow growing plants would have given similar results.

Even high light plants, or fast growing plants probably give similar results, but with somewhat more CO2 needed to get the maximum growth rate. I grow Hygro corymbosa siamensis in my 30-35 PAR tank, and I see a similar result as that shown for Riccia.

I started growing the Hygro with no CO2, just Metricide as a carbon source. For over a month the Hygro struggled to grow, getting only a little bigger in a month. So, I added DIY CO2 at around 1 bubble per second. The Hygro immediately started growing much faster, so much so that I have been pruning about 4-6 inches off each plant every week.

To check how much I had affected the amount of CO2 in the water I put 0.5 dKH water in a drop checker and used it to monitor the CO2. With that low KH water, the range of measurement for CO2 is about 1 ppm to about 15 ppm. The first thing I noticed is that, with no CO2 on, the amount of dissolved CO2 rises back to around 3 ppm by the time I turn the lights back on, then drops down to around 1 ppm by the time the lights go off. That means the plants were using up the CO2 early in the photoperiod, something Diana Walstad also discovered in her research. (Her solution was a long rest period between lights on intervals, so the substrate could generate enough CO2 to restore the 3 ppm.)

With the CO2 on all day, the amount of dissolved CO2 goes to around 6-8 ppm. So, my improved growth of Hygro is caused by adding less than 10 ppm to the water. The other plants in the tank also are growing and looking much healthier with the CO2 on.

This was found to be the case years ago when DiY CO2 was first used. But, people continued to want more and more, so they increased their light intensity substantially, along with the CO2, and found that if they had 30 ppm the plants would grow much better at high light, and the fish would not be killed by the CO2. We then seemed to forget about the original benefits of CO2 on low light tanks.

I'm posting this to suggest that we stop telling folks that they need pressurized CO2 if they want to see any benefit in large tanks. It just isn't true. If we stick with low light, probably up to at least 40 PAR, we can gain big benefits for almost trivial additions of CO2, as long as we also dose Metricide or Excel, to stop the fluctuations in CO2 from triggering BBA attacks. This will greatly improve our success rate with our low tech tanks, and increase our enjoyment of the hobby.
 
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#3 ·
Forget adding CO2 and just blast the light. You'll get much faster growth. That's shown in the growth charts. Pedersen explained why in the paper. Applies to other plants as well. High light requires high CO2? Only if you still believe in grandpa myths. "Science progresses one funeral at a time." - Max Planck. Looking forward to some funerals so this hobby can advance.
 
#4 ·
High light results in algae unless the plants are growing in good health. That requires that they have enough carbon available for the plants to do so. Even with low light the plants can strip the CO2 from the tank. I have to disagree with you.
 
#5 ·
High light does not result in algae. That's another myth that needs to die. Excess nutrients, with light and CO2, results in algal growth. Algae are opputunistic organisms. They multiply when conditions favor their growth, which is a good thing since they remove excess nutrients. As long as there is a steady supply of nutrients, and as long as it doesn't become toxic, they grow.

Nutrients, light and CO2 are all required to culture algae. Limit CO2 and growth is proportionately limited. Same for the other two.
 
#6 ·
If light energy drives demand(it does) for more CO2 and nutrient's than is available for plant's to draw from ,then algae which need's much less of everything ,will find excellent environment for proliferation.
Limit lighting, and increase CO2 availability, and provide basic nutrient's, and plant's will respond favorably with little if any algae.
Or you can choose to become a student of way's to combat various algae while blasting away with the light.
Your choice.

Bump:
High light does not result in algae. That's another myth that needs to die. Excess nutrients, with light and CO2, results in algal growth. Algae are opputunistic organisms. They multiply when conditions favor their growth, which is a good thing since they remove excess nutrients. As long as there is a steady supply of nutrients, and as long as it doesn't become toxic, they grow.

Nutrients, light and CO2 are all required to culture algae. Limit CO2 and growth is proportionately limited. Same for the other two.
Yes algae multiply when condition's favor their growth.
Excess lighting,low/inconsistent CO2,and or possible nutrient limitation = poor plant health, which in turn trigger's many form's of algae.
 
#7 ·
I'm posting this to suggest that we stop telling folks that they need pressurized CO2 if they want to see any benefit in large tanks.
Well .. not quite true.. Pressurized CO2 can be run at trivial rates....like 1/2BPS..or less
To me pressurized CO2 is about convenience, regulation and repeat-ability. not to mention necessary for high pressure diffuses........Best to just mention that high CO2 concentrations may not be necessary..or even wanted..regardless of the light..
Now this really doesn't "quite" apply but I'm posting it just to show how things can become.. err.. unexpected..
But results from the third year of the experiment revealed a more complex scenario. While treatments involving increased temperature, nitrogen deposition or precipitation -- alone or in combination -- promoted plant growth, the addition of elevated CO2 consistently dampened those increases.

"The three-factor combination of increased temperature, precipitation and nitrogen deposition produced the largest stimulation [an 84 percent increase], but adding CO2 reduced this to 40 percent," Shaw and her colleagues wrote.
Climate change surprise: High carbon dioxide levels can retard plant growth, study reveals : 12/02
 
#9 ·
Well .. not quite true.. Pressurized CO2 can be run at trivial rates....like 1/2BPS..or less
To me pressurized CO2 is about convenience, regulation and repeat-ability. not to mention necessary for high pressure diffuses........Best to just mention that high CO2 concentrations may not be necessary..or even wanted..regardless of the light..
Now this really doesn't "quite" apply but I'm posting it just to show how things can become.. err.. unexpected..

Climate change surprise: High carbon dioxide levels can retard plant growth, study reveals : 12/02
Rubisco mechanisim in aquatic plant's is said, according to paper's on the topic, to take maybe week's to adapt to fluctuating CO2 level's or sudden shift's high to low CO2 level's, or vice versa.
Perhaps this contributed to observation that increase in CO2 brought no more improved growth over how long??
Or there was simply no more growth because the plant(s) studied had reached their potential height?
If Rubisco mechanisim is working hard to produce enzymes and suddenly more CO2 is available,then the enzyme production is not needed as urgently, and rubsico mechanisim adapt's accordingly and some lag time with growth could be expected?
Same lag time with sudden decrease in CO2 availability while enzyme production might need ramped up?
Surely some speculation on my part , but is a hint of supporting evidence which is more than some provide.
 
#8 ·
@Hoppy: good chart as it visually helps to understand the basic concepts.

The biggest point I got from it is how ROI is scewed: we go to much higher light and co2, at considerable labor and cost, to get that "extra" 1 -5 % in plant growth. It certainly upholds the old wisdom of the 80-20 rule.

I also find it telling how high ligh trails behind medium light curve until it catches up at that magic 30 ppm. I am guessing that the lag is attributable to the plants getting nutrients limited at higher light. All of this gives more support to Mr. Barrs' observations and decades-long assertions on light/co2/nutrients "arms race".

One area where our deductions might differ revolve around ricca as a test subject. My understanding is that ricca is closer to a marginal plant and actually derives more benefits from higher co2 then others. If that is indeed the case, then the benefits of much higher light and co2 would be even more questionable.

My personal experience with hygro corymbosa also differ a bit from yours: mine is currently under medium light, no injected co2, Excel twice a week at recommended dosage and all 5 of my plants grew 200-300% over the last couple of months. Given that, I would suspect that there is another variable between our conditions.

As in other discussions on the subject, yes - there are a lot of beatiful plants that do much better as emergent plants that we are trying to force 100% under water. They are the ones that we are trying to fool with high light and high co2. Luckily for us, there are a lot of more "reasonable" plants to chose from.

As to @Solcielo lawrencia, you might be right or you might be wrong but your message gets overwhelmed by the antagonistIc delivery style. I do want to hear your ideas and your rational for them if I could only filter them out from the noise.
 
#13 ·
@Hoppy: good chart as it visually helps to understand the basic concepts.

The biggest point I got from it is how ROI is scewed: we go to much higher light and co2, at considerable labor and cost, to get that "extra" 1 -5 % in plant growth. It certainly upholds the old wisdom of the 80-20 rule.

I also find it telling how high light trails behind medium light curve until it catches up at that magic 30 ppm. I am guessing that the lag is attributable to the plants getting nutrients limited at higher light. All of this gives more support to Mr. Barrs' observations and decades-long assertions on light/co2/nutrients "arms race".
Look more carefully at the chart. The growth rate on that chart is shown as the percent of the maximum growth rate at that light level. It shows how much CO2 it takes to get the maximum growth rate the light level permits. With very high light, that maximum growth rate is very high, and it takes a lot of CO2 to reach it. With low to normal high light, that growth rate isn't nearly as high, so it takes a lot less CO2 to reach it.

My interest is in low to medium light tanks, solely because I don't enjoy battling algae problems, and the lower the light level the fewer algae problems pop up. This chart clearly suggests that we can use almost trivial additions of CO2 and still get almost as good a growth rate as we would get if we followed the myth that 30 ppm is what is needed for CO2 to be effective for all light levels. I don't dispute that many plants need high light and high CO2 to reach their potential growth rates and beauty.
One area where our deductions might differ revolve around ricca as a test subject. My understanding is that ricca is closer to a marginal plant and actually derives more benefits from higher co2 then others. If that is indeed the case, then the benefits of much higher light and co2 would be even more questionable.

My personal experience with hygro corymbosa also differ a bit from yours: mine is currently under medium light, no injected co2, Excel twice a week at recommended dosage and all 5 of my plants grew 200-300% over the last couple of months. Given that, I would suspect that there is another variable between our conditions.
I'm not sure our H. corymbosa experience is much different. I like having to prune the plant every week or two. Over a couple of months my H. corymbosa also roughly doubled in size, but other plants in my tank just didn't look healthy. Clearly, other species would react to CO2/light somewhat differently than Riccia did, but I believe my experience with H. corymbosa shows that the difference, for that plant, and thus likely for many low light plants, isn't much different.
As in other discussions on the subject, yes - there are a lot of beautiful plants that do much better as emergent plants that we are trying to force 100% under water. They are the ones that we are trying to fool with high light and high co2. Luckily for us, there are a lot of more "reasonable" plants to chose from.

As to @Solcielo lawrencia, you might be right or you might be wrong but your message gets overwhelmed by the antagonistIc delivery style. I do want to hear your ideas and your rational for them if I could only filter them out from the noise.
 
#11 ·
What is the point of continuing to use Excel? Excel is a algaecide rather than a carbon source. I think this is the root of the myth that CO2 prevents algae versus people recognizing the situation for what it is. Yes, a carbon source will help speed the growth of plants which in return will deplete nutrients so algae is kept at bay, but that doesn't happen overnight.

What is even more interesting about these types of experiments is that there is never any mention of how CO2 is being grabbed from the atmosphere. I'm not convinced that if a tank is in a room that never gets aired out via a open window does not see a increase of CO2 levels. Of course depending on where a person lives plays a key role as the air out in the middle of nowhere in Nebraska is going to be much different than downtown NYC.

The tanks we keep are not closed, sealed systems. Water grabs all kinds of things so I'm not sure why people would think CO2 is only limited to what comes out of a plastic bottle or canister.
 
#14 ·
What is the point of continuing to use Excel? Excel is a algaecide rather than a carbon source. I think this is the root of the myth that CO2 prevents algae versus people recognizing the situation for what it is. Yes, a carbon source will help speed the growth of plants which in return will deplete nutrients so algae is kept at bay, but that doesn't happen overnight...
One more conspiracy by a large corporation lying to the ignorant consumer in order just to make a profit?
 
#17 ·
The main myth that needs a funeral is that plants somehow "out compete" algae for nutrients, and therefore keeping nutrients low somehow starves algae.

Nothing wrong with keeping nutrients low if plants are healthy. I dose low levels of certain things myself. But it is literally impossible to run a tank lean enough to "starve algae".


Sorry for getting off track Hoppy. Thanks for doing that chart, this is a very interesting thread.
 
#23 ·
@Hoppy, wow, that is exactly the same attitude that keeps these myths alive. You learn a lot from replicating experiments, not just doing novel ones. The Pedersen paper contains a lot of knowledge, most of which are overlooked or ignored even after I specifically pointed them out. This is a reading problem, or reading comprehension problem, or just a lack of thinking coupled with confirmation bias.
@brandon133, your assumption that pearling is the result of oxygen saturation is only partially true. Inject pure o2 in o2- depleted water and it will remain a bubble. It will not dissolve completely preventing any bubble from forming. Why? Because o2 is being added faster than the rate of dissolution. This is true for plants producing o2 faster than can be dissolved in the water.

Pedersen explained that higher light improves CO2 assimilation even under low co2 conditions. Try the Riccia experiment and you will see this for yourself. You will probably be amazed that Riccia is able to pearl so much without adding any CO2. It's able to do this daily and you'll see that it grows faster than you may imagine under these conditions. Then, with an airstone and tubing, exhale to add your respiration CO2 into the water. Riccia will pearl even more and grow even faster. If you want to see just how much co2 blowing through an airstone adds, measure the pH drop. Also note one thing throughout these experiments: where's the algae that's supposed to be growing under high light (SUNlight) and no added co2?

Pedersen explains that under low light and low co2, plants need to expend energy to gather both which it may not be able to do so to support its growth. But if co2 is increased even just a little, it's able to spend more of the energy to gather the limited amount of light. But the other way, just adding more light, works even better.
 
#24 ·
Just throwing this in for fun..

Plant responses to low [CO2] of the past - Gerhart - 2010 - New Phytologist - Wiley Online Library
I always like these "you need" or "you don't need" discussions ..

Now it would be hard to argue a glasshouse is not high light..........
In another study of a closely allied species, Yan et al. (2006) collected turions of Vallisneria spinulosa from Liangzi Lake, Hubei Province, China, and planted them in tanks containing 15-cm-deep layers of fertile lake sediments, topped with 40 cm of lake water, that were placed in two glasshouses - one maintained at the ambient atmospheric CO2 concentration of 390 ppm and the other maintained at an elevated concentration of 1000 ppm - where the plants grew for a period of 120 days, after which they were harvested and the dry weights of their various organs determined. As they describe it, this work indicated that the "total biomass accumulation of plants grown in the elevated CO2 was 2.3 times that of plants grown in ambient CO2, with biomass of leaves, roots and rhizomes increasing by 106%, 183% and 67%, respectively." Most spectacularly of all, they report that "turion biomass increased 4.5-fold," because "the mean turion numbers per ramet and mean biomass per turion in elevated CO2 were 1.7-4.3 and 1.9-3.4 times those in ambient CO2."
CO2 Science
 
#27 ·
Best to concentrate on the message, not the messenger..
Growth Response of a Submerged Aquatic Macrophyte to Atmospheric CO2 Enrichment Reference
Yan, X., Yu, D. and Li, Y.-K. 2006. The effects of elevated CO2 on clonal growth and nutrient content of submerged plant Vallisneria spinulosa. Chemosphere 62: 595-601. What was done
Turions of Vallisneria spinulosa Yan were collected from Liangzi Lake, Hubei Province, China and planted in fertile lake sediment 15 cm deep topped with 40 cm of lake water in each of a number of tanks placed in two glasshouses, one of which was maintained at the ambient atmospheric CO2 concentration of 390 ppm and one of which was maintained at an elevated concentration of 1000 ppm for a period of 120 days, after which the plants were harvested and the dry weights of their various organs determined.
What was learned
Yan et al. report that "total biomass accumulation of plants grown in the elevated CO2 was 2.3 times that of plants grown in ambient CO2, with biomass of leaves, roots and rhizomes increasing by 106%, 183% and 67%, respectively." Most spectacularly of all, "turion biomass increased 4.5-fold," because "the mean turion numbers per ramet and mean biomass per turion in elevated CO2 were 1.7-4.3 and 1.9-3.4 times those in ambient CO2," All in all, these several changes resulted in a greater allocation of biomass to belowground structures. In addition, it was determined that nitrogen concentrations in leaves and turions were reduced by 13% and 16%, respectively, while phosphorus concentrations were increased in all plant organs by between 35% and 147%.
What it means
The three Chinese researchers concluded that because "both the number and the size of turion, the most important storage and reproductive organ, increased significantly" in the elevated CO2 treatment, this phenomenon would enhance the "population-increasing rate of V. spinulosa ... in the next growth season and would benefit its dominant species role."
http://www.sciencedirect.com/science/article/pii/S0045653505008350
 
#28 ·
Nice to see all the usual suspects gathered around here. I suspect if I covered up the names I could still guess who is who, with the usual trash talk etc.

Thanks to Hoppy for working on the data. I do think that even small additions of CO2 help a lot with plant growth; such that using soil decomposition in a low tech tank can provide a small but significant boost to overall plant health in the tank.

Does this mean that using a lower water to soil ratio enhances the effect?
It also reminds me of Bucephalandra farms where they do "wet emersed" cultures; growing Buceps in shallow water - does this allow better gas exchange
https://www.youtube.com/watch?v=t0ulJOTOdjo


I think another interesting environment to study with regards to higher light, low CO2 combination is outdoor aquatic plant farms.


The ones doing submerged growth here seem relatively clean, good growth forms without CO2 injection. Under puny partial shade, still probably more than 1000 PAR and soaring temps/high 80s into the 90s.

 
#29 ·
I was thinking of emailing Florida Aquatic Nurseries and asking them how they fertilize their plants. They also grow plants submerged in large open containers using sunlight. SUNLIGHT!
https://youtu.be/7Nkfys5hqPs

How does Tom Barr explain that? If 150PAR requires 50-70ppm of CO2, then these containers must require at least 600ppm of CO2, which is well above atmospheric concentrations. Boom. Falsified. PhD revoked.
 
#30 ·
If you want Tom Barr to explain that I suggest asking him.

I much admit that I am troubled by your enthusiasm for putting people down instead of contributing data, experiences, and experiment results. My interpretation of the data in Pedersen's paper is right or wrong regardless of anyone's opinion about me or about Tom Barr or about you. It it is wrong someone should offer an explanation of that data showing where I am wrong. When that happens I will be quick to change my interpretation. Remember, my only goal was to get my low-medium light tank to do better, while entertaining myself by using DIY CO2. It was my results that caused me to look into it further. I didn't know what you thought about the subject, nor did I have any reason at that time to care. We are not in a mano to mano contest here.
 
#31 ·
One thing I've learned on this forum is that if you offer rational, evidence based arguments that contradict prevailing dogmas, you'll be trolled. This and other forums are not the place to discuss real knowledge that is backed by science. When actual science is presented, few ppl have the ability to even comprehend it. Instead, they interpret it the way that fits their prior beliefs. The Pedersen article has been used by Barr and EI disciples to claim plants need high co2 when there's high light. (That's how I first learned of the article.) But is that actually what the article states? Does it even imply that? No to both. I don't think most ppl even read it for comprehension because to do so takes way more time than the time it takes to read it. The fact that you actually took the time to try to comprehend makes you an anomaly. Welcome to the dark side.

As for Barr, he has no explanation. That's the reason why he revoked my mod status on BR, because I stated that CO2 isn't critical. He further had the gall to rub it in. So if something contradicts dogma, ignore it and go on as usual, repeating the same claims as before: high light requires high CO2. Hopefully, and I think this is his goal, that if he just repeats himself over and over and show pictures of his coloful tanks, ppl will gullibly believe him. Funny, too, because he accused Amano and ADA of using nice pictures of tanks just to sell their products. Hypocrisy: Barr does exactly the same thing to sell the idea of EI. Result? Most Americans can't seem to grow plants and have algae farms. Then they blame deficiency or not enough CO2 when they should be blaming EI. Proof? Look at all the threads in the algae and plant forums.

Anyway, I just wanted to rant. Thanks for listening. But welcome to the dark side. If you dig deeper, you won't be able to go back to where you are right now. So you can take the blue pill or the red pill. Ignorance is bliss. Knowledge is a pain.
 
#32 ·
One thing I've learned on this forum is that if you offer rational, evidence based arguments that contradict prevailing dogmas, you'll be trolled. This and other forums are not the place to discuss real knowledge that is backed by science. When actual science is presented, few ppl have the ability to even comprehend it.
The problem is as usual you present information in the wrong context for a planted tank hobbyist forum. It's pretty much examples that you either have no proof of or are not in any way realistically applicable to the planted tank community. How 'bout another salmon Study?

BTW you used to do the same thing in the Aquascaping thread here at TPT a year or two ago. You would rip apart newbies trying to get some basic aquascaping instructions. You treated their tanks like they were trying to break into the top 10 of the IAPLC Contest. And then they would ask to see some examples of your tanks and of course, you never complied. Sound familiar to what your doing now.
 
#39 ·
I'm posting this to suggest that we stop telling folks that they need pressurized CO2 if they want to see any benefit in large tanks. It just isn't true. If we stick with low light, probably up to at least 40 PAR, we can gain big benefits for almost trivial additions of CO2, as long as we also dose Metricide or Excel, to stop the fluctuations in CO2 from triggering BBA attacks. This will greatly improve our success rate with our low tech tanks, and increase our enjoyment of the hobby.
Good conclusion but I wouldn't say stop using pressurized CO2, but maybe stop pushing the CO2 saturation to 30+ppm. There is no need for plants and would cause health issue for livestock. As some have mentioned pressurized CO2 is a convenience and isn't that expensive in the long run. I personally have stopped using extra CO2 or carbon source since regular natural CO2 systems are good enough.
 
#44 ·
I hope I never tell anyone that there is only one road to success with a planted tank. It is obvious that many people succeed with wide variations in how they set up and manage their planted tank. What I will stop telling anyone is that "you can't use DIY CO2 on your 75 gallon tank, unless you use multiple gallon bottles of yeast/sugar water". I am quite sure now that, even with a 75 gallon tank, if you are using low to low-medium light (about 25 to about 40 PAR, measured at the substrate) you will see a significant improvement in the plants with even a single 2L DIY CO2 bottle, or around 1 bubble per second of CO2, but you will probably also need to dose Excel/Metricide at about 1 ml per gallon of water, to avoid BBA, and that improvement may be enough to cause you to enjoy your hobby a lot more.
 
#48 ·
but you will probably also need to dose Excel/Metricide at about 1 ml per gallon of water, to avoid BBA, and that improvement may be enough to cause you to enjoy your hobby a lot more.
I wonder if you even need Excel. I have tanks that have no BBA with high lights, natural CO2. I wonder if supplying a low/constant CO2 24/7 would be the key.

I don't like the noxious chemicals in excel/metro.

Bump: Also when you guys are debating CO2 concentrations, don't confuse ppm in the AIR and ppm in the WATER. They're usually different units of measurements, AIR being ppm by volume and WATER being ppm by weight.
 
#45 · (Edited)
FWIW, I think the cartoon at the bottom of the article is a bit tongue in cheek. Call it levity, humor or sarcasm, but I don't think the authors were making a reference to the how much CO2 we need in our tanks.

Well, after being educated by mistergreen, I'm going to have to edit this post before word gets out and my reputation as one of the more brilliant guys on TPT is tarnished, lol. My apologies to anyone who's bubble has burst. At the moment I only feel remotely comfortable with my comment about the cartoon and I'm kind of wavering on that too :confused1:.
 
#46 ·
When I first tried co2 on my 75 it was via two 2L bottles of DIY. Soon went to four, but even that first week with two brought about an explosion of growth and color. Had about 60 PAR at the time, also dosing Excel (Metricide) at 2x the recommended daily dosage.

Had amazing success really, which was surprising after all I'd read about DIY for larger tanks.
 
#63 ·
If you were aerating the water very well, I suspect what you would see is the color remaining almost the same, vs. going slightly more yellowish green if the water isn't being aerated. in other words you should be able to reduce the drop in CO2 content from the plants using it up by doing a really good job aerating the water. But, you couldn't raise the CO2 content above about 3ppm by aerating.
 
#68 ·
The real world oceans are nothing like our artificial world planted tanks. Oceans are loaded with life, all of which emits CO2, and dead organisms all of which breakdown into a chemical soup including CO2. I'm not surprised that ocean surface waters can contain more CO2 than the atmosphere above contains. But, I had no idea it had that big a "surplus".
 
#71 · (Edited)
The real world oceans are nothing like our artificial world planted tanks. Oceans are loaded with life, all of which emits CO2, and dead organisms all of which breakdown into a chemical soup including CO2.
Actually none of that is not present in our tanks..
Only on a smaller scale

I believe a lot of the world's CO2/carbon is locked deep in the ocean (algae/plankton matter). The rise in temp causes release of CO2.

Point is it is "possible" that tanks could have conc. of CO2 in excess of equilibrium..
Probable???
how much CO2 is produced from fish and bacterial "gunk" in the tank vs turnover and plant utilization..
Certainly not as much as in "winter" or heavily polluted waters.. but..

On the flip side I also see the possibilty of exhausting CO2 in a tank.. ;)

I suspect one of the reasons there is "questions" regarding CO2 injection is for this very reason.. Natural replacement by.. stuff..
Even to the point of possibly exceeding equilibrium..

Depends a lot on the tank..
 
#72 ·
I must say that the start of this thread was a bit of a riot and thus was fairly entertaining and interesting to read. :grin2: The data was also pretty intriguing - I've never seen a plot like that before, and now I'm definitely convinced that for optimal results, I should probably get a CO2 system, and not necessarily apply in huge concentrations.

But if I've understood correctly, the two main take aways are:
  1. Small amounts of supplemental CO2 drastically increases plant growth/health under low(er) light conditions
  2. and it's important to avoid strong light without CO2 added

Does this mean that I could possibly get away with growing HC in an environment with no artificial CO2 sources? What does it mean for plants that have been traditionally "high light"?
 
#73 ·
Can somebody explain the connection between low CO2 and BBA?

My tanks have always been low tech with no CO2 added and I've never had BBA in my tanks. I've had diatoms and green spot algae, that's it. Phosphates dealt with the green spot although there is middle ground there. Too low / algae if phosphates get to high... algae. Diatoms are from too many organics in the water. That is simple enough to deal with assuming the water being put into the tank isn't full of organics as well. I digress.

This low CO2 = BBA is much like the myth that low nitrates cause BGA. I don't understand where that comes from either. There are plenty of planted tanks around that keep low nitrates ( including my own) that don't have issues with BGA. Tanks that are maintained do not have this issue. Tanks that are not being maintained do. It's not a nitrate issue, it's a husbandry issue.

If people want to use Excel, then so be it, but if there is going to be a end to the days of blinding fish because it isn't necessary to begin with, I think it would be great to put a end to some of this other stuff as well.
 
#75 ·
Can somebody explain the connection between low CO2 and BBA?

ll.
I have the same experience. I only got bba in my high tech tank, not my low tech. I won't pretend to know what's going on but I'll guess that the low constant co2 doesn't trigger bba to bloom while the abrupt co2/ph swings in the high tech triggered the bba to bloom.

I'm staying away from excel as well, never mind the fish, what about my health.

Sent from my iPad using Tapatalk HD
 
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