What exactly causes BBA?

Discussion in 'Algae' started by Zak Rafik, 29 Mar 2015.

  1. Marcel G

    Marcel G Guest

    One more thing as to the CO2 concentration: In one of my articles I try to show that for aquatic plants to grow well they don't need to reach 100% growth rate, but they can grow at 30 or 50% and be in very good condition also. If you look at the "Dependency chart of external nutrient concentration on the growth rate of plants" in this article, you'll see that if we apply it to CO2, then for plants to grow at 100% they would need 26 ppm of CO2 (this number is just fictional), but for them to grow at 90% they need only 11 ppm of CO2, and for them to grow at 50% they will be just fine with 4 ppm of CO2. So tell me, please, what growth rate is "bad" according to you ... 30%, 50%, 70%? When do the plants suffer? If plants grow at 50% of the maximum growth rate do they already suffer? Do all the plants need to grow at 100% to be perfectly healthy? Or can they be healthy at 50% growth rate also? The answer to this question is crucial. Because if plants can be perfectly healthy at 50% growth rate, then they don't need as much CO2 as you may think! And did you know that most aquatic plants grow at 100% under 40 ppm of CO2? In other words, 40 ppm of CO2 is maximum they are able to utilize. If you read the article you will find out that once the concentration of free CO2 in water exceeds the critical limit of ~40 ppm, an immediate and quite dramatic inhibition of photosynthesis (growth) comes about. So do you still think that there is such a thing as suffering of our plants due to low CO2 in planted tanks where the CO2 concentration is higher then 10 ppm?
     
  2. parotet

    parotet Member

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    I think the two last posts from Marcel point in a very interesting direction. The concept of "Nature Aquarium" may be very attractive but it is just a fallacy, nothing is more artificial than what we do. Trying to compare nature/tank conditions or how our plants behave in nature/tanks is nothing but a nonsense, at least if we go into details (of course plants are plants, and molecules are molecules). Some of the "slight" differences of our "Nature Aquarium" and nature:

    - most of the plants we use spend part of the time emersed, but we keep them most of the times (or always) submerged. And you know what? Truly submerged plants are really easy to grow!
    - they grow in nature under much higher PAR values
    - they grow with a flow that would be unachievable in our tanks
    - they grow with much lower CO2 levels
    - we want them to grow without algae (please have a look to any river, pond, etc.... algae DO live with macrophytes!)
    - we want to grow in a tiny cube plenty of different species (most of the times only a few species live together in nature, the most adapted to the micro conditions)
    - we want to grow them nice of course (good shape, good color, etc.) but plants in nature look quite poor sometimes (but even though they multiply, so this "bad shape" has nothing to do with biological success)
    ... and probably a lot more differences

    We are just finding the conditions to make this "miracle happen", and of course it is obvious (at least to me) that to grow this "Unnatural aquarium" there are several options.

    Another example: farmers grow edible plants. All these plants come from nature of course. Do farmers copy the conditions in which the wild relatives of these cultivated species grow? Of course, not. Because their objective is to maximize the yields, therefore they focus on that. They create conditions that are really different for meeting this objective.
    Are our "Nature Aquarium" so different. Not at all... Nature Aquarium is a good marketing argument (you know "contact with nature", "a piece of nature at home", etc.) but the truth is that we have an objective that is very close to farmers, we also try "to maximize our yield"... yes, we want to trim plants, we want to obtain tones of algae-free plants. That is what is considered successful when you have a high-tech planted tank... but this is not nature, so let's focus on this.

    (sorry, a bit out of topic I guess... :rolleyes:)

    Jordi
     
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  3. Jose

    Jose Member

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    Because co2 levels are not stable in our tanks. If levels were stable enough then most plants can be grown with 10 ppm of co2. Also if dosing EI then we dont have limitting nutrients. So, please look at all variables of the ecosystem so that you can understand it.


    Yes plants can be covered in algae and still look healthy. Because there is the time variable. Something might have happened before to spike the algae. Once algae is there it will just grow. Plus suffering plants is probably not the only cause. Also dirty water for example can spike algae. The theory of suffering plants is mostly for when you have a well maintained tank not limitted by nutrients.
     
  4. Jose

    Jose Member

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    I think the co2 level depends on how much light you have. Demand from plants can be 10 ppm yes or 80 ppm depends on quite a few things. Many can even adapt to 1 ppm. But we also have plants in our tanks that are not found underwater for a long time.

    What you say about 40 ppm inhibitting photosynthesis just does not stand. Otherwise people wouldnt see such an obvious increase of growth at those levels. Im going to read the article because this is just not true if you have non limitting nutrients. You have to once again look at the whole picture and how the experiment was carried out. You are arriving at wrong conclusions. Ask yourself...was everything else independant? enough nutrients? enough oxygen at night? You are missing something.
     
  5. EnderUK

    EnderUK Member

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    I don't know my growth rate as and I don't try to measure it, I have no idea what my CO2 is, as you say there's not really a reliable hobby measurement but I know it's lower then what is EI recommended. My flow is around x 6-8 turn over and I dose around 2/3s of EI when I'm dosing EI but about x2 the amount when dosing PPS-PRO. This would be a complete disaster if I did one thing, up my light intensity or had an incredbly long photo period. My understanding is that light is main cause of algae when you can not get the neutrients including that CO2 to your plants quick enough. You seem to have gotten around the high CO2 needed by most by increasing the flow ensuring that there is a constant supply of niutrients.

    The only algae I seem to get is GSA on my anubias.

    I'm pretty sure it's been brought up many times on this forum that what we do in our tank is not natural. I brought it up in this very thread but not as in depth as Jordi.
     
  6. Marcel G

    Marcel G Guest

    Jose, look at all the variables yourself in the first place! I am perfectly able to keep stable CO2 levels in my tank. Besides, there is a lot of people who use non-stop CO2 supply in their tanks which means they have very stable CO2 level. It really seems you use whatever argument to prove that 10 ppm and healthy plants is not possible in our tanks. I gave you already some arguments, but you seem to ignore them ... trying to "explain them out". Once you understand how CO2 behaves in your tank, it's very easy to keep it stable. Again, look at this article.
    From your post it seems also that you think that plants in a river are somehow nutrient limited. But nothing could be farther from the truth. In rivers plants have tons of nutrients available (especially in amazonia).
    Again, again, again: Try to speak with some experts on aquatic plants, and ask them how much CO2 is non-limiting for most of them under full sunlight. I did it, and present the results of their research and practical experiences in field. Dr. Adamec is one of them, and he recommended me to use 0.2-0.3 mM CO2 (which corresponds to 9-13 ppm of CO2) for a good growth of aquatic plants in our tanks. These values should be enough for most plants to grow at 70-90% of their maximum growth rate (according to him). He specializes on studying bladderworts (strict CO2 users which are not able to use carbon from bicarbonates).
     
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  7. Jose

    Jose Member

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    You dont get it Ardjuna. Its very simple. You are right because you are testing "easy" aquatic plants. We in the hobby grow much harder species which grow better the more co2 you put in. Because they live semi emmersed most of the time.

    Ill tell you something and this is asking you a favour:

    Maybe for the future we (you or me) can try an experiment. We can get the hardest plants that we can think of and try to grow them at very high light (maybe around 100 PAR) whilst supplying EI nutrients or more if you want. We can try keeping co2 at 10 ppm. Will they grow fine in your opinion?

    If you have just one hard plant in your tank you have to get conditions as good as possible for that plant, even if the rest can grow at much lower values.

    By the way. Most experts on this topic are biased and havent contributed very much to it. They are mostly old school and still think that high nutrients cause algae. They cant really make for any useful breakthroughs because they are just outdated. It will take some time for new theories to catch up. Until researchers in universities start realising this.
     
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  8. parotet

    parotet Member

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    I guess he has already done this... while most of us have done nothing but to chat. Look for another loooong thread about EI/Tom Barr/etc he began some months ago, also in his website. Amazingly, and despite the personal effort done, money spent and sharing, people still dare to criticize. Yup, most of us do not read scientific papers about the topic, we do not spend our spare time talking to experts, we do not spend our time making experiments... but it's really easy to post and give our opinion which is just a mantra we have well learnt.

    I did it in the mentioned thread, but once again I reiterate my thanks to someone that does this. I would not venture to say "you're wrong" to Marcel, Clive, Darrel, Tom Barr or anyone else. I am not able to even scratch the surface (what's my experience? Am I a pro? what's my field of expertise? How many tanks have I runt?). This is why I just try to understand them... when I can :p. l am actually happy to encounter contradictions in what I know/read from them, that means that I don't really know that much!

    Jordi
     
    Last edited: 31 Mar 2015
  9. sciencefiction

    sciencefiction Member

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    Well if the question is about BBA, then how would low CO2 levels be causing that, or poor plant health. Having kept low tech tanks I have had both scenarios and poor plant health does not equal algae and specifically not BBA. You can have perfectly stuggling plants and not one bit of any algae, at least in a low tech tank. I don't think CO2 and BBA are correlated at all. Poor plant health leading to high organic load as in a high tech tank, maybe.

    Has anyone tried to trigger BBA or remembers the sequence of events prior to getting BBA?

    I remember Darrel stating somewhere that nutrients dissolve in water equally, meaning flow has no effect on nutrients. CO2 and oxygen are a totally different story, as they are not so easily dissolvable. So as long as one doses nutrients in the tank, there shouldn't be any nutrient deficiency regardless of flow.

    And then if you've got 10ppm of co2 at any given time then how would there be CO2 issues or defficiencies in the tank? If you need to pump 30ppm maybe that means most of it is going out the surface and never gets to the plants. It doesn't make sense that if you have a constant supply of co2 regardless of the total value and never running at 0 at any given time, then plants are getting co2 theoretically all the time, whether the water has a concentration of 30ppm, 10ppm or 5ppm
     
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  10. Another Phil

    Another Phil Member

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    Hi all,
    I think one of the problems with the scientific method is that it relies on replicable results, and all our tanks are so different it is near impossible to precisely replicate someone else's results, so therefore we all holler when results are different.
    Currently we appear to be at the level of Sir Isaac Newton, his physics is accurate 99% of the time, but there were still discrepancies which were partially resolved by Einstein and relativity, then by quantum mechanics, and now there are as many theories about dark matter/dark energy/string theory/multiverses as there are physicists;)

    I think of algae as opportunists, so there could easily be 4-5 triggers which have to coincide before they bloom. We don't even know if GSA in our different tanks are the same species in the same genus, so each similar species could react differently.

    cheers phil
    ps. EnderUK was ref'ing Monty Python - made me laugh.
     
  11. Jose

    Jose Member

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    Its funny I dare all people who coincide with Ardjuna to go ahead and keep a high tech with highish light at 10 ppm CO2 and come back and post. Do you not think that the 30 ppm of co2 came by through experience and trial and error? Of course it did.Come on. They didnt come to the 30 ppm number by looking at rivers or asking algologists.

    To Parotet. I do apreciate all the effort Ardjuna has gone through to get all his data. But the main thing is you have to be critical. And for that you have to understand first. All this effort doesnt make something right.
     
  12. Jose

    Jose Member

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    This is from Ardjunas link:

    At pH 8, even at the extremely high alkalinity 28°dKH, there's only 8.5 ppm of free CO2 in water. Therefore, there's no growth inhibition → see the upper left portion of the chart.
    At pH 7.0, the photosynthesis (growth) rate reaches its maximum (critical level) at a concentration of 26.4 ppm of free CO2 (which corresponds to alkalinity of 8.6°dKH).
    At pH 6.5, the photosynthesis rate reaches its maximum at a concentration of 41.8 ppm of free CO2 (which corresponds to alkalinity of 4.3°dKH) → see the bottom left portion of the chart.
    At pH 6.0, the photosynthesis rate reaches its maximum at a concentration of 41.8 ppm of free CO2 (which corresponds to alkalinity of 1.4°dKH) → see the lower right portion of the chart.

    Why is KH changing here? This experiment should be done at the same KH, adding artificial CO2 (and measuring it). CO2 does not change KH. I dont get it.
    Your charts show total inorganic carbon. This include carbonates (?). So they are upping co2 by breaking up carbonates?

    towards the middle of the page.
    http://www.prirodni-akvarium.cz/en/rostlinyNaroky
     
  13. dw1305

    dw1305 Expert

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    Hi all,
    Flow does have some effect, particularly if you add the fertiliser as a dry salt, you can think of it like stirring your tea.

    If you have perfectly still water it will take much longer for the salt to go into solution as ions, and there will be a circular concentration gradient around the site where the salt was added. In still water the salty water will be dense than the fresh water, and will pool at the bottom of the container (tank), which will also slow down the rate that mixing occurs.

    Once the salt has fully disassociated (and some salts will go into solution more quickly than others), it will be spread fairly evenly through the water column, even with very low flow rates. Once salts are in solution they will usually remain in solution, until they are taken up by a plant etc..

    Dissolved gases are slightly different in that they are in part of a dynamic equilibrium with atmospheric gas levels, and they can enter and leave the tank dependent upon the diffusion gradient between tank water and the atmosphere.

    cheers Darrel
     
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  14. Jose

    Jose Member

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    Ive got a side question. Does anyone know why Plantbrain doesnt post here anymore?
     
  15. pepedopolous

    pepedopolous Member

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    The plot thickens...

    I'm gonna set aside the time to read Marcel's new articles properly.

    Tom Barr wanted to relieve hobbyists of the need to repeatedly measure nutrient levels with (inaccurate) test kits. The flip side is that many hobbyists struggle to provide enough CO2/flow/magic fairy dust.

    I wonder if somehow the 'lean ferts approach' of ADA means that while CO2 has to be 'good', it doesn't have to 'perfect' (unattainable to some), as seems to be the case with EI.

    P
     
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  16. Jose

    Jose Member

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    I ask myself this question too. Tom Barrs EI method doesnt necessarily have to be the easiest but it is the most complete for a high tech. Ive had bad results when limitting nutrients before but Im still open to the idea of limitting via phosphates.
     
  17. Another Phil

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    I assume also that if the water is perfectly still the plants use CO2 and that leaves a deficit of CO2 next to the plant leaves, so they have to rely on CO2 diffusion through the water, hence there could be a slow uptake of CO2 in what appears to be high CO2 water and that's why high flow helps?
    cheers phil
     
  18. Rahms

    Rahms Member

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    Potentially, but I think its more the fact that if a high concentration of CO2 is poorly mixed in the tank, it will rise and gas off at the surface faster. Rather than it being there, the plant using it up and then it not being replaced (as in your example), it's simply never there to begin with.
     
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  19. dw1305

    dw1305 Expert

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    Hi all,
    I think so, the other advantage of high flow is that it increases the residence time of the CO2 bubbles, meaning that more CO2 will go into solution.

    I'm not a CO2 user, but if I was I would want a system (Bazooka Atomizer Diffuser or similar) that produced a CO2 bubble "mist" to allow me to see where the flow went.

    cheers Darrel
     
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  20. dw1305

    dw1305 Expert

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    Hi all,
    Certainly will. If you don't have much flow the bubbles will just rise straight to the surface and be lost. Because of the area to volume ratio you want very small bubbles with a very long residence time.

    Even then, in water the uptake of CO2 is limited by slow diffusion through the plant cell wall (obligate aquatic plants don't have stomata). The diffusion of gasses in water is several orders of magnitude slower than it is in air.

    cheers Darrel
     
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