CO2 and Plants

Discussion in 'Planted Tank Equipment' started by Warren, Sep 21, 2006.

  1. Warren
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    Warren Noob

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    After several water changes, I was able to observe that the small bubbles begin to form,if they form at all, before I begin adding the water change water.   The only difference in the tank conditions is that the water level is now below the output of the power heads which run the UGF.   So, I deduce that the increased surface agitation from the powerheads has caused an increase in the dissolved air content of the aquarium water.   Whether this air is increasing the CO2 availability to the plants, leading to increased photosynthesis, or whether the air is simply precipitating out on the plants is unresolved.

    This phenomenon has LED to the following line of thought.   One approach to managing CO2 availability for aquarium plants is to elevate the levels of CO2 in the tank artificially, then limit CO2 exchange with the atmosphere by limiting surface agitation.   This limits the depletion of CO2 availibility by the plants during the day.   In the absence of such a strategy, we are all aware that in the relatively still water of a home aquarium, diffusion is the only mechanism to replenish carbon dioxide,and is woefully inadeuate for the job.  


    What if, on the other hand, CO2 were kept at ambient levels during the day by vigorous aeration of the water surface?   Although not as beneficial as the elevated CO2 levels obtained from gaseous injection, wouldn't a continually available few ppm of CO2 give a boost to most aquarium plants?  

    It seems to me that the other side of the CO2 merits some thought; i.e., is it possible to increase the ability of plants to use the CO2 already available in it's environment, rather than increase the CO2 availiable to the plants?   I think both approaches get you to the same place, if they can be implemented.

    Any Thoughts.

    Regards,

    Warren
     
  2. Andre
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    Andre Green fingers

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    Hi Warren

    Ambient CO2 levels in water is around 4ppm. Normally in a high light setup you are aiming for 15 - 25ppm CO2. For a low tech - non CO2 - setup your idea has merit and will probably work well, but it wont be able to get to the levels needed for a hight tech setup.

    HTH
     
  3. Cameron
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    Cameron Green fingers

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    Vigorous agitation of water will saturate it with O2, the pearling from the plants after a water changfe is visible as the water has been super saturated and cannot hold any more gas, so instead of the water absorbing the O2 from the plants it escapes from the leaves as bubbles.

    Correct, ambient levels are generally about 2ppm in any tank with low surface agitation.

    Obviously it would add a couple more ppm for sure, but this is not enough to sustain the plants (if you are running good lighting levels), on a very low light tank it will be sufficient enough to grow slow growers like Anubias and Crypts, java ferns and mosses.

    Generally 2-4ppm is not enough to sustain a well planted tank, with good light levels and photoperiod you need to try and stabilise CO2 at 25ppm the entire photoperiod.

    Regards
    Cameron
     
  4. Andre
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    Andre Green fingers

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    We posted at the same time and said the same thing :p - COOL :p
     
  5. Cameron
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    Cameron Green fingers

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    Synergy R us.com :)
     
  6. Warren
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    Warren Noob

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    Thanks for the prompt feedback from you guys. It was just a thought on smaller tanks that are lightly planted.
     
  7. Cameron
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    Cameron Green fingers

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    Warren, your reasoning is sound, it will help, but don't expect the plants to grow crazy like they do with artificial CO2 injection.
     
  8. Philip
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    Philip Algae harvester

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    Hi cameron
    I read your article which mentioned UGF, well there is so much debate with reference to UGF, that I actually proved it to a customer who wanted a planted tank,all his plants started rotting, even Vallisneria, a hardy plant just wilted, his Amazon swords looked extremely bad. I proved to him if I remove the UGF, because plants do not like movement near there roots that he will see a marked improvement, and wow, he was amazed.So what I am trying to say is , anyone wanting to use UGF may do so , but from my personal experience if you can do without it, you will see the results.
     

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