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Re: [APD] plants, algae competition

>From: "S. Hieber" 
>CO2 is a nutrient, why is compeititoin an issue for that but ot other nutirients? >What roles to do all the various >other chemicals play? What are the controls.
  I do not say CO2 was something algae was competing for with plants.
  Algae are not CO2 limited in aquariums if most cases.
  Plants typically are. 
  Adding CO2 will grow both algae(with high light) and plants better. 
  But, it takes ___longer for a plant to adapt to low CO2 or varying levels of CO2 than algae__.
  That is the difference and that has been shown experimentally in genetic inducible signalling in macrophytes and microphytes. A few search functions will show many algae and the rates of this switch. Algae, Carbonic anhydrase, bicarbonate usage, macrophytes:
  Plants and algae have the same or very similar CA, so there is a difference in the response times.
  Two things: genetic upregulation and surface area to volume ratio. 1000000 little algae cells vs a plant stem, which has much more exposure to the environment? Obviously the algae, the plant's stem is the only surface in which uptake can occur. Then the CO2 needs transported to the rest of the plant. 
  CA is expensive if you do not need it for Carbon uptake(say when there is a lot of CO2 present), so the plant/algae gobbles it up and rides on easy street in times of plenty.
  When the CO2 is low, the plant/algae upregulates CA. This is genetically controlled and takes some time to adapt to a given set of CO2 levels.
  Plants have a far greater demand and other CO2 issues than algae(transport, far more biomass to support and maintain) 
  More ref's on the topic.
  Oh, you really should read this one if you like CO2 mist.
  A control is simple, high stable CO2 or no CO2 additions(and no water changes so the plants have stablized). I've done that.
  The treatment is varying the CO2 peroidically.
  I did not do that in that experiment, but........we all have likely done this enough to know what happens, and I've done it on purpose to induce BBA and to shop BBA will grow under such conditions.
  If anyone feels this is a myth, they are welcomed to see if this does not hold true. 
  But few are willing to induce BBA to their tanks on purpose, so lots of talk, little do.
  Still, their observations and the after effect, stablizing CO2 to high levels and then they no longer have algae issues, does say a lot for support of such a theory/hypothesis.
  Sure makes a lot more sense and works in practical application than limiting NO3/PO4/Fe etc.
  See the difference in algae control using the notions I've suggested vs limiting methods.
  >I'm not criticizing what Tom is doing, 
  haha, you know you wanna:)
  >but I don't want to see leaps to cold fusion based on trial and error without controls. >Lots of info is gained this way in the hobby and lots of myths, which are slowly >sorted out over time.
  Well, folks have repeated the CO2 thing so many times and I've solved so many BBA issues with a very high success rate(I'd be higher if it were not for the human factor).
    See above controls.
  I also did this with only algae.
  High CO2 and low CO2 did precisely what I said above, the algae grew the same(Different species though), thus one may conclude, the algae are not CO2 limited. Aeration was added, no plants where present.
  Try this with plants now. You will see dramatic growth rate differences. 
  Again, no surprise.
  Now, trying varying the CO2 level....
  Then you can see what occurs. 
  Algae bloom. 
  Poor plant growth(but slightly better than no CO2).
  In tanks where no CO2 is added to a non CO2 and no water changes are done for long peroids, the plants adapt to low CO2. They grow slower as does the algae.
  Algae like changes and these are different for each type of algae, otherwise there would only be one species of algae.
>If you try something and it works, that's great, but the result, on it's own, doesn't >*prove* the hypothesis.
  Yep. The theory of gravitry is just a theory after all, but we still fly in planes don't jump off cliffs without ropes, parachutes, bungees or water below. 
   In fact, the most common mistake we all make when looking >at the results of something is to commit the fallacy of assuming the consequent.

  Tom Barr

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