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DOC`s

Discussion in 'Off Topic and Chat' started by brad, Sep 12, 2005.

  1. brad

    brad Prolific Poster

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    What the difference between dissolved organic compounds and dissolved organic carbon? I keep trying to research DOC`s and keep getting horror stories of DOCompounds. Diana Walstad claims DOCarbon are neccesssary in a natural tank. Is there a difference?
     
  2. brad

    brad Prolific Poster

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    Re: DOC`s

    anyone know?
     
  3. Simpte

    Simpte Prolific Poster

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    Re: DOC`s

    I have no idea. I only posted to keep this active. :) Sorry I couldn't be more help.
     
  4. Tom Barr

    Tom Barr Founder
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    Re: DOC`s

    Not much difference.
    Organic means carbon based compunds.............

    Not sure what horr stories are associated with DOC...
    I totally disagree with Diana's statement they are "neccessary" in a planted tank.

    We can do water changes, add activated carbon etc to remove them and maintain them at extremely low levels and actually have better growth.
    That does not match with the observations.

    Do you get better growth after a large water change or right before when DOC will be highest?

    Regards,
    Tom Barr
     
  5. aquabillpers

    aquabillpers Lifetime Charter Member
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    Re: DOC`s

    I am unable to find a reference in Ms. Walstad's book in which she maintains that DOC is necessary in a planted aquarium. Rather, she seems to be saying that it is a naturally-occurrng substance whose main value is as a source of carbon as it decays. It is "just there", as it is in CO2-injected aquaria.

    In a natural aquarium, about which Ms. Walstad writes, the preservation of carbon is very important, since these environments tend to be carbon-limited. Water changes are infrequent, mainly for that reason. In a CO2-injected tank ("unnatural"? :) ) preservation of carbon is irrelevant.


    I would think that if before a water change the water were optimum for plant growth or close to it, replacing that water with something of less quality would retard plant growth, not improve it. If the water in the aquarium were unhealthy, of course a water change would be beneficial.

    But then, after a large water change my heater pearls, so . . . :)

    Bill
     
  6. brad

    brad Prolific Poster

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    Re: DOC`s

    This article was my introduction to DOC`s. I beleive it was written with fish only tanks in mind because I know the author doesn`t keep planted tanks. I`m sure some things cross the boundaries between planted and non-planted tanks though.
    http://www.badmanstropicalfish.com/articles/article23.html

    I`ll have to reread what Diana wrote but I think she considers DOC`s the carbon source in her already carbon limited tanks. Removal would then mean the plant growth would be even slower.

    What role do you think they play in non co2 tanks Tom? And if we do see better growth after a water change as a direct result of DOC removal, how much harm are they doing in our no-water-change setups? Is it even significant?
     
  7. Tom Barr

    Tom Barr Founder
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    Re: DOC`s

    Well if they are oxidized eventually, they can add a little, and I mean very little CO2 source for plants.

    A little more current and turnover etc would do a lot more to add DIC.
    In non CO2 systems, I think they play a minmal role as far as the plants are concerned.

    As far as the bacteria are concerned, carbon is everything.
    Like us eating bread, pasta etc, our carbs...........

    Bacteria can become carbon limited and since non CO2 tanks mainly are a balanced system, the bacteria can use more DOC to help reminerlaize the other nutrients from fish waste.

    In CO2 enriched systems, we cannot wait for this waste to be brokened down since growth is amplified.

    So we add inorganic CO2 and inorganic nutrients.

    Non CO2 can work without any inorganic ferts, but many nobn CO2 tanks cannot grow nearly as many species due to this issue.

    If you add just a little inorganic ferts once a week, then you can grow more species and the plants look better in a non CO2 tank.

    Regards,
    Tom Barr
     
  8. brad

    brad Prolific Poster

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    Re: DOC`s

    So in dumb-dumb language for me, in non-co2 tanks:
    Bacteria convert the doc`s into nutrients for the plants. The carbon they provide is insignificant. If we dose the water colomn with inorganic ferts, the nutrients provided from these doc`s is also unimportant. Did I get that right?
     
  9. Tom Barr

    Tom Barr Founder
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    Re: DOC`s

    for the most part yes, while more important in a non CO2 tank, still not that important as long as you add the inorganic ferts. Bacteria can become carbon(this is not the same as CO2 limited) limited FYI. As long as there is a source, then things will be fine. Plants leak out organic DOC as well, so if the plants are happy, they tend to take care of any bacterial needs.

    Regards,
    Tom Barr
     

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