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How much "K" is used up during the day?

Discussion in 'Estimative Index' started by rick4him, Sep 21, 2008.

  1. rick4him

    rick4him Prolific Poster

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    I know this is hard to tell, but how much K is normally absorbed during the day?

    How many ppm of "k" do you normally add to a tank?
     
  2. aaronnorth

    aaronnorth Prolific Poster

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    well it depends on the dosing, if you dose EI, then you cant really tell (unless someone has worked it out - Tom??) because you are also dosing NO3 & PO4. Some people also dose KH2SO4, in which case would raise the ppm again.

    although the reccomendation is 30ppm.
     
  3. detlef

    detlef Subscriber

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    As far as K+ Tom found 0,25 to 1ppm of daily uptake. I measured a mean 0,9ppm uptake per day depending on plant growth, density and species.

    Edward over at APC recommends about 1,4ppm of daily additions whereas Amano adds more than double of that. His recommendation hovers around 3,4ppm/d.

    K+ levels should not be critical at all as long as there is "enough" for the plants all the time. I estimate that Kalium should always be kept above 10ppm. Though, ten times more of that was found not to be detrimental.

    Best regards,
    Detlef
     
  4. aquabillpers

    aquabillpers Lifetime Charter Member
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    That's like asking, "How much gasoline will I use?" :)

    The amount of nutrients used by the plants in an aquarium is directly related to the amount of light that is supplied. A 4 WPG aquarium will require more of all nutrients than will a 2 WPG tank.

    People who use EI aren't concerned with that question. Instead, they overdose nutrients and remove the excess with frequent water changes. That isn't scientifically elegant, but it works. elegance: Definition, Synonyms from Answers.com

    Bill
     
  5. Tom Barr

    Tom Barr Founder
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    You can use any of these levels as estimates.............but that's about all they will ever be. Unless you plan on dosing and testing for each tank etc.

    I suggest uptake rates based on what I've seen, I suggest dosing a lot more than the uptake rate for everything other than light.

    Concentrations in the environment for both terrestrial and aquatic species can be 10,000 orders of magnitude difference and has little influence on plant growth rates as long as the supply is replenished.

    The ranges for Fe are even larger, up 10^12 vs what we find inside the plant.
    The whole business about ratios is not supported in agriculture and mineral nutrition(see Epstein and Bloom) Epstein and Bloom are UC Davis professors, Bloom gave me the qualifying exams for the mineral nutrition part.

    As long as there is not osmotic stress due to higher levels, non limiting levels are the key. Measuring biomass at different treatment levels of nutrients and knowing the critical concentrations are also key here. I have serious doubts that ADA, anyone at APC does any dry weight measures, knows the critical concentrations or analyze K+ levels in plant dry tissues.

    I have a few references for aquatics, but those are far and few in between.
    We mostly focus on N, P and Fe. K+ is rarely an issue for horticulture.

    I've never really seen an issue with K+, but many have made claims about it's dramatic magical importance.
    All while not looking carefully at light and CO2:cool:

    I generally have about 20-40ppm of K+ in my tanks and have for a really long time now without any issues with the most difficult plants at the highest growth rates and with 300 species.

    Still, no reason K+ cannot be lower without issue as long as it does not run below say 1-2ppm. How many folks measure K+ at limiting levels in the hobby?
    Not many and even fewer do it critically.

    Regards,
    Tom Barr
     
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