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Woh! That ratio got way out of wack.

Discussion in 'Aquatic Plant Fertilization' started by Whiskey, Aug 13, 2010.

  1. Whiskey

    Whiskey Subscriber

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    Hello all!

    First some specs.
    I have a 30G Tall tank, with a 55W PC about 12 inches off the water,.. it is a low light tank.
    Growth is steady,.. far less than I saw on my higher light tanks, but that's just what I was going for. Stem plants grow a couple inches a week.
    I have 10X Turn over, with 2 100GPH pumps, and a Fluval 204
    It is CO2 injected, with a drop checker at the bottom of the tank, drop checker is yellow green
    The photo period is 10 hours
    UV Runs for a few hours a night
    The tank is packed with plants - all easy stuff, stems, java fern, Crypt, Anubis, The thin leafed sword etc.
    50% water change weekly.

    I've been dosing 1/2EI for in the neighborhood of 5 months now,.. I tried going up to the full dose at one point as it filled in, but my growth didn't show improvement, and I started getting algae on the glass much faster so I backed off.
    (1/2 EI has been 1/8th TSP K2NO3 - 1/8 TSP K2SO4 - 1/32 TSP CSM+B - 1/32 TSP K2PO4)

    Recently algae has started to creep in, nothing major,.. a little on old leaves, a dusting on glass and equipment. I had a feeling it might be nutrient related so I backed off to one dose per week - that was only last week, but I've seen a minor improvement in the green dusting's growth rate.

    Today,.. I got test kits for Nitrate and Phosphate to try and get a bead on where I am. My results were this:
    Nitrate 10 maybe a touch low, but I'm okay with that.
    Phosphate,.. 10+ It was off the chart. I am not okay with that.

    I don't know how Phosphate got that high - maybe the food I'm feeding,.. maybe I was dosing more than I thought,.. maybe detritus build up? Maybe the plants simply aren't using that much and it's built up despite the aggressive water changes, but it doesn't really matter much.

    My plan is this:
    Massive water change.
    Cut phosphate out of my dosing schedule - continue to dose Potassium, Trace, Nitrate Iron.
    Wait till Phosphate hits 1 PPM, then start dosing at about 1/4th what I was to see if it climbs again.

    What do you think?
    Is 1PPM Phosphate a good number? Is 10-20 PPM Nitrate a good number to maintain?

    What about my Potassium, Trace, and Iron,.. If one is out of whack,.. do you think it could be caused by one of these other things being super low and limiting? Or do you think the traces and Iron could be super high?

    Thanks for your help!
    Whiskey
     
    #1 Whiskey, Aug 13, 2010
    Last edited by a moderator: Aug 13, 2010
  2. nipat

    nipat Guru Class Expert

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    I used to have high level of phosphate too when dosing full EI.
    PO4 in tap water was 0.5 PPM, but the tank had 10 PPM.

    No more PO4 dosing for me now and PO4 in the tank has stabilized at around
    1-2 PPM. I believe it's from fish food. So far so good.
     
  3. csmith

    csmith Guest

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    Don't forget to ensure your tests are good by calibrating them.
     
  4. hbosman

    hbosman Guru Class Expert

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    Don't agonize over high phosphate levels, 10 ppm won't grow algae better than 1.0 ppm for a given amount of light. I would argue that phosphate levels too low for plants will still grow algae nicely on those same plants. Check your light levels and CO2 levels and consistency.

    I tend to dose about 6 ppm kh2po4 per week. Why? Because it's easier for me to measure and sometimes I get spot algae. It seems I get less GSA when I increase my phosphate levels.
     
  5. nipat

    nipat Guru Class Expert

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    My reason is not for algae, but for pH. I know the concept, I read EI method many time.
    I don't believe in limiting PO4 to control algae.
    My KH is very low, I just don't like pH around 5 when adding CO2.
     
  6. hbosman

    hbosman Guru Class Expert

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    Ok, gotcha.
     
  7. Whiskey

    Whiskey Subscriber

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    I understand that by the time I limit PO4 for Algae,.. my plants will be unable to grow,.. but at the same time from what I understand when you have one nutrient super high, without the others being high in the same ratio then you can stunt growth, and encourage algae. I'm not really trying to limit algae,.. I'm just shooting for around 1 PPM which would be in better balance with the Nitrate.

    There is another issue too - My CO2 delivery is based on a PH Probe. Though the drop checker is always yellow-green I'm betting the climbing Phosphate levels are effecting my readings and CO2 levels.

    Whiskey
     
  8. hbosman

    hbosman Guru Class Expert

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    Phosphate does affect ph readings but it sure takes an awful lot to make a significant change in the PH reading.
     
  9. Whiskey

    Whiskey Subscriber

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    That's good to know,.. I thought Phosphate had a greater effect than that.

    So! I did my water change the day I posted this thread,.. and got my P04 down to 1 PPM,.. then I dosed everything else at full EI levels, with and extra 3 PPM Flourish Iron. This got NO3 to 20 PPM, good.

    I tested 2 days later, and my PO4 is still 1 PPM,.. and N03 went down to 10 PPM,.. so I dosed everything but P04 again.

    I have a little green algae visible on the glass after cleaning it 3 days ago,.. I'm not thrilled about that - but it may take a while to subside,.. I'm hoping I found the reason some algae was starting to creep in - and I'm really hoping I caught it in time to avoid any kind of big bloom.

    The plants continue to grow at their steady slow pace,.. and the tank looks good.

    Whiskey
     
  10. Whiskey

    Whiskey Subscriber

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    I think this is actually turning out to be a CO2 and NO3 issue. Turns out that my CO2 level was quite a bit lower than I would have wanted,.. and that when I raised it I was limiting my plants on NO3.

    I have doubled my NO3, and K dosing, Slightly increased my dosing of Iron, fixed the CO2, and resumed dosing PO4 at the old levels,.. this is keeping PO4 and NO3 at non-limiting levels.

    I'll report back on this thread once I dose and test for a week to let you know what I see.

    Whiskey
     
  11. Whiskey

    Whiskey Subscriber

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    That dosing level appears to be spot on,.. I ended the week with 20 PPM NO3 and 2 PPM Po4, both levels non limiting.

    I am still getting quite a bit of green dust algae on the glass though, it has to be cleaned twice a week - I'm not sure what to make of that.

    Whiskey
     
  12. Tom Barr

    Tom Barr Founder
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    It would take a lot more than a few ppm of PO4 to affect the KH.
    If you have a PO4 specific buffer that targets say 6.0pH, then yes, but KH2PO4 by itself...........not much.

    As far a ratio, there's no way it can stunt anything, even over a massive scale for even the worse of dosing issues...........as long.............as the absolute limitation levels are not reaches: eg, not the ratio, rather a specific nutrient is limiting.
    Liebig's law is all about this idea, so leave the ratios out of all this.

    Some find them useful for dosing all nutrients less and less, like a farmer who might spend 80,000$ a season on fertizer and has an econmic interest.
    Us? If we wasted say 20% of the KNO3........so what? It's 2$ a lb for us. Might waste say 40-60 cents a year and not need to test or worry, or waste testing reagents and kits etc.

    Stick with Liebig and leave the ratios alone.
    They are abused to no end on aquarium forums(and elsewhere).

    Regards,
    Tom Barr
     
  13. Whiskey

    Whiskey Subscriber

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    Your talking about Liebig's law of minimum's right?
    http://en.wikipedia.org/wiki/Liebig%27s_law_of_the_minimum

    And saying that provided the plants are not limited by nutrients or CO2 then they will grow at their max rate for the available light, effectively preventing algae from taking hold,.. did I understand that correctly?

    But,.. don't some types of algae take off if one particular nutrient is much higher than the others? Regardless of weather the plants have all they need or not?

    In my case I believe the core problem I was having was CO2 related,.. but I'm talking in general for my future knowledge.

    Whiskey
     
  14. ibanezfrelon

    ibanezfrelon Guru Class Expert

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    No , algae need only very small amounts of nutrients for their maximum growth , something like 0,001ppm of PO4 and 0,01 ppm of NO3...
    ...adding more ferts than they need for max yield will not increase the algae growth.
    When you see those numbers it gets quite obvious that we can't limit algae and keep the plants alive and growing...
    ...and it's clear that the algae doesn't care if the tank has 2ppm or 10ppm of PO4 when algae max yield level is reached already at very low 0,001ppm of PO4 etc...

    To put it simple , i think Tom used elephant and mouse for a comparison..
    Imagine elephant and a mouse , elephant is a plant and mouse is algae.
    They eat from the same bowl.
    Elephant (plant) needs 100kg of food daily and a mouse (algae) needs only 5 grams.
    If you give them 150kg of food one day will the mouse eat the extra 50kg? No, the max he can eat is 5 grams , and he doesn't care about the extra food , he has his 5 grams..
    On the other hand , if you give them only 10kg of food what will happen? To the mouse?-nothing , he will take his 5 grams , but the elephant will be hungry though..

    So , it doesn't matter if one nutrient is much higher , algae always have enough of all nutrients , but for some reason when the plants grow nicely than algae doesn't , and that's why we must focus on plant growth and give plants all they need.

    blank-elephant-m&#111.jpg

    eat-elephant..jpg
     
    #14 ibanezfrelon, Aug 30, 2010
    Last edited by a moderator: Aug 30, 2010
  15. Whiskey

    Whiskey Subscriber

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    Lol,.. You even posted pictures of a mouse and an elephant. That's awesome! :)

    So,.. Okay. You can't limit algae by nutrients,.. I'm totally on board with that.
    If you limit the plants in some way,.. Weather it be by one nutrient, or by a limiting the source of carbon then you give algae a foothold and it takes over. Easy enough.
    Then if you want a slower growing tank,.. and you don't want to use CO2 you make the light low enough so that the plants don't even use up what CO2 is available - limiting them by light before anything else thereby never giving algae a chance. That makes perfect sense, and it works great.

    But! What about in nature? This is the thing that makes me scratch my head. There are streams that get direct sunlight, beautiful plants, and no algae. They probably have nutrients just from runoff, but they don't have a CO2 source,.. how does that work?

    Whiskey
     
  16. Tom Barr

    Tom Barr Founder
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    This diagram explains is pretty much:

    [​IMG]

    Once you hit that C range, adding more, no matter how much..........will not give you a higher rate of growth, algae or plants.
    Both algae and all plants behave this way.

    Now algae will have far far less/lower ranges for these nutrients in ppb ranges, where as plants will have/require a lot more. So each species/stage will have it's own unique graph like this. They have done these types of graphs for most crops, some aquatic weeds.........but.........virtually nothing else, and FW algae are rarely studied etc. so there's scant info out there, but we can still generalize and think about it in these terms.

    The algae really are much lower, so there's no hope of limiting them when we have plants also.
    So.............why do you think many aquarist observe a reduction in algae when they "limit" nutrients?????

    Think about Liebig's law and CO2.
    Treat CO2 like a nutrient, what happens when you limit PO4 more than CO2 for plants????
    Ignore algae, they are reactionary to poor plant health.

    Regards,
    Tom Barr
     
  17. Whiskey

    Whiskey Subscriber

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    Well - taking into account what I just learned if the limitation were to switch from CO2 to PO4 by driving down PO4 levels then the following would become true:

    CO2 levels would rise, because plants demand for it would drop abruptly when the plants become limited by PO4.
    The plants growth would slow, and the plants would begin to compete for PO4; however the Algae would never be limited because it requires much lower levels of PO4 than the plants do. (is that right?)
    Plant growth would slow, and algae would have the chance to take a foothold even though Carbon and other nutreants are plentyful.

    But! If that is the case then lowering levels of PO4, would cause an algae problem to get worse,.. not help solve it,.. Or am I missing something?

    Thanks!
    Whiskey
     
  18. ibanezfrelon

    ibanezfrelon Guru Class Expert

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    Well , the plants can take PO4 limitation much better than CO2 or NO3 limitation..
    ..if you can keep it (PO4limitation) in a C range , moderate deficency range , than you could even loose some algae issues , because CO2 is not limited anymore , now limitation is shifted to PO4 which plants can take much easier..
    This is why people wrongly acuse PO4 for their algae issues , because with dosing PO4 they increase the plant's CO2 demand and not meeting that demand leads to stunted growth and algae issues.. ..at the same time, tanks with good co2 don't have those issues.

    The problem with PO4 limiting is , in the long run it's dificult to keep the tank in that C-range (or sweet spot)... ...and if the PO4 becomes severely limited you have problems..
    As Tom would say - it's bad horticulture.
    Increasing CO2 or lowering the lights is much more rational method.
     
  19. Whiskey

    Whiskey Subscriber

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    So,.. if I'm understanding the information here,.. the trick to ensuring your tank is Algae free, is to make sure that all the plants have non-limiting values of every nutrient including CO2,.. so that they are able to grow as fast as they can given the available light, for the entire light cycle. (meaning the only thing you should ever use to limit growth is light)

    If you limit them by something else, such as C02, or NO3 and it halts their growth then algae can take hold.

    I'm also reading that there is no way currently available to us to limit algae in any way,.. but proper plant growth will halt it in it's tracks.

    I'm also getting out of this that algae will grow no slower, with 0.01 PPM P04 than it will with 20 PPM P04, this goes for all the nutrients as well. As long as the levels are above limiting levels the algae will be able to grow at it's full speed.

    Is that correct?
    Thanks!
    Whiskey
     
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