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Nutrient deficiency?

Discussion in 'General Plant Topics' started by dutchy, Oct 16, 2009.

  1. dutchy

    dutchy Plant Guru Team
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    Hi,

    Can anyone tell me if the pinpoint dots on the leaves of Hygrophila Corymbosa is because of some nutrient deficiency? I dose KNO3, KH2PO4 and micro's according to EI.
    New growth is ok.
     
  2. Philosophos

    Philosophos Lifetime Charter Member
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    Looks like BBA on the edge with GSA in the center and a little hair algae. I'd up the PO4, but more importantly the CO2 based on the picture.

    -Philosophos
     
  3. dutchy

    dutchy Plant Guru Team
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    Leftovers from worse times I guess. The ones shown are very old leaves. New growth is ok.
    Po4 = 1 ppm, Co2 = 44 ppm, circulation 10 x turnover. With 0,1 Ph lower I gas my fish.
     
  4. Philosophos

    Philosophos Lifetime Charter Member
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    You could stand to turn up your PO4 for a bit to eliminate the GSA. Aim for 3-4ppm perhaps. I run about 5ppm at peak and GSA isn't any real problem; the odd leaf at most, the glass if it isn't scraped for a month.

    -Philosophos
     
  5. dutchy

    dutchy Plant Guru Team
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    Thanks for identifying and the advice. I didn't recognize the GSA. I had it before on an Amazon Sword, but looked different. Bigger and darker.
    Will add more PO4 to 3 or 4 ppm. But doesn't that mean I have to go to 30 or 40 ppm on the NO3 at the same time?
     
  6. Philosophos

    Philosophos Lifetime Charter Member
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    Your NO3 uptake might increase, but not by loads. You can increase if you like, but PO4 should already be non-limiting if you're dosing heavily enough; if NO3 uptake increases to deficiency, then you were probably PO4 limiting in the first place. Never the less, increase it as a precaution if you like. There's honestly no harm in dosing 30ppm NO3 in a fast growing tank.

    -Philosophos
     
  7. dutchy

    dutchy Plant Guru Team
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    Thanks. Sorry for not being clear enough....I was reffering to the Redfield Ratio, where NO3 / PO4 = 10:1.

    So PO4=3, NO3=30.
     
  8. Philosophos

    Philosophos Lifetime Charter Member
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    The redfield ratio is only based on dry weight analysis of macro algae. While it holds in FW to some degree, it does not state that a plant will always uptake more nitrogen because more phosphorous is available; there is an upper limiting bound created by fixation enzymes within plants. If the limitation weren't there, then likely plant cell walls would rupture from bad P:Ca:C ratios. This is clearly not the case.

    Another point to take note of is that NO3 and PO4 are not pure N and P. What you're adding with 10:1 NO3 to Po4 looks like:

    NO3: 14.00672/62.00501 g/mol N
    PO4: 30.9737622/94.9714822 g/mol P


    N = 20ppm*14.00672/62.00501
    P = 2ppm*30.9737622/94.9714822

    N = 4.517931696
    P = 0.652275009

    which is more like 7:1 N:p, and is actually what you'll find Tom recommends in his newsletter based on his research and study.

    Keep an eye on your NO3; if it begins to drop, increase dosing. I'm honestly not sure how far or if luxury uptake of PO4 will increase NO3 uptake significantly.

    -Philosophos
     
  9. dutchy

    dutchy Plant Guru Team
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    I was always around a constant NO3=10 and PO4=1 with my dosing.

    So will NO3=10 and PO4=3 give me BGA?
     
  10. Tom Barr

    Tom Barr Founder
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    Yea, it does look like left overs.
    Leaves often just hang there and do not get better really, so we tend to watch just the new growth and trim the older ratty leaves later as things grow in.

    Regards,
    Tom Barr
     
  11. Philosophos

    Philosophos Lifetime Charter Member
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    I can't think of a reason why it would so long as it doesn't go below 10. 5ppm NO3 might be different story; you'd see a nutrient deficiency in the form of yellowing, your plant growth would slow, and algae would take over.

    BGA tends to be something that I see in tanks with poor ciculation more than anything. I'm sure the nutrient levels (besides low CO2) that encourage BGA over other types of algae are far more complex.

    -Philosophos
     
  12. dutchy

    dutchy Plant Guru Team
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    It was a good learning moment to find out the pinpoint dots are GSA, even if it happened in the past. I'm going to add more NO3 and PO4 anyway to see if I can notice any effect on my plants .

    Thanks Philosophos for your detailed explanation.
     
  13. Tom Barr

    Tom Barr Founder
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    Do not worry so much about ratios, there's never been ANY evidence that it holds weight unless you get to limiting levels.


    In other words, 20ppm of NO3 and 20ppm of PO4 are 1:1 ratio, but neither are limiting, likewise, 50ppm of NO3 and 2ppm of PO4 is not either..............

    So there's a difference of 25X, and yet neither case has any limitations if those ppm's remain constant.

    So it's not the ratio, rather, the individual absolute ppm's, see liebig's law of the minimum.

    If every nutrient is non limiting, then CO2/light are limiting growth rate/s.
    If that are saturation points as well, then metabolic functioning of the plant is the limitation.

    Stay away from the Redfield ratio, it causes a lot more trouble and is misused more than any other parameter in aquatic ecology. Even within algae is causes lots of issue since every one likes to refer to it, and yet if you look at ratios and optima for varous algae species, they are really quite different from the RR.

    Same for plants and same for freshwater algae.

    You cannot be so broad in such assumptions.
    RR might help someone grow plants better than say someone who is not adding any PO4, but that is not due to the RR, it's due to the limiting factor(Liebig applies here, not Redfield).

    This guy does not understand this and muck it up even further by assumign mass ratios are the same as atomic ratios:
    Charles Buddendorf, seems he finally added a calculator that has the mass differences included, for a long time there was no difference between the atomic and mass ratios:rolleyes:

    Good to see he finally changed it a few years later.
    Still, we can plug some ppm's in and see there's no risk of the various algal claims there either.

    Ratios can vary over a much wider range than the RR.
    That is something we can consistently demonstrate.

    This would suggest that it's not the ratio, rather, the absolute ppm of each individual nutrient.

    This goes back to agriculture and Liebig, since aquatic plants are plants after all, and we grow them.............

    Just because they are underwater does not change anything.

    Inducement of algae is an entirely different case and the RR is not going to limit algae, it might limit plant growth if you reduce it down.
    After a long while and at a much lower ppm, it will eventually lower and limit algal growth, but plants will stop growing long before that.

    Generalizing too much about all algae and about all plants is oversimplifying things. Each species has it's own set of optima and cues, germination signals, ecological niche that it is best suited to compete in.

    We can take some average, but simply adding non limiting levels for all plants addresses that. So all we need to do horticulturally is find the min upper bound for each nutrient with the other nutrients set as independent/non limiting.

    Then you have a simple easy to target range for growing all aquatic plants.
    Curiously, algae do not grow when this occurs.

    We can induce algae with altering those ranges, really restricting plant growth.
    But is this due to a decline in plant health/growth, or some other cue that algae use to sporulate and recruitment starts?

    What causes the algae to germinate from spores to adults/noxious phases?
    RR does not explain that at all where aquatic plants are present, not in nature not in aquariums.

    It can be used to describe trends in open ocean systems, but with sediments and sources other than the water column, things are not nearly as simple.

    I'd just suggest to stay away from it.

    Regards,
    Tom Barr
     
  14. dutchy

    dutchy Plant Guru Team
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    Loud and clear. :D I'm very curious too see if things improve even more.

    Thanks very much.
     
  15. Philosophos

    Philosophos Lifetime Charter Member
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    Thanks for the clarification, Tom. It's nice to know that luxury uptake isn't going to mess with nutrient demands.

    When you say that Charles Buddendorf was confusing mass ratios for atomic ratios, do you mean he thought hydrogen had the same weight as plutonium? Or is there something profound that I'm missing?

    -Philosophos
     
  16. Tom Barr

    Tom Barr Founder
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    No!

    He thought that mass ratio was the RR!
    It's not, it's an atomic ratio.

    To convert to mass, you need to adjust the N by a factor 30.97 g/mol of P/14g/mol of N= 2.21X off.

    The calculator on his wen site fixed that. I sent him an email some years ago, he did not fix it for sometime.

    I guess he looked into it and got around to it.

    Still does not make any of it right.
    But it does get folks adding N and P at least rather than trying to drive everything to zero.

    The rational behind is wrong however.
    We grow plants first, algae is a secondary thing and has very unique culturing and germination signals unlike any plant.

    We cannot discuss algae in the nutrient context without also discussing plant health when you discuss both in aquariums.

    Any test must also include a control for good plant health/growth as a reference.
    Few even bother to do this and even more lack to control to do it.
    Even fewer bother to test their assumptions, hypothesis to see if they are correct or not.

    Since few do this, there are many nutty brain theories out there, some use references poorly........some see correlation and assume that is cause.

    So getting to the bottom of things is not easy and be careful when folks claim things about algae in general. Most cannot even identify an unknown alga.

    Most aquarist do well with their method when they focus on the plants, noit anything really to do with nutrient control and algae.

    Regards,
    Tom Barr
     
  17. Philosophos

    Philosophos Lifetime Charter Member
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    So then in reality the RR makes for...

    10 N : 1 P = 10ppm N : 2.2113ppm P = 44.2680ppm NO3 : 6.7803 PO4

    More like 6.5ppm NO3 : 1ppm PO4

    That would definitely get people to increase their PO4.

    Anyhow, talking and thinking about more accurate N:p ratios in SAM's is leaving me with several scrapped spread sheets and browser windows poking at questions that leave even more questions. If they were all answered, I'm sure I could save a few mg's of KH2PO4 :rolleyes:

    I think I need to start focusing on individual species more; it'd probably be far more productive.

    -Philosophos
     
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