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Manganese levels

Discussion in 'Aquatic Plant Fertilization' started by GR1KTR, Aug 19, 2016.

  1. GR1KTR

    GR1KTR Prolific Poster

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    Hi All,


    I use Amgrow Trace Mix to make micro solutions and according to Rotala Butterfly Calc, in order to yield 0.5ppm Fe per dose, I am also adding 0.25ppm Mn per dose ( or 4 doses = 1ppm weekly).


    Here's the product analysis (% w/w) for Amgrow:


    NITROGEN (N) TOTAL % 1.7


    as Ammonium 1.7


    PHOSPHORUS (P) TOTAL %


    POTASSIUM (K) TOTAL %


    SULPHUR (S) % 15.5


    CALCIUM (Ca) %


    MAGNESIUM (Mg) % 7.0


    ZINC (Zn) % 1.006


    IRON (Fe) % 6.063


    COPPER (Cu) % 0.628


    BORON (B) % 0.007


    MANGANESE (Mn) % 1.627


    MOLYBDENUM (Mo) % 0.198


    My questions are:


    - What is the upper limit for Mn dosing in planted tanks? Is there any risk of toxicity?


    - What would plant uptake of Mn likely be at maximum level (say high-light fast growing stems)?


    - What do you think is good target range for Mn dosing?


    Cheers


    GR1.
     
  2. GR1KTR

    GR1KTR Prolific Poster

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    Hi All,


    It's 2 days or so since I posted this with no responses, so I gather I haven't included the right info for you. Please let me know if you need further details on anything, happy to provide.


    I've looked into manganese toxicity to try and establish an upper limit, but most papers relate to terrestrial plants, some aquatic plant stuff behind paywall. One study noted that Mn toxicity (in the Rice Plant) took place beyond 3.2ppm Mn in solution, with plants displaying necrotic brown spots developing gradually from the lower leaves and spreading upwards. Apparently the rice plant is known to be quite tolerant of higher Mn levels, and accumulates Mn in large quantities in the leaves. Interestingly no toxicity symptoms developed at 1ppm Mn, and I hope my plants are tough enough to handle this level too.


    http://www.tandfonline.com/doi/pdf/1....1988.10415580


    A friend from another forum saw my post ^^ and he believes my copper dosing could be too high also. I was adding 0.02ppm Cu per dose, 3-4x per week. Lately I've been doing 75% water changes weekly, hopefully that has reduced the risk a little. I'd greatly appreciate some feedback on this also.


    In the mean time I've halved my micro dosing and made a separate Fe solution to hit my approx level of 0.5ppm Fe per dose.
     
    #2 GR1KTR, Aug 21, 2016
    Last edited by a moderator: Aug 21, 2016
  3. Pikez

    Pikez Rotala Killer!
    Staff Member Moderator

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    You can potentially fry your plants with too much traces. But it's hard to say if this formula is going to do that. But overall, it seems very trace heavy. You may need to more than halve it. If you're concerned, stop dosing for a couple of weeks and do a few large water changes, back to back.


    If there is any way you can use something more tried and tested like CSM+B, that'd be far better. I can grow plants reasonably well with 10 to 25% of EI level traces. Use Rotalabutterfly to figure out where your dosage puts you in terms of percent of recommended EI levels. If you're at EI levels, you're still fine, but even that's way more than necessary.


    I can't speak confidently about Manganese levels, other than to say even half to quarter levels of EI is plenty.
     
  4. GR1KTR

    GR1KTR Prolific Poster

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    Thanks Pikez. I follow your journal (really enjoy it) and have seen the changes you've made to dosing over time, so understand that I can scale back pretty significantly if necessary. I'll drop back to 10% and eyeball things for a little while. A 10% dose will yield 0.1ppm Mn which is the 'recommended level' for EI according to Rotala Calc, though I should probably stop harping on about Mn now and focus on more important things. I'll give the tank a couple of 90% WC this week to flush the system before dosing any more.


    My plants show no signs of toxicity, and IMO all are growing ok at this point. There is some room for improvement though.


    My shrimp are ok but I do feel that they aren't thriving like they used to, so room for improvement there too. Lets see if a reduction in micros makes a difference.


    I'm in Australia so CSM+B would need to be shipped here, which is easy enough. Amgrow is one of the more popular micro-mixes here, as well as Rexolin APN. I haven't seen anyone using CSM+B here but it'd be neat to give it a shot and share the results on my local forum.
     
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