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Magnesium over 10ppm is bad, m'kay?

Discussion in 'General Plant Topics' started by Tom Wood, Nov 21, 2006.

  1. Tom Wood

    Tom Wood Guru Class Expert

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    Someone over at APC posted that some plants stop growing when Magnesium is above 10ppm. (Actual ppm not as CaCO3) True?

    And, that it is -important- to keep the ratio of Ca:Mg in the 3:1 to 4:1 range. True?

    Thanks
     
  2. Tom Barr

    Tom Barr Founder
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    You mean Edawrd posted his R wallichii stopped growing and stunted when he added high Mg to 10ppm.

    I tried this with the same plant, I found no such effect at 15ppm Mg.
    Perhaps he had some other confounding effect he over looked?
    Can he confidently rule this out?
    No.
    I couldn't.
    It would still be in doubt in my mind.
    He made a hypothese, I tested it and did not find it to hold true.
    I'm not saying what stunted his plants, I am saying what did not.
    That I do have much more confidence in than mere speculating the cause.........

    My tap water in SB was a GH of 24 and had a Mg range of 12-20ppm.
    I had no issues with many plants. I had more issues with CO2 namely.

    But I could not discount other possible issues, so I had R wallichii when he posted it, added MgSO4.7H2O to get 15ppm, a good deal higher than the 10ppm suggested, the R wallichii still grew nicely.
    At the time I had near RO like Tap, GH 1 and KH about 2.

    I've seen the plant specifically stunt like the picture, and it was CO2.
    But it might be something else and one thing causing another in his tank.

    Maybe he should switch to EI?

    Regarding ratios of Mg and Ca.
    Nothing in the argiculture field suggest this is critical nor in aquatic systems as long as you do not get too far out there and have things become limiting.

    My bet is you have issues with the CO2 and with the high KH.
    Edward likes RO water and adds basically just enough, and seldom explores the upper ranges, believing them to inherent toxic, bad.

    I'm more practical and willing to try odd things that most folks experience and run into. Many are not willign to buy test kits,RO etc, I know, I tried to ask folks to do it in the past.
    See SFBAAPS for an old reference article.

    There's more to aquatic plants than mere nutrients alone.
    I also have had a lot of experience moving and dealing with a wide array of taps and tend to be somewhat anti RO for all my water needs, having seen and dealt with such issues rather than giving up and going all RO and instisting others buy test kits, calibrate, micromanage, must use RO water for the tank etc.

    Rather than accepting weak inductive reasoning(I observed this, it must be true for all cases), seeing if the hypothese is false or true (actually testing and trying to refrute the hypothese) and stands up to further test allows you to make a much better judgement and tentative belief of what is occuring.

    Then you can show to yourself what is and is not true in your mind and see what makes the most sense.

    This might open eyes:

    Inductive reasoning - Wikipedia, the free encyclopedia

    Regards,
    Tom Barr
     
  3. Tom Wood

    Tom Wood Guru Class Expert

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    Thanks Tom,

    I'm just now getting back to trying to get this tank in shape again, and revisiting things I'd tried before.

    The water here has 83ppm Ca and 50ppm Mg (per water quality report and confirmed by testing) actual ppm not as CaCO3. I've cut it in half with RO and could cut it in half again to get the Mg down close to 12ppm. But the Ca:Mg ratio is still out of whack and I didn't know if it was worth bothering with. I can add CaCl to add Ca back and get the ratio closer to 3:1 Ca:Mg but only if it's necessary.

    TW

    EDIT: It was someone else that brought this up, and when I asked for a reference they pointed at that thread you mentioned with Edward's r wallachi. And so the myth propagates like a weed. :p
     
  4. Tom Barr

    Tom Barr Founder
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    Well,

    Once you start adding ppms to things and causes, you'd better know and be pretty careful how you say it. I was very leary about using specific ideal ppms for planted tanks when I started out with the Article:

    A List of Levels and Parameters:

    References

    So I used ranges which are better than single points.
    I conferred with Steve and other folks for sometime before hand and we came to a consensus based mainly on the plant's responses to nutrients/CO2/light.

    This was 10 years ago.

    Back to the issue: one case is no scientitfic law, it needs to be checked and double checked. Others need to check it and make sure.

    I fully tell folks the ranges I test and measure so that they might be able to use this as a reference and hopefully will test and modify/reject my theories in the future or further confirm them.

    It(Mg excess) seems to be very low IME/IMO to cause stunting(only 10ppm? that's suspect which is why I tested it!), alkalinity is another matter(and has a much higher ppm range before things happen also) with some species, but these are more general for all nutrients when that is added with some of the Rotala species.

    I think if you have 15-20ppm of Ca, ansd 10-12 ppm of Mg, that's fine.

    Think about it this way: how much do you have to have before it becomes limiting? 0-1ppm Ca++ or so.
    How much NO3 can be used in a week?
    Likely more than Ca++.

    You can always add some CaSO4/CaCl2 also.

    Speculations get multiplied rapidly.
    Another similar case was that high K+ causes stunting, that was all the rage about 2-3 years ago by a select few, a few bandwagoning, even though folks had no issues with it for a decade prior. That observation was gleefully tossed out the window:rolleyes:

    I pointed out this but brick wall thinking would not listen.
    "Tom Barr does not know what he's talking about".

    Finally, setting up the experiment again to show it did not occur, I showed I had no such effect. Same with Erik's 100ppm + tank that won best of show in the AGA event in 2001. No peeps from the peanut gallery since.

    Now for that to be accepted as a true theory, why did it only pop up in this select few folks, why right then and why where they so ready to suspend all logic and past work based on a misapplied belief?

    I gave them examples to try out.
    Not one of them ever did a single test.

    Today, do we hear about such poppycock and K+?
    No.....but you have to wonder why not........:rolleyes:

    One example of induction is hardly a precedent for a theory, nor a validation of any hypothesis.

    I think the idea of induction is a huge problem with the production of myths in this hobby. I am very agressive towards these for that reason.
    It's not because, I'm like some, butt head and enjoy messing with people.:D

    PPS was founded on induction rather than deduction experimentation like PMDD and the Sears Conlin article.

    My notion grew out of PMDD and envolved into a simpler version: EI.
    I really did not modify PMDD much, just add a bit more and added more PO4.
    Paul had never said no PO4, just low PO4 was required.
    I saw things differently and was able to show it for that issue.
    So the theory was rejected as to "why", but the how essentially remained fairly well entrenched and is still today.

    Why would an aquatic plant stunt due to higher than 10 ppm of Mg?
    That's an interesting question, so I set out to see if I could see the same thing. While I did not find the same impact as Edward, I can at least say what Mg 's effect is not at a given amount, he still cannot say with certainly what did cause his stunting(a much harder question), although he may want to believe it.

    Thus ruling all possible variations of the hypothesis is a slow method, but a much more careful one.

    I get lucky every so often and find a good cause after trying almost everything else. Lots of work though.


    Regards,
    Tom Barr
     
  5. Tom Wood

    Tom Wood Guru Class Expert

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    Thanks Tom,

    I understand that exact numbers aren't needed, it's just easier to type one number when discussing the math of dilutions.

    BTW, there's another thread at APC where, talking about using Equilibrium to reconstitute RO, they say:

    Squirrelly?

    I've had absolutely no success with Equilibrium, RO Right, or your GH Builder when used to reconstitute RO. Hence my interest in simply diluting the tapwater. And then letting whichever plant that grows best in the result take over the tank.

    PS: Sorry about dragging stuff from APC over to here, but it's relevant and I wanted your opinion.
     
  6. Tom Barr

    Tom Barr Founder
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    No need to apologize about APC here. I do not go there, but hold nothing against anyone that does.

    I'm not sure what George meant by that comment either, I was there as well as several others.

    GH Booster + baking soda or potassium carbonate works fine.
    Cheaper too.

    One for GH and that's better balanced than Eq and the other is certainly cheaper than Seachem alkaline buffer for KH.

    That's what is used to reconstitute in labs or CaCl2/MgCl2 for GH etc.
    Depends on the other ions involved and the test to be done.

    Squirrley is not something I've noted nor had issues with going back about 8 years of wide ranging usage of SeaChem Eq by many members locally and abraod. I have no clue what they are talkign about nor is it wide spread/significant.

    Seems to me, at leats in the context presented here, that they are blaming squirrley behaviors on the wrong defendent once again.:D
    Would not be the first time they they over looked something certainly.

    Given your case: add about 17.9 ppm of Ca from CaCl2 or CaSO4 after the water change would yield the range you seek.
    I do not think it's worth messing with personally though.

    I know you prefer lower CO2 and with harder water, I think the issue is more related to that rather than anything to do with hard GH's.

    One is about 1% at best, the other is 45% of the plant biomass.

    Here's why also:

    You said:
    GH, Eq, RO right(bad stuff all the way around IMO/IME) all failed right? With RO + reconsituation?

    That's very strongly suggest another causative agent for the issue you might have.

    Why?
    Because I've used these and do use them for RO on client's tanks and my own tanks over a very very wide range of GH ranges.

    I've not seen anything I can relate to Ca or Mg.

    Edward does a lot of talking about Ca/Mg and many look at the so called deficiences symtoms from agriculture crops that are used to apply to our aquatic plants.

    CO2 is much more likely to cause such issues and it's presence is far more fleeting.

    The Ca? if you have 20ppm of Ca++, it ain't going nowhere too soon, you add 10ppm 2x week, you can be sure that you have enough of that one.

    CO2? Folks lack such confidence, some squawk to no end, but then the same ardent rigorous tester measures 171 ppm of CO2 and has happy fish and plants, it's hard to accept that all CO2 ppm measurements are correct.

    I've approached the problem from another manner/prespective.

    Try to actively induce and test rather than observe and only test after the problem appears.

    Many times you miss the problem of cause if you approach it with the latter method most every aqaurist ascribes to.

    Add a bit more CO2. Wait 2-3 weeks.
    Next drop the CO2 and see if you might induce the plants to produce such a response.

    Next drop the CO2 another notch down.

    This way you have a good base line prior to starting and can see what and where things went wrong.

    You may rule out the Ca++ theory in this manner by showing this alternative hypothese to be valid and often times even more valid than the original hypothese, Ca++ ratio imbalances, high Mg whatever.....was causing you the issue.

    Scientist are clever because they look for all these possible alternatives and test them as well as the more traditional ones. Leave no rock unturned.

    This allows you to get at truth, or at least much closer to truth, than the latter.

    Logic and methods escape many hobbyist frustrated and wanting resolve.
    I do try and point out such methods and simple alternative methods for hobbysist to try and test themselves to show such points. Many do not do such test sadly. This ends up with me being the only guy doing the test and I'd rather discuss things with folks that do the test etc. That gets weird and I'd rather have more folks test and prove things to themselves rather everything being based upon what I have done, yet while some may point this out, they do nothing to rectify it either:rolleyes:
    Tom Barr may not see the real cause and that may hold true no matter how hard I try.

    So I leave post about how some rather simple methods and logic to illustrate this and a hobbyist can certainly do such test themselves and make the same observations and see that the alternative hypothese might be more valid.

    So try the CO2 metrhod, you';ll elarn more and get a better handle on things no matter what by exploring CO2 and giving it a good revisiting, I've done this many times and gone back to square one. While I arrive at the same place, I always see something new;)

    Make the assumption that the Ca/Mg are fine rather than bad.
    Go after the CO2 and assume it's too low. See if you can measure a decline in Mg or Ca. See what the N drop is and if it correlates well with Ca and the ratios of N:Ca in many macrophytes.

    Traces are yet another issue, switch to TMG etc vs Flourish.
    That will be your next alternative hypothese or you can try and rukle that out now as well and add more, see how easy the nutrients are?
    CO2 is more prickly.:mad:

    Regards,
    Tom Barr
     
  7. Tom Wood

    Tom Wood Guru Class Expert

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    Yeah, I'm trying to rule out issues rather than place blame on any one.

    I did upgrade to a 20lb CO2 cylinder so I could crank it up. I placed a Sweetwater stone inside the filter intake pipe, and if I listen closely I can hear it when it's on, there's that much coming out. I marked the needle valve where the fish goes wonky, and I always get at least a 1.0 pH drop, so I think I'm good there.

    I upgraded the lights to ludicrous speed with 1x175W 14K MH and 1x250W 65K MH lamps on Icecap ballasts. Since this tank is effectively an 80 gallon because of the in-tank sump at one end, that works out to better than 5 WPG of high PAR lights.

    I've calibrated my NO3 and PO4 test kits and I know I'm good there. I dose KNO3, monosodium phosphate (Discus Buffer) and K2SO4 per the APC fertilator.

    After all this, most of the plants just yawned. The Mexican Oak Leaf (s rivularis (sp?)) is doing the best and does grow wider/pinker leaves lower in the water with the new lights. Since it's native to these waters that made me want to reconsider the Ca/Mg thing.

    I currently use an alternating combo of Flourish and CSM+B. A switch to TMG would be the final thing to change, I'll give it a try.

    If I'd done all this when I was in Austin, I'd be hacking the plants back with a Texas chainsaw. :D We made the one move in the one direction in the one place in the entire US where you can pass through all the water quality zones and go from the best water to the worst water in less than 100 miles:

    [​IMG]



    Thanks again Tom, always illuminating as usual!
     
  8. Tom Barr

    Tom Barr Founder
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    We know eachother enough to rule out such thinghs, CO2 is really all that is left here. TMG is a pretty good deal Greg might carry it if I hear back from him.5 liter jugs are decent deal.
    That will rule out most things.

    From there, adding a carbon filter to the tap would be the next thing.
    With that much light and ferts, the CO2 demand is really quite high.

    I have a client's tank with 4x 250w + 8x 55w PC's and add about 10-14 large bubbls/sec. That's light CO2 also:rolleyes:

    Regards,
    Tom Barr
     
  9. Tom Wood

    Tom Wood Guru Class Expert

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    What would that be for?

    I cut the water again with RO, so now it's (mathematically calculated) down to about 20ppm Ca and 12ppm Mg. It measures at about 6 dGH and 2 dKH.

    After the dilution I got a fizz factory of pearling yesterday and today, mostly out of the Mexican Oak Leaf, but still no significant leaf growth. The red plants, mostly ludwigia species, aren't budging at all. I'm ready to dump them, but the plant I want most to get going is plain old hygrophila difformis. I know what this plant is capable of doing, and this ain't it.

    Same pattern as I've had for some time, a spurt of activity after a change, then a steady decline into choking by the green fuzz algae that follows green dust algae. If I could get the fast leaf growth I've had in the past, the plants out run the algae and it can be physically removed into oblivion.
     
  10. Tom Barr

    Tom Barr Founder
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    The Carbon would remove any unknowns from the tap.
    I do not think there are any(it's a possibility, remote I'd say), but the CO2 is the more likely culprit.

    I'd just tweak the CO2 more, be very critical of that, the nutrients/Ca/Mg etc you can be pretty confidient about.
    I use to Keep Riccia as the CO2 indictator, no pearling most of the day, not enough CO2.
    Pearling most of the day? Enough.


    Regards,
    Tom Barr
     
  11. Tom Wood

    Tom Wood Guru Class Expert

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    The other high concentrations in the tapwater are sulfate at 132ppm, sodium at 21ppm, and chloride at 19ppm. Wouldn't removing traces with carbon negate the point of using tapwater?

    Another thought - I'm using Discus Buffer which is monosodium phosphate for phosphate. Is it possible that it is complexing with other things in the water in a way that makes it show up on the test kit but not be available to the plants? The reason I ask is that green dust algae is prevalent and some folks have luck getting rid of it with elevated phosphates. (With this latest dilution though, even the GDA is hurting.)
     
  12. trcpdx

    trcpdx Junior Poster

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    I see this assertion made quite frequently. However, I've looked all over for references to data showing that activated carbon materially impacts trace levels in actual planted aquariums, and I haven't found any. My limited understanding is that acticated carbon has the highest affinity for adsorbing organic and high molecular weight inorganic compounds, like mercury. Still, I have heard of many aquarists who report using carbon part or full time with no difficulty maintaining thriving planted tanks.
     
  13. trcpdx

    trcpdx Junior Poster

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    I believe that many municipal water treatment systems already use carbon in the filtration process, prior to disinfection and the addition of other compounds such as flouride.
     
  14. Tom Wood

    Tom Wood Guru Class Expert

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    I had much better success with Austin water, so I looked at the Austin water report again and was surprised to see that they actually invert the Ca:Mg ratio. (The blue boxed vertical column is for the Davis Water Treatment Plant, after treatment.)

    [​IMG]

    If I do another 50% dilution I'll be at about 10ppm Ca and 6ppm Mg.
     
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