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Thread: Misuse of "PMDD"

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    Misuse of "PMDD"

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    PMDD stands for Poor Man's Dupla Drops. It actually refers to the recipe of a home-made fertiliser meant to function the same as commercial fertilisers like Dupla (duhz), TMG, Seachem Flourish, etc.

    It was created in the earlier days of the planted tank hobby when commercial aquatic plant fertilisers were few and expensive. This much more affordable alternative was created from loose fertilisers (i.e. KNO3, K2SO4, MgSO4.7H2O, trace fertiliser mix) by Sears and Conlin, and they shared the recipe freely on the Internet. (That paper by Sears and Conlin gave major insight into the fertilisation of planted tanks, and is an important foundation to the evolution of many, if not all, modern planted tank fertilisation methodologies and theories. However, some of their theories and conclusions in that paper have since been refuted by the same modern methodologies and theories, so read that paper with an open mind.)

    Unfortunately, the term PMDD has been misused to refer to the loose fertilisers that many hobbyists dose separately nowadays. I hope we can stop this on AQ. One, because forums like AQ are good stores of information for the hobby and misuse of terms could lead to mis-information or inaccurate or frustrating information searching. Second, I feel we should respect the work done by these pioneers in the modern planted tank hobby and not misuse terms that refer to key or important outcomes of their efforts.

    I would appreciate it if AQ members will use the term "loose fertilisers" instead of "PMDD" when referring to unmixed feritilisers like KNO3, KH2PO4, etc.

    That is the best term I think of right now. If anybody has a better idea, do post. I have a few more ideas, but I'm uncertain if they are suitable:
    - Elemental fertilisers
    - Chemical fertilisers
    - Inorganic fertilisers

    Thank you.
    Last edited by vinz; 28th Sep 2005 at 14:30.
    Vincent - AQ is for everyone, but not for 'u' and 'mi'.
    Why use punctuation? See what a difference it makes:
    A woman, without her man, is nothing.
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    What you said is true in a way....

    But when we dose loose fertiliser together, it is as good as combining them but in a different ratio than that proposed by Sears and Conlin. So cannot call PMDD?

    What are the terms used in other planted forums? I seldom follow.
    For me, I never used the term PMDD when referring to the way I dose fertilisers in my tank. So not a problem for me.
    koah fong
    Juggler's tanks

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    I'm gulity of this mistake. Hence let "loose fertilisers" refer to KNO3, KH2PO4 and traces. Or "EI ferts" sound more correct, since most who use the above 3 chemicals dose the EI way?

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    But it is not used exclusively for EI. What about the PPS method that is currently one of the popular methods over at APC?

    And we're not talking about those 3 ferts. There are others like epsom salts, calcium nitrate, potassium sulpahte, calcium chloride, and much more.

    Trace mix is trace mix.
    Vincent - AQ is for everyone, but not for 'u' and 'mi'.
    Why use punctuation? See what a difference it makes:
    A woman, without her man, is nothing.
    A woman: without her, man is nothing.

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    Hmmm, "Loose ferts" sounds good. I'll start using that from now on.

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    artifect,

    I split your post to a new thread here.
    Vincent - AQ is for everyone, but not for 'u' and 'mi'.
    Why use punctuation? See what a difference it makes:
    A woman, without her man, is nothing.
    A woman: without her, man is nothing.

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    Quote Originally Posted by vinz
    But it is not used exclusively for EI. What about the PPS method that is currently one of the popular methods over at APC?

    And we're not talking about those 3 ferts. There are others like epsom salts, calcium nitrate, potassium sulpahte, calcium chloride, and much more.

    Trace mix is trace mix.
    PPS still does the basic 3 and if you look at EI, I address CO2, lighting and GH, which deals with Ca, Mg and SO4.

    They both add the _same things_.
    You can use some standard solution or dose the ferts dry, your subtle accuracy improvement will make no difference doing dry dosing vs liquids.

    If you chose either testing or not, you need to make sure the CO2 is in a good range and this is far more difficult and troublesome than any fert routine and far more significant in terms of problems and plant health.

    Regards,
    Tom Barr

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    Quot "
    ...That paper by Sears and Conlin gave major insight into the fertilisation of planted tanks, and is an important foundation to the evolution of many, if not all, modern planted tank fertilisation methodologies and theories."

    I kinda disagree to Vinz's intro here. Before Sears & Conlin there were already other pioneers spear-headed the studies of planted aquarium and developed into commercial products (although pricey). For example founders of Dupla : Kaspar Horst and Horst E. Kipper in their book "The Optimum Auqarium" (I had a copy published in 1985) already introduced undergravel heating, trace elements dosing - the effect of chelated iron to water plant, macro nutrients, and most importantly the use of CO2 gas with closed loop PH controller to promote plant growth ! (In Sinagpore I first learnt the Dupla system way back to 1990).
    But I do agree that Sears & Conlin and many others brought these "commercial secret recipes" into light and with the power of the internet the knowledge had been reaching to the global planted aquarium enthusiasts ever since.

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    Quote Originally Posted by dc88
    Quot "
    ...That paper by Sears and Conlin gave major insight into the fertilisation of planted tanks, and is an important foundation to the evolution of many, if not all, modern planted tank fertilisation methodologies and theories."

    I kinda disagree to Vinz's intro here. Before Sears & Conlin there were already other pioneers spear-headed the studies of planted aquarium and developed into commercial products (although pricey). For example founders of Dupla : Kaspar Horst and Horst E. Kipper in their book "The Optimum Auqarium" (I had a copy published in 1985) already introduced undergravel heating, trace elements dosing - the effect of chelated iron to water plant, macro nutrients, and most importantly the use of CO2 gas with closed loop PH controller to promote plant growth ! (In Sinagpore I first learnt the Dupla system way back to 1990).
    But I do agree that Sears & Conlin and many others brought these "commercial secret recipes" into light and with the power of the internet the knowledge had been reaching to the global planted aquarium enthusiasts ever since.
    Cable heating is Dupla's idea and they can certainly have it right back.
    It's never been shown to help fior the reasons speculated in practical nor any research.

    They never made any macro nutrients(NPK) for many years, it was assumed that fish supply all that's needed. They claim they are responsible for trace dosing, that had been done in the research for a long time prior, same with CO2, they just brought it over to the hobby and charged an arm and leg for their stuff.

    But the main thing they did was bring CO2 into the hobby, not macro nutrient dosing. Soil substrates, hoagland's solution etc have been used as macro sources for 70 years or more.
    PMDD did bring the NO3, K+ dosing to the forefront in an effect to limit PO4 which was assumed to cause algae.

    A mistake that Dupla and many other companies also made.

    I have no idea why they, nor any of the other companies did not try and show that PO4 caused algae or not.

    I added it, I never had algae.
    Looking back at what really was significant and being able to tease apart which elements where significant is relative today.

    But cables, ph controllers, PO4 limitation, NO3 limitation, Fe limitation etc are not particularly useful ideas today........practical experiences quickly tell you this.

    I'm always amazed at how someone can be goign along dosing nutrients with good plant growth, have a 2ppm PO4 level, then when they get algae, they blame the PO4.

    They did not have algae before they had the high PO4.
    But they often only test when something goes wrong, notm leading up to it nor ever induce a possible problem on purpose.

    You never learn causation this way.
    And few of the companies seem to have done this.
    But they don't care so much about that as they do about being a business and making $$.

    Paul and Kevin and myself are not selling you something.



    Regards,
    Tom Barr

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    Hi Tom

    I guess my data on Dupla was wrong then. Thanks for pointing out.

    One question to seek your comment : You brought up the point that the older thoughts on "limiting theory" (PO4, NO3, Fe,...etc) of curbing algae did not hold ground today : as many had experimented high dosing of these and only good plant growth and not algae. What is holding back the algae ? Could it be the strong growthing plants releasing defensive chemical against algae ? Or highly oxygenated water deter alage to set foot ?

    Thanks

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    Quote Originally Posted by dc88 View Post
    Hi Tom

    I guess my data on Dupla was wrong then. Thanks for pointing out.

    One question to seek your comment : You brought up the point that the older thoughts on "limiting theory" (PO4, NO3, Fe,...etc) of curbing algae did not hold ground today : as many had experimented high dosing of these and only good plant growth and not algae. What is holding back the algae ? Could it be the strong growthing plants releasing defensive chemical against algae ? Or highly oxygenated water deter alage to set foot ?

    Thanks
    Wow, old thread, but I get back to things in my own sweet time
    Dupla promoted things ands folks seems to follow them much like ADA loyalist today. At least Amano can scape and take better pictures. But the causes, info being given in technical aspects is even weaker. But that's not Amano's goal, he's there to sell products and make $, same with Dupla. My goal is different.
    I do not point out that you personally are ever wrong, the idea might very well be however. I do not think in such personal attack mode terms I'd have to be a mean old buzzard if so

    So let's see what we can answer for your questions:

    What is holding back the algae ?
    Let's ask "what is preventing the algae spores from germinating, much like seeds? Algae cells do not live that long, they need to produce new vegetative growth and if no adults are growing, new germinating spores.

    So what causes germination is the real question there.
    Is any old time good?
    Probably not.
    Why are they many thousands of algae species?
    Algae have adapted to grow when things are most favorable for them, often in a small short window. They, unlike plants, generally reproduce sexually in aquariums.

    You try and tinker to see what causes algae to bloom, and you do so with a fully planted well run tank(a control tank).So you add lots of light, high CO2, high non limiting nutrients for both plants and algae, then manipulate the single variable of interest, say NH4. Adding say 1.0ppm of NH4 = GW water.
    So next you try this same idea out but this time using progressively overloading the aquarium with fish or shrimp etc all at once. GW.
    Now you go back and see if you can induce GW using NO3, PO4 etc.
    Nope, cannot do it.

    So now you are left with one possible cause(there might be others, but you know what it is not at least for a few things, so you can spend your time testing other fact

    Could it be the strong growthing plants releasing defensive chemical against algae ?

    Nope, Allelopathy was popular when Diana Walstad suggested it and folks still carry on about it. It's very simple for a hobbyists to disprove the idea that this plays any sort of role in aquariums, as well as never been shown in any natural system to play any significant role:

    Add activated carbon to the aquarium/do large frequent, daily water changes etc. This removes those chemicals which are larger organic chemicals which carbon actively binds and removes.

    We see no relationship between Ac use and algae appearances, quite the opposite in many cases. Thus this cannot possibly be the cause. for all the talk and implied baloney, this one is easy to test with rather elegant simplicity.

    I think Diana could have tested this herself in less time it took to write that chapter There's a long list of why and from myself as well as Ole on my web site about this topic. Folks rarely test things when it comes to algae.
    Most are just happy they do not have it and they are not about to test anything. Others are good at rattling on and on, but not doing a thing to test or answer the question, more a peeing match, shouting name calling whine fest

    I think if they spend that much passion, ego and energy, the least they could is test a few things and learn. But I've never meet one yet that has done that.........hope blooms eternal

    Or highly oxygenated water deter alage to set foot ?

    I did this back in 2003, but found the same algae density for several O2 and CO2 combinations. Would have been nice, then we could add O2 gas and kill all the algae

    But what signals do you think might be good telling you that the plants are not there and it's a good time grow for a few weeks?

    NH4, changes in the CO2, more light suddenly, dead bacteria, sudden influxes of these will.

    The other issue is that some appear when the nutrients get too low for the plants, and our lack of care also is a huge factor, so there are social issues as well involved here.

    As light, CO2 and nutrients all play roles, the change of any one that tosses the others out of balance for a time period, say 1 week, is enough to cause algae to appear depending on what went wrong and how long etc.

    I've been reluctant to say specifics about algae in general. More, better to focus on good plant care.

    Why?
    Some things may be multifactorial.
    I can figure out single variable causes in some cases, but under high light, high CO2 and suddenly adding NH4, will induce GW, but not in other systems. Removing the bacteria from a large filter on an established tank might/may do it as well. But if I have a small fish load, lower light, good CO2, then it might not induce algae.

    So there might be more reasons why, more complex than we might assume initially. I answer one question, then I want to know how light and CO2 also impact NH4, and bacteria etc as it relates to algae spore germination.

    There's a lot we are just clueless on.
    Perhaps some will come along and test algae and learn more about it in the future.

    Regards,
    Tom Barr

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    Re: Misuse of "PMDD"

    Quote Originally Posted by dc88 View Post
    Hi Tom

    I guess my data on Dupla was wrong then. Thanks for pointing out.

    One question to seek your comment : You brought up the point that the older thoughts on "limiting theory" (PO4, NO3, Fe,...etc) of curbing algae did not hold ground today : as many had experimented high dosing of these and only good plant growth and not algae. What is holding back the algae ? Could it be the strong growthing plants releasing defensive chemical against algae ? Or highly oxygenated water deter alage to set foot ?

    Thanks
    No, I do not think you are wrong, you are right based on what you knew.

    Growing plants for gardening and horticulture and supplying them with good stable nutrients is different than asking why is algae not present/present.

    I prefer to keep them as separate as possible and look at culturing both of these. To learn how to grow algae, teaches you far more about than simply killing it and doing things you hope make it go away.

    Think about plants if all you wanted to do was kill them?
    Stopping their life cycle, propagules, spores etc is the key to weed control. Algae is no different.

    But people eem to want to/tempted to put algae and plants in the same bowl.

    Rephrase the question, ask: what induces algae to grow?
    Then see if you can cause it to grow consistently.
    If your system is a planted tank, then make sure you have things going well, then raise NO3 up to say 100ppm and observe. Lower it to 80, 60, 40, 20, 10, 5, 2ppm, 0ppm and so on.

    Watch for algae etc.

    The way to do this is while playing with the dependent parameter(say NO3, or PO4,NH4, CO2 etc, light), you get no algae, then you know the other parameters must be independent(thus those are not influencing the results).

    Example, if I have a well run tank, add 2ppm of PO4 and get no algae, regardless of folks who have algae issues, I know that the othe rparameters are independent. The other folks who have algae already, alway have algae etc their tanks are not and never likely where independent , they have some other cause for their algae that's not from high PO4.

    If that theory is true, we should be able to consistently inuce algae.

    However, it's pretty clear this is not the case, so another alternative hypothesis is required and the old PO4 excess = algae must be rejected.

    The issue is that many folks cannot control other parameters well, so tey cannot even test this to begin with. If you cannot rule out other issues, then you will never be able to do the test

    Some folks never do.
    Some do, but only by limiting PO4, which limits CO2, which they have not addressed well, or think they have, but really have not etc.

    Some have strange thinking, insisting that their observations alone are somehow the only observations that matter and are right in the disscusion, I guess the rest of the folks are all lying? Some seem to imply this. However, their theory cannot explain why and how we know and can confirm we add 2-3ppm of PO4 and do not have any algae bloom at all.

    No matter how hard they want to argue and bemoan their points, it will never win the debate, since we know and can test otherwise without such results and have plenty of consistent examples.

    Still, some will never be convinced

    Regards,
    Tom Barr

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