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  • Methods: algae control or growing plants?

    Many dosing methods suggest that they have some way of solving all your algae issues. Curiously, such methods also fail to address algae growth and causes at the root.

    While a method might work to solve the issue of a noxious algal bloom in your aquarium with plants, why it does it, is a matter of debate. Therein lies the crux of myths in the hobby and why I am writing this.

    Control of Algae in Planted Aquaria

    This is a method to address algae in the aquarium.
    However, it is really a method to grow aquatic plants.
    Aquatic plants require 3 main things to grow: light(they suggest enough, however on the low side), CO2, (also on the low side, but error in measurement and low light play a large role there as well as dependency on limiting PO4, which reduces CO2 demand, indirectly stabilizing CO2 availability to plants) and nutrients.

    Since nutrients are LIMITING with PMDD, PO4 specifically, the effects on CO2 are also present. CO2 at 10-15ppm at low light and under strong PO4 limitation will work.

    However, adding PO4 will induce a number of algal species in this system.

    To test whether it is really PO4 limitation that is causing algae to be controlled, we must ensure that CO2 is also not limiting and scaled up when the PO4 concentration is increased.

    Many aquarists see that adding PO4 or allowing it to become higher= algae blooms for their systems, yet cannot explain why other aquarist can have high PO4 without any trace of algae for years, even at low, medium and very high light intensities.

    This reduced CO2 dependency due to strong limitations of nutrients (PO4 is one of the better nutrients to chose), is based on Liebig's Law of the minimum.
    If PO4 is strongly limiting, adding more CO2 will do nothing to enhance the rates of growth. You can add all the CO2 in the world and the plants will not grow more, the PO4 is the bottle neck, not CO2.

    Still, the aquarist who finds management of PO4 = less algae will remain unconvinced, yet have a conflict with other aquarist that have high PO4 and no algae. However, simply because they chose or cannot maintain good higher CO2 along with higher PO4, does not imply they are correct.

    Some people simply do whatever works for them and are resistant to change or learning a new method that addresses balances of light, CO2 and nutrients and scaling up or down depending on light intensity etc.

    There is nothing wrong with that.
    However, to suggest to other hobbyists that it is the cure and the root cause for controlling algae is......well.............very poor logic and even poorer experimental test protocol.

    I suggest hobbyists keep good plant growth and algae in 2 separate groups.
    PMDD address plant growth perhaps more than algae control.
    PPS does something very similar to PMDD, as does Redfield ratio, MCI, and few other methods aimed at controlling algae through nutrients, mostly all of them have one central component: limit PO4.

    What does PO4 limitation do?
    Is it really limiting algae?
    No, not really.

    That metric is extremely low, beyond the limits of test kits and methods used in the hobby. Less than 10 parts per Billion.

    So what is occurring?
    Well, using Liebig's law, we see that PO4 is more strongly limiting than CO2.
    Thus the plants are better able to handle and withstand PO4 limitation, than CO2 limitation. This is a plant issue, not an algae issue.

    We can go back and instead of limiting plants and forcing them to reduce their CO2 demands via PO4 limitation, we can add CO2 at a higher rate and also add more PO4 at a much higher rate. So CO2 and P4 are both non limiting.

    If you only test one side of the coin, you leave yourself open to false conclusions, even if they might work to cure the algae, they do not explain why the algae is gone nor are able to explain why other observations show that high PO4 also does not induce algae.

    So what does induce algae growth?
    This is a different question that how to get rid of algae.
    Very different and specific.

    The answer/s is/are not as nice. They are specific to each and every species of algae. They involve space and time (Ecology), light, CO2........and well as the status of the plants.

    How might we test for algae inducement independent of good plant health?
    1. You must have a reference control. This means a nice well run tank with plants, no algae and non limiting CO2 AND NUTRIENTS. Light can be easily manipulated for PAR and is the growth rate determination when CO2/nutrients are non limiting(up to a point where metabolic growth rates can longer be increased, the maximal yield).

    2. Test light, go from the lowest possible to highest possible PAR. Vary and adjust the duration. Can light manipulation control algae the same way that PO4 limitation can? Certainly and better even. By reducing light intensity, this also reduces CO2 demand(there will be difference depending on how strong of a reduction light or PO4 might be for each case). Still, most aquarist have long noted reducing light intensity "cures algae". Why this is still is based around "Light= drives CO2 demand= drives nutrient demand".

    If you limit nutrients strongly, then adding all the CO2 and light will not change the rates of growth, likewise, if you limit light, then attaining ample CO2 and nutrient is much easier as well, algae also grow slower, since their only limitation is really light intensity.

    3. Test CO2. This is more difficult. CO2 measure is the hardest parameter to come to grips with. By adding good ample known PAR intensity for a plant, and non limiting nutrients, now we can test CO2 effectively. We may also add sediment types to this, both plain sand and enriched soils, to see if sediments play a role or not and to add as a back up for nutrient limitations/preferences within the root zones as well as the water column.

    Since light and nutrients are independent, CO2 is the only dependent variable.
    By adjusting CO2, we can induce and cause germination of dozens of species of algae.

    Only when there is dependence on other variables with PO4 limitation control methods, do we see algae issues(Say adding PO4 to 2-3 ppm).

    This suggest it is CO2, not PO4 that is controlling germination for many algae species. Perhaps.........but it might be due to plants and Carbon uptake that signals algae to start to bloom, not CO2 directly either.

    Still, we know PO4 alone cannot account for algae blooms for all systems and we know we can consistently incduce algae independent of nutrient and light with CO2. We cannot consistently induce algae with varying just the PO4 when other nutrients and CO2, light are independent.

    The only conclusion is that limiting PO4 is not limit algae, rather some other cause must be present. This does that in some planted systems, that limiting PO4 does show a reduction in algae. but that the cause is indirect and related to CO2, not PO4. to test this, we simply add more CO2 and raise the PO4 and we no longer have algae blooms.

    This still does not imply cause that CO2 is the key.
    It is only 1 step closer at getting at the root cause.
    From a management perspective for control of algae, CO2 is central.
    The same is true in a non CO2 aquarium, CO2 stability is key.

    Plants have a rough time adapting to different CO2 levels, algae do not(they are virtually never limited by CO2). Plants need to make a lot more Rubsico to adjust to lower levels, often several times more(10-20X with CO2 enriched vs no CO2) and it takes time for the plant to make these enzymes.

    Changing CO2 around day to day, hour to hour, week to week the plant struggles and spends more energy adapting to CO2, than with growth, acquiring nutrients, catching light etc. In non CO2 systems, changing water frequently causes a spike in high CO2 week to week etc, done only once every few months is better.

    For CO2 enriched tanks(non limiting CO2 systems), changing water has no such impact. The plants do not need to adapt to CO2 since they have ample CO2 and supply for all conditions.

    We may also limit CO2 slightly and PO4 and have somewhat stable systems also, but these are harder to duplicate. Still, plants will adapt moderate levels of CO2 as long as they are stable enough for maintaining the same Rubsico concentration in the tissues.

    So often,m not doing water changes (or as much) in these reduced CO2 systems(like PMDD suggested 10-15ppm) will work well and appear to reduce algae. Still, these systems are still limited by CO2, the plants have adapted, just like the non CO2 systems. As long as the CO2 is stable and does not change/vary much week to week, the plants should still grow well and reduced, but algae free.

    Both of the above curves show that at lower levels, the yields are reduced in the limiting ranges. It is not black and white, they have varying degrees of limitation.
    Mild limitation has less effect on overall growth, while large effects on CO2.
    Very strong limitation has a pronounced effect on growth and deficiencies.

    The adequate and C/B zones give the aquarist the most leeway for dosing, both CO2 and nutrients, as well as light.

    It is only when the CO2(or nutrients, or light) are in the D zones that we can be sure that they are independent when we test the other parameters.

    Tom Barr

  • #2
    Back to algae.

    Perhaps nutrients can play a role?
    I used NH4 and found under high dosing(1-2ppm) and high light, I managed to induce Green water. CO2 reduction also increased the rates of growth for green water(less CO2). GW is common in new aquariums with high light(uncycled tanks, without bacteria and good plant growth, no NH4=> NO3 cycling going on).

    NH4 is the only nutrient I have found to induce GW, also, progressively increasing bioloading to a breaking point where algae bloom also produced a similar effect.
    This suggest that NH4 plays some role. However, others have dosed NH4, as I have as well, and not been able to induce GW or other species. So such results are likely inconclusive. Perhaps poor CO2 played a role and light intensity? Perhaps peat, tannins, sediment types play a role? Some have suggest it also.

    CO2(varying it below non limiting levels) and high light are very consistently however. They can induce many species of algae. Low PO4 also appears to induce GSA. Low CO2: BBA, and staghorn(with high bioloading), BGA appears to be low NO3, but also organic matter.

    Each algae has it's own set of parameters it correlates with. there may also be more than 1 single cause for algae blooms as well. Still testing what will induce algae in an other wise independent system by manipulating one parameter at a time is the best way to see why algae grows and how to stop it. MCI suggest strongly limiting PO4 for a few weeks till you get GSA...then raising it back up and after the other algae has gone away, this will get rid of GSA later. In GW blooms, few other algae species will grow also, so you can use algae and PO4 limitations etc or inducement to control harder to eradicate species also.

    Still, we can do the same eradication with light reduction, or with good CO2 stability. Generally, aquarist find a lot more utility and success watching light and CO2 and of course, the plants. Nutrients are rather easy to dose/add etc. Plants will adapt to lower, higher levels, just like CO2, as long as the inputs are stable.

    Where many go very wrong in their conclusions, is that more nutrients induce algae. This is simply not true. This only occurs when there is dependency on other parameters like CO2.

    While this might ruffle the feathers of the folks who promote such PO4 limiting be told that it cannot be due to limitations directly challenges the claims made, it is what it is, those are the results and cannot be reconciled is terms of the hypothesis : limiting PO4 is what controls algae.

    That is testable and has been falsified. The hypothesis cannot explain how high PO4 does not induce algae. If the hypoithesis is high PO4 = algae, then it should be tested.
    It can be reworded, repackaged any number of ways, but without addressing the light, the CO2 and nutrients independently, the method will still lead many to a wrong conclusion.
    This does not imply limiting PO4 is not a viable option for algae control.
    It is and has been for decades, but why it works has been falsified in terms of limitation of algae.

    Getting at the root causes for germination of algae is a more productive method at control options.
    Now we have more tools available to approach control of algae, not just limiting PO4.
    Increased CO2, reduced light intensity, better current, better filter cleaning, keeping biomass the same etc, adding liquid carbon supplements in conjunction, water changes(or reduction of them), reconciling why various methods work in a holistic approach to plant growth including non CO2 methods. This also allows us to test better and look for more causes rather than putting all of our "eggs in the *nutrient* basket". That is risky.

    In terms of management, we need a hypothesis that addresses several methods, several seemingly contradictory observations, and that explains why it works for each method chosen by the aquarist.
    This gives us the best explanation, the most tools and makes the most sense. It also helps us to focus on plant growth, then when algae does come along, we know what each species is a bioindicator, or a "test kit" of.
    This makes management easier as well for algae and plant growth.

    Tom Barr


    • #3

      Suggest no relationships between natural lakes and aquatic plants and nutrients, thus it appears to be some other mechanism besides just limiting PO4(eg CO2 and light, actual starting state of the lake).

      Regarding ratios and the RR(Redfield ratio):
      This statement is from Anderson's "Algal culturing methods" text(2005):

      The RR "is arguably one of the most abused parameters in the field of aquatic ecology. the RR is an approximation of of a composition averaged over very large scales of time and space and does not describe the conditions of individual cells and populations".

      Anderson goes on the cite several chemostat studies where the ratio for the freshwater Scenedesmus was 30 N:1 P, nearly 2 fold difference, 25 to 33 for a diatom, Pavlova , 35-40 for the diatom Chaetoceros. It is expected and does vary with irradiance(light.

      So light, the species in question, all make a huge difference in these limitations and ratios, particularly when they ARE APPLIED TO ALGAE. Even so, using RR and increasing the concentrations 5-10 fold on both sides of the ratio will ensure the algae is not limited by either nutrient.

      Anderson suggest that unless carbon limitation is a goal, air bubbling will suffice for Carbon supply.

      Many studies support the CO2 compensation points for algae are in the 0.1ppm ranges for the higher green freshwater algae species. Here is a review of 16 freshwater species:

      Measurement of Carbon Dioxide Compensation Points of Freshwater Algae -- Birmingham and Colman 64 (5): 892 -- PLANT PHYSIOLOGY
      Photosynthesis and Photorespiration in Algae -- Lloyd et al. 59 (5): 936 -- PLANT PHYSIOLOGY
      Measurement of Photorespiration in Algae -- Birmingham et al. 69 (1): 259 -- PLANT PHYSIOLOGY

      22 ppm of CO2 is = about 0.5milliMoles of CO2.
      The above ranges for algae are less 2ppm for all.
      Most are less than 1ppm, amd some are down in the 0.1ppm ranges.

      Compared to plants which saturate at 20-30ppm for aggressive aquatic weeds with excellent aggressive CO2 and Bicarbonate uptake mechanism (this is why they are so competitive and aggressive):

      .5 to .6 mM of CO2 was the maximum CO2 range at high light for these easy to grow weeds. More CO2 was required at lower pH since these plants can and do use Bicarbonate as a source of carbon.

      If you look at figure 6, you can see how much more aggressive Hydrilla and coon tail are compared to Cabomba and Milfoil. These species have different abilities to utilize light and CO2.

      Aquairst assume thast all aquatic plants are equal when it comes to adding enough CO2. Clearly there are demonstrated differences in the research and within the aggressive noxious weeds which are better at acquiring CO2 than say HC or other aquatic plants, of which there are 300-400 species. surly they cannot all be aggressive noxious weeds with the same abilities to take up CO2 from solutions of use bicarbonates as a source of DIC.

      Algae are wide in their ranges and nutrient, CO2 and light demands as well.
      The points here are that we should very careful when generalizing what is a limitation, how important a ratio is/is not, and what other affects such as KH(higher pH's in the above study using NaCO3) and the ability to use HCO3.

      It is no secret why I have had few issues growing every species of aquatic plant to a high level and resolved algae issues effectively.

      I ensure there's ample CO2 for plants, above and beyond the minimums set in such papers referenced above, perhaps 30ppm of CO2 is too low even for some species, while plenty of other species. Hard to say without doing the research on those specific species in question. With 300 or more species to test, that's a lot of research yet to be done. Rather than that approach, adding excess levels that ensure all species have ample CO2 seems a better management approach.
      While we may be curious as to the CO2 compensation points of the various plants, we in general, just want to know how much to add to ensure we are not CO2 limited.

      The other issue is getting at the root cause for the algae germination bloom.
      We can kill algae many different ways and remove it, nutrients, CO2, limiting light etc, chemical treatments etc..........but prevention is wiser than a pound of cure.

      That is the key and it is focused on the plant's growth and health.
      Plants, not nutrients define and maintain the system when they are in ample supply.

      Same is true in many other fields wit pest, farms etc, weeds do not get established and become an issue unless poor management is done and poor crop health occurs.

      Algae are also sexual and have many asexual stages in aquatic systems that our plants simply do not have available, this allows the algae to survive brutal environments and high and low nutrients, light, and CO2 levels. Understanding what those signals that cause algae to go into these stages is key to stopping their continuing growth. Adult algae tend to be short lived, so if you stop new growth and stop these cycles, you stop algae.

      As long as you can grow aquatic plants still while treating algae, then the method should work well(nutrients, CO2 or light or a combo of the 3, or chemicals etc).

      Tom Barr


      • #4
        Thanks for putting that together Tom, it is a good read and very helpful.
        6' Planted Tank (72" x 18" x 20") - 4 x 30W T8 Tri-Phosphors - 2 x Eheim 2217 'Classic' canisters
        Flourite substrate - Ocean Runner OR-2500 + AM1000 - Tunze Turbelle Nanostream 6045
        6.8kg Catalina CO2 - Red Sea Pro regulator - Swagelok B-SS4-A metering valve - Vecton 600 UV


        • #5
          Very good article en very helpful. Thanks.
          Last edited by dutchy; 08-27-2009, 09:59 AM.

          My 2011, 2012 and 2013 AGA aquascaping contest entries:


          • #6
            thanks for sharing, this is a very insightful read


            • #7
              Well folks seem to miss that algae control is a different metric than growing plants.

              Many seem to think it is algae control when they manipulate plant growth demands directly. Clearly, it is not when you strongly limit PO4, which all these methods do. The effect of limiting PO4 is a strong reduction in CO2 demand of the plants(this has no effect on algae, they are not limited in any of these cases for CO2/nutrients, only light might be the only limiting factor for their growth rates).

              When you grow the plants well, whether it's indirect via nutrient limitation of PO4(GSA is a better trade off than say BBA, or hair algae), or direct via good CO2 and non limiting nutrients, you can tell right away that (Having done both for many years myself at least) it's about the plants really.

              Not algae, that's an indirect consequence of reduced/eliminated CO2 limitation in plants, it has very little to do with algae in and of itself. That is not to say/imply the methods will not get rid of the algae you have. However, the methods miss the point about why it works and what about algae and CO2 that can be inferred. You also must be able to test the algae at the log phase of growth, this is the accepted way to make sure all test on the alga of interest are equal, not some 1/2 dead alga that was close to death. Only the most healthy fast growing algae is tested for a control/inhibition methods.

              This is common sense, so you need to know how to grow and induce algae to that stage, if not, you cannot say much about it.

              Unless you can master both methods, you will never see clearly(this applies to EI users as well, not PMDD users etc) on this. We all know that both methods can and do work. T%hose are the observations(not support for why each of the methods work-some like to imply this )

              Years ago......... I thought as did many folks in our group, and on the APD...... that GSA was just a fact of life plant aquarist could likely not escape. I noticed I had less of it than many(better CO2, more PO4) but I could not get rid of all of it.
              Pissed me off, if I had one algae I could get rid of, that would be GSA.

              Stephan from Malta suggested on the APD about using H3PO4 acid as a way to kill off the GSA on his Anubias, it worked. A number of folks added KH2PO4 and found a similar pattern. Plants did not demand so much PO4 clearly, based on uptake or demands, but the CO2 and pearling also increased.

              Now there was no more GSA or any species.
              This was not a limiting solution, rather, the method was a non limiting solution.

              Therefore, it could NOT be due to limiting algae and controlling algae this way, it was due to enhanced growth and balancing Carbon demand in the plants.
              Pretty damn big difference if you ask me.

              Tom Barr


              • #8
                Hi Tom, greetings from Mexico...

                I have just read this tread and I find it so rigt, and I was wondering if you have ever read about the method of controlled imbalances? It's a post from DrPez forum and has a long time ago beein accepted in there, ii based on a, so called, generic protocl of KNO3, which consist in adding as much KNO3 as is needed to get GSA to control almost any other algae, and it has being used as a way to fertilize any aquarium...

                Here is some discussion in APC about this with a good acceptance:

                And here is the original post in DrPez: Dr. Pez - Panel de Mensajes - (debate)Propuesta de método de control de algas + fertilizado

                What do you have to say about it? (almost everything seems clear in your tread but I want your review if it can be possible.)

                Genaro Mendoza


                • #9
                  Originally posted by gdevil View Post
                  Hi Tom, greetings from Mexico...

                  I have just read this tread and I find it so rigt, and I was wondering if you have ever read about the method of controlled imbalances? It's a post from DrPez forum and has a long time ago beein accepted in there, ii based on a, so called, generic protocl of KNO3, which consist in adding as much KNO3 as is needed to get GSA to control almost any other algae, and it has being used as a way to fertilize any aquarium...
                  Yes, a fellow forum poster here suggested it some months ago.
                  I posted a few comments there.

                  By adding lots of N, you drive the P down to near zero, which is why you get GSA......................

                  Same with using PMDD, and using other methods that are similar like PPS, all these methods drive PO4 way down to limiting levels for plant growth.

                  MCI can use any number of of methods once the algae is "gone", and shows that high NO3 are not a cause of algae or detrimental to fish. However, if you think about algae, this same approach is and can be used for light, simply modifying things for a temporary time frame, then once the algae bloom is gone, resume the old dosing method.

                  CO2 also works.

                  Light and CO2 seem to be/are the root issues and causes for algae, not nutrients, however, the effect of strong nutrient limitations will impact CO2/light.

                  I do not think they really wanted to hear that fact. It's based on Liebig's law of the Minimum. Why more hobbyists do not focus on this law is beyond me.:eyeroll:
                  The other issue is they suggest merely because it works to control algae, that that is proof of the method. While it does get rid of algae, the same can and has been said of PMDD.
                  It does not prove what caused algae, that it is/is not the best management practice.

                  Strong limitation to plants by PO4 has no strong negative effect on plants other than reduced growth rates.

                  However, this does not say why the algae came about in the first place. Nor what effects it may have on CO2 demand.
                  If the CO2 was limiting to start with, then you had issues with CO2, not nutrients........they did not test this.
                  Nor test any other alternatives, so it's not a guarantee or "proof" that the algae came about because you had high PO4.
                  They also seem to admit that high PO4 in some aquariums are fine, but not in others and cannot explain why curiously.
                  You cannot have this both ways.
                  There are other factors that become influenced by strong limitation, factors like CO2, and light that where not tested.
                  Liebig's law keeps coming up and how you have simply traded one limiting factor(Say CO2) for another(say PO4) to manage nutrients, instead of focusing on plant growth and getting at the root issue(CO2 in most/many cases).
                  Perhaps for many, managing nutrients is easier that address good CO2. They simply cannot for whatever reason, manage the CO2 well enough. I can get rid of every type of algae with CO2, or light, or nutrients(using pretty much this same method, 10 years before). My interest is not what gets rid of algae, that is simple; good plant growth and an ounce of prevention is worth a pound of cure.

                  My interest are in what causes algae to bloom.
                  How to grow plants is easy.
                  Why algae grows is a much harder question.

                  I no longer go to APC after a falling out with their mods and owner. Too many rats and personal BS. They have a new owner, I understand, but I really do not care. I have other things to do.

                  And here is the original post in DrPez: Dr. Pez - Panel de Mensajes - (debate)Propuesta de método de control de algas + fertilizado

                  What do you have to say about it? (almost everything seems clear in your tread but I want your review if it can be possible.)

                  Genaro Mendoza
                  Yes, I read it. It works, but takes time, experience, and careful watching of the tank while you end up with GSA.

                  PMDD achieved the same thing, however was more conservative, but also had less light intensity.

                  Many thought GSA was not an algae we could get rid of.
                  Both myself, Steve, a few others on the APD, and particularly credit goes to Stephen from Malta for GSA and high PO4 control. So once you got to that point, which many aquarist had, we added more PO4 and the tanks looked awesome again.

                  Now new algae blooms do not occur and have not for months on end, and years.................using higher levels of nutrients, N and P, Fe, Ca etc, these can be all over the place and never get any algae.

                  Why is that?

                  These methods come along and claim to know what controls algae, which is complete BS. They are telling you what want to hear, not the reality.
                  Perhaps they honestly believe their own BS?
                  I think many do.

                  However, they do not test the alternatives(this is a key factor in seeing if they are full of BS and have done their homework or not).

                  You have to test other alternatives and try and disprove your own hypothesis. Instead, most try to look for facts to support their conclusions, not disprove it.
                  I have changed my hypothesis according to what I have been able to disprove.

                  I once thought algae was limited by PO4.
                  So I tested it.
                  I rejected that notion.
                  I tried NO3, I tried Fe, then I started working with CO2 and light more.

                  CO2 is central to everything where aquatic plants are concerned, and the effects on algae are indirect, as algae are neither CO2 nor nutrient limited.

                  We all know this: when plants are growing well, algae does not.
                  So why might we get an algae bloom then?
                  Because the plants are not growing as well as we might think.

                  I've kept nutrients stable and at high levels in sediemtns and the water column, used low, medium and high light and measured the light in the tank through time.
                  The only "nutrient" variable was CO2 and it has massive effects on plants first, then algae blooms are secondary.

                  Carbon status of the plants appears to control algae indirectly.
                  Because nutrients where independent in these cases, no algae was present before and after returning the CO2 to prior state, no algae appeared and what was there died off, this demonstrates that nutrients are independent.

                  Thus we cannot conclude that algae blooms are limited by nutrients, rather, that the alternative hypothesis must be put forth.

                  Perhaps CO2 and carbon status of the plants.
                  Light drives the rates of CO2 demand/uptake and status.
                  So reduction in intensity of light will and sure enough......does reduce the algae and effects of CO2 demand/nutrient demand.

                  This more global view of how plants grow means better longer term management using not just nutrients, rather, all the elements that drive plant and algae growth(Light, CO2 and nutrients).

                  CO2 is influenced by many things, it's not as simple as many like to suggest on plant forums.

                  Nutrients are much easier to rule out independently.

                  I'm not saying that MCI is not a viable option to get rid of some green algae, BBA perhaps etc, but that's not why those algae are there to begin with.
                  It (the results) do not answer the other parameter issues like was CO2 a dependent factor?

                  Without testing that, you leave your pants down.
                  I think some revisions could make the approach better and not try and say more than the results honestly suggest. Then a more effective tool would be focusing on all the elements for management of plant growth, not just a nutrient scheme.

                  EI is a minor player in the overall scheme of plant management.
                  CO2 is huge and light is huge.

                  the other issue is how to reconcile this with non CO2 methods, the hypothesis on Carbon I suggested along with light do explain why those systems also work, and also why they work regardless of ratios, regardless of Ca and PO4 ratios etc.

                  I have aquariums with extremely hard tap, very soft tap, our SBFAAPS club had a very very wide range of tap water types to compare to in person.

                  This ratio business is poor and misapplied typically.
                  Mineral nutrition plant scientist also do not buy into it much either(Eg Epstien, Bloom). Those guys know more than I will ever know.
                  I'll defer to them.

                  Also, to simple practical experience moving around and using very different tap water sources and dosing. It's virtually always a CO2 issue at some level or not enough nutrients. Light drives this rate.

                  It is going to be difficult to escape this no matter how well worded the arguments and distractions will be.

                  Tom Barr


                  • #10
                    Originally posted by gdevil View Post
                    Hi Tom, greetings from Mexico...
                    Genaro Mendoza
                    What part of Mexico?
                    I use to Live in Cuernavaca, Morelos.
                    Been 28 years however.

                    Tom Barr


                    • #11
                      Tom, I've got a question that's been bothering me about CO2.

                      Do fluctuating CO2 levels within non-limiting parameters cause any algae or plant growth issues?

                      And one other question, is there a certain correlation of ideal PAR to PPM CO2 that seems to hold true in a semi-controlled environment? Say a mat of HC laid out under varying levels of PAR and CO2?

                      - Dan


                      • #12
                        Originally posted by Philosophos View Post

                        Do fluctuating CO2 levels within non-limiting parameters cause any algae or plant growth issues?
                        No, this plays no role once a good stable adaption to non limit values has been met. That's the point => non limiting values are say 30 ppm and above for Milfoil, then whether they are 40, 60, 100ppm, as long as there is no issue with fish or bacteria etc, then it does not matter.

                        This same graph applies for CO2, as it does for NO3, or PO4 or any nutrient:

                        You can see that the "D" range is huge, very easy target to hit.
                        C less so, B even harder, going to A is pretty easy, just try and remove as much as you can by adding everything else to excess ppm's.

                        D can be anywhere form say 30-200ppm. where as C might be 22 ppm to 28ppm etc. B might be 15-20, A might be 0-12 ppm etc for a given light intensity.

                        With less light intensity, these numbers shall change:
                        D will now be say 18ppm to 200ppm.
                        C will be 12-18 ppm
                        B 7-12ppm
                        A less than 7 ppm etc.

                        As you can see, the management with less light intensity will be greater and your effective non limiting range has now increased.

                        This is not just true with aquatic plants, but is a light relationship that is true with all plants grown under different light intensity. The process is biochemically driven by light. More light, the higher the ranges shall be and the less wiggle room.

                        And one other question, is there a certain correlation of ideal PAR to PPM CO2 that seems to hold true in a semi-controlled environment? Say a mat of HC laid out under varying levels of PAR and CO2?

                        Yes, I'd say so, but given all the CO2 factors, current, filter, flow patterns, other hardscape things in the water, type pf other plants present, their biomass, the effective flow rate through the CO2 reactor etc..................CO2 is a difficult parameter to nail down without some sort of accurate probe we can measure right at the plant in question for light, O2, and CO2.

                        They have specific machines made by LiCOR that do this for terrestrial plants, but not aquatics. A modified chamber could be made for aquatic plants and a leaf are index could be taken etc and scaled for each species.

                        Lot of work, you got the grant money? I'll do it

                        I'd guess, and this is a 50micrmol of light for 10 hours, a non limiting amount would be 25ppm CO2 [aq]. Pretty high for a lower intensity of light. Many have 70-120 and complain that they have no HC growth, so it might be 40ppm is required.

                        At these higher rates of CO2, it becomes harder to keep fish due to O2/CO2 respiration for both of these gases.

                        So you have less wiggle room and more CO2 stress to fish with higher lighting intensities. Wiser to be patient and let the plants grow a bit slower, have healthier fish, muc more managable CO2 and stability.

                        Then the aquarium is easy to care for/dose and CO2 is also much more stbale.
                        Such aquariums have far less algae issues.

                        Then you do not need "methods of algae control" , as I said and have always said since first posting back in the mid 1990's, focus on plants, not algae.
                        An ounce of prevention is worth a pound of cure.

                        But many add too much light, then whine about CO2, or think they have good CO2, then limit PO4 and think that nutrients are the "key". All these different methods arise from these misconceptions and the real picture is clouded.

                        If you want to study algae, then do specifically that.
                        I did and it proved very successful and accurate.
                        If you want to study plants and growth, then focus on their needs.

                        People screw up the plants, then look to blame algae.
                        Not themselves or their own assumptions.
                        The evidence is there, the research that explains it is also there.

                        Hobbyist often just do not get it. Researchers have for a long time.
                        Ole, Troels and myself had this conservation some months ago when they came to the AGA and I took them all over. We talked about 15 minutes about aquatic plants over 3 days. The rest was about how "normal: 2 meter Troels looked next to a Redwood tree or the various macro algae in tidepools here.

                        I rewrite and try to explain it again and again and again.
                        Maybe if I say it enough it will sink in?

                        Tom Barr


                        • #13
                          Also , you may want to(should) review the article written by Troels, ole and Claus on light and CO2 on Tropica;'s web site.


                          "The exact amount CO2 may always be discussed but if you do not have very sensitive fishes in your fish stock, concentrations from 25 and up to 50 mg/l will only improve plant growth. You will probably see that plants, which were barely able to survive before now, thrive in the presence of CO2. "

                          Excellent review on aquarium plants on CO2 and light and how they interact together.

                          Light was independent, then they tested CO2 independently.
                          Nutrients where independent throughout the test.

                          This is a much higher suggestion than the old PMDD and some of the PPS crowd, going with 10-15ppm, but no light PAR measurements. Talk about testing, but then not test light too? Limiting PO4 but not discussing Liebig's law of the minimum?

                          Plants are not just one element, you need to consider the dependent effects when one thing is done, how it affects the other parameters. Tropica has done that. The focus there is on plant growth/how why plants grow.

                          Not limiting algae.

                          ADA likes to play both side of the coin, suggesting that there are excess nutrients that are causing algae if you do not follow their suggestions or routines(they occur even if you do not) so they play to the myths.............but they also add a lot of ferts in the start of the aquarium, far beyond the minimum needed in their sediments which are very rich, and the light is much less intense that what we might predict when tested with a PAR meter.

                          Still, they have low light, plenty of nutrients in the sediment and a lot in the beginning in the water column via leaching. Many have few issues even with high nutrients using ADA also.

                          Some do.

                          Still, less light will be easier to manage for both nutrients and CO2.
                          So even if a limiting PO4 approach is done for plants, the lower light and better focus on CO2 will help.

                          Tom Barr


                          • #14
                            Tom, the article you linked to shows some things that I've found true just observing your advice. It's a great read for the basics of understanding CO/light relationships, and it's an external source that corroborates what you've been saying for a while now.

                            In my own experience, BBA definitely sets in when my drop checker, shows a CO2 level of ~20ppm +/-10ppm vs. a definite 6.6-6.4pH. In my last batch of ferts, I was playing with NO3/PO4 limitation to push red; I got GSA and bronzing.

                            Perhaps the old view was a more acceptable alternative; 10-15ppm CO2 with a little GSA sure wouldn't be as bad as the 2.5-10ppm of DIY CO2 without PO4 limitation to allow a more even competition. It sure isn't as favorable compared to what you've come up with, but I can see where the mind set might have come from. Many hobbyists are cautious with adding more of anything; human added variables of any kind seem to get the same reaction as the dark ages in Europe gave to the sinful nature of humans.

                            As for ADA, well... I've vented plenty on that one. I'd respect them more if Amano would hop on one of our forums and engage in debate like Greg Morin did once upon a time.

                            - Dan


                            • #15
                              Originally posted by Tom Barr View Post
                              What part of Mexico?
                              I use to Live in Cuernavaca, Morelos.
                              Been 28 years however.

                              Tom Barr
                              I'm from Apatzingan Michoacan, Cuernavaca it's a great city, hope you have some good memories from there.... sorry for te OT.

                              thanks for the great answer about my question, it was very usefull, and also the thing about de CO2 and the light was something I've been worring about since I use DIY CO2, and the variation sometimes it's dificult to control...

                              Genaro Mendoza