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N and P and C

Discussion in 'General Plant Topics' started by Tom Barr, Mar 13, 2008.

  1. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    Hi, this is a thread about N, P and C that's been moved here.

    [Naman Quote]
  2. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    Haha, more than you know!
    I learned about people before I learned about plants.........

    I suggest folks to use LESS light, you will see me do this many times.
    That saves them from most of the issues, and many report much better results with using less light, generally in the 2-2.5 w/gal range or less.

    This includes several clients as well.
    They all started out with lots of light and now use a fraction of it.
    This is a very common theme going back 15 years.

    Then, if the neglect the tank, they have much less trouble and lot more time before it really goes down hill.
    If the person knows they tend to neglect tanks, then a non CO2 approach is very suitable.

    So there are options that meet everyone's goals here.

    Low light/CO2
    Med light/CO2
    High light/CO2
    Low light/Excel
    Low light/non CO2

    This gives people a number of choices all of which are easy to mange and increase the rates of growth to match their goals.
    They all successfully grow plants, but at different rates of growth.

    When we afraid of algae and dose less and less (beginners case).
    When we missed several doses (no time, no new ferts, when we have algae because of NH4 etc).
    When we dose less ferts when have problems with stunted plants and do no know why exactly (low Mg, Ca, Fe, K etc)
    When we have algae because of low CO2 (bad reactor, dirty reactor, low bubble rates, exhausted east solution etc)

    Every time we have algae, regardless of the reasons.
    We always dose less nutrients as dosing more in such situations will feed algae.
    We start to do massive water changes.
    This way we reduce nutrients base for algae, reduce NH4+ and build up of organics.
    Unfortunately this substantially lowers CO2 concentration too and starve plants on P and N.
    Here you have a period when plants are… limited on nutrients.
    (Note: sure this does not the case when we have rich substrate)

    What will be the case if algae appeared because of low CO2?

    Again we do massive water changes, and do less water column dosing.
    Plants become limited. Algae are not.

    Does it make any sense to allow for plants to have more N left in internal buffer and a little bit more N “leftovers” in water column? Yes.
    Does it make sense to have less P in water column to have less algae biomass in this period? Yes.

    If you have lack of CO2 plants will quickly run out of N and will not use lower CO2 levels = will not grow. Why?
    When you constantly dose 1:5 plants have low N buffer (having lots of CO2 and enough light they use those non limiting P levels for growth really exhausting N). Plus you have much more P build up in case of problems and more P left for algae.
    When you dose more N than P (as says Redfield ratio) pants will have large internal N-buffer and easily overcome those two-three weeks of inconsistent dosing of ferts and/or low CO2 due to low bubble rates or during massive water changes while eradicating algae. When they ARE limited. Isn’t that? (fix me about how long they can live on internal N and P buffer, plz)

    So, is it wiser to allow plants to have more internal buffer on N and left N in water column after massive WC’s? Yes.
    While you consistent with dosing there is no sense in P:N ratio.
    I am talking NOT about situation when everything is OK and P:N ratio really has no matter, but about cases when algae becomes a problem and we DO limiting our plants being Not consistent.

    Is it good habit to say dose more N than P? I do not think so. I do not have evidence to show that it is in planted systems.
    This will NOT harm, NEVER, but will help to overcome problems “when plants are limited” while you have not consistent dosing regimen, low CO2 etc.

    Naman, you are hung up on the issue that algae are P limited in our tanks, they simply are not and this has never been shown to be the case, ever,.
    I've done enough aquarium algae experiments in my day to know this is not correct.

    This is the flaw in all of this.
    This is also what was claimed about 12-13 years ago by Paul Sears, he was wrong and knew it after we showed more and more evidence.

    Algae are never nutrient limited in a plants fish aquarium.
    They never have been.

    They grow and appear for other reasons, not because they are limited.
    By limiting the plants further with PO4 chemical removers, you only stress the plants further, the algae will slow some, but they are not going to be beaten, and it will be at the expense of plant growth.

    When nutrients get low, plants will suffer more in terms of growth rate than algae ever will.
    This is common research knowledge in marine and freshwater limnology, aquatic science.
    The smaller the organism, the less it's nutrient demand.
    This is true across the biological world.

    This does not just apply to aquariums.

    And, importantly....... less plant growth as well.
    You hurt the growth rate of the plants more than the algae, thus provide more competitive advantage to the algae, not the plants.
    Algae are much better adapted to grow a lower levels than plants.
    The same is true for marine macro algae/marine plants and micro algae.

    The ratio has nothing to do with it though.
    It never did.

    This is completely about limiting ranges, you cannot bounce back and forth, or use a revolving door with ratios and limitations.

    You have a limited system for plants, poor cO2, poor dosing.
    Then you want to move into a PO4 limited system for plants(1st), then say that the algae are PO4 limited.

    You need to sit down and think about this more.

    Pick one situation at a time.
    Not both.

    The plants are limited with CO2, with dosing(many possible variables here) and now PO4 limitation.

    I'm not clear why you think this "method" is the least bit useful to anyone?
    It does not focus on the needs of the plants.

    Any method that ignores that to prevent algae is a poor method by any horticultural standard.
    It clearly gives the advanatage to the algae and pest, not to the plants.

    Something tells me measuring CO2 is the main problem here.
    I have trouble and adding peat and other acids or non carbonate buffers make the rror ranges very high here, at least 10ppm either way.
    When I recently used a special CO2 meter using non pH/KH measures, I was off by 7 ppm even with the best pH and KH measurement methods.

    So I know other folks, hobbyists are way off.
    Eye balling CO2 seems to be about the best method with a really good meter.
    And if that is not accounted for, then the results really are not what they are claimed.

    Also, you make a very bad assumption here, PO4 is not locked up in the sediment.
    Plants leach and export PO4 right out of the sediment.
    Please review Barko et al.
    The nutrients in sediments are actively exported out of the sediment to rather high levels that make algae growth far far from anything remotely limiting.
    P32 studies have shown this numerous times.

    We have done this at the lab where I work.

    It depends on the questions asked.
    If the critical P level is too low, then plant growth is definitely affected.
    Then you have a situation where the plant growth is limited and the algae not.

    The better studies I've read showed this clearly in the Everglades. It is the most researched aquatic plant periphyton algae region in the world.

    The South Florida Water Management District(SFWMD), found that aquatic plants where effective for PO4 removal to about 50 to 20ppb, that's it.
    They did not stop even below 20ppb even at 3-10ppb.
    You really cannot do detection monitoring below 10ppb and have a good error range in your measurements.
    That's at the best possible research methods and labs money can buy basically.

    I've talked to the lead principle researchers there.
    They gave a nice talk at the UF.
    I grilled them but they knew far more than I about ranges and hard data.
    They had every answer for any thing I threw at them.

    That's research I know I can trust.

    No, it applies when you reach that critical P or N level, the ratio does not matter until then.

    I think you need to talk to Ole in person.
    I know him and we have talked about such things and quickly agreed.

    And we(Troels and Claus as well) also agreed that aquarist misunderstand and misapply concepts, principles and interptations, the researchers all get and understand it.
    We get the relationships, aquarist that do not, make a big stink over it.
  3. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    There's not advantage, even Amano himself will tell you otherwise.
    Amano, Ole, myself, Claus, Randall, Oliver et al, will all tell you to focus on the needs of the plants.

    That, not trying to unwit algae is the path.
    We all say the same things from very different backgrounds and approaches.
    What are the odds, we are all wrong and you are correct?
    I asked myself that question long ago when I challenged Paul Sears, but I was right.

    You have less issues with algae because the dosing issue is addressed by adding ferts to the sediment, NOT because algae are limited or some ratio of N and P.
    If you forget to dose the water column, you have a back up in the sediment.

    Does not matter where plants get the nutrients, as long as some is there somewhere they can get at it.
    Algae are not limited, but they do grow when the plants do not, the plants act as a substrate for algae when they are not actively growing and they also stop taking up NH4 and less CO2 if they are limited via N, P, Fe, K etc.

    I do agree adding sediment based nutrients as well as water column dosing provides more stable conditions lest the aquarist forgets to dose.

    I've been telling folks this for many years, and very much so now that the ADA aqua soil is widely available and much more consistent and less messy than "mud" or "soils".

    The two methods go hand in hand.

    It has nothing to do with a ratio or limiting PO4, because I've been using ADA AS + EI for several years.

    Here's some results:


    Sure, why not?
    Because you are not limiting algae or plants in either case............

    You are using the "either ... or" argument and not seeing the bigger picture here.
    Plants and algae are both opportunistic.
    Plants are much more likely to be limited and then the system is more algae prone.
    Both algae and plants get nutrients from both locations, any slight diffusion across the sediment, any transport by plants up and out of the sediment, any fish waste generated, all are available to the algae and far far from limiting in any way.

    No it's not.
    The reasons they claim why are different.
    Ole will tell you different as well if you go speak with him about it.

    In EI with plain sand and in an ADA system with light water column ferts and rich sediment, both tanks are non limiting for plants.

    ADA has nutrients available in both locations. In a sense, so does EI, but if you take EI+ ADA sediments, now you have plenty of nutrients in both location and less issues with algae.

    Plants do not care, they just need some source of nutrients, it really does not matter where that much.

    Do not worry, you will understand this some day:)
    But work through it in your mind.

    Well, the sediments are not different, just the water column, and we generally dose after the water change anyway. Water changes tend to add CO2, clean the leaves, improve exchange and you see the growth effects on plants afterwards in most cases.

    You seem stuck on the CO2 issue, but it's light dependent.
    This tank mis fine with 15ppm, it only has 1.5 w/gal and gets no water column fertilization, neither did several of my tanks, just fish food:


    I asked Steve to add EI and the tank just grew faster was all.

    In the tank's above, you need more CO2 because you have more light.
    If you want less CO2, use less light, this is just plain common sense.
    More light = more growth rate= more CO2 demand.

    I really question the measure of CO2 as well.
    Especially in tannin/peat based sediments like ADA.

    With the new CO2 meter, I was off by over 8 ppm. that was with the best KH references and pH meter and with massive RO water changes to reduce KH errors.

    Now if I'm off that much, what are the odds others are as well?
    Pretty high.

    But why would you reduce the CO2 in the first place?
    What does that gain you?


    Reducing the light gains you less nutrient demand, less CO2 demand and virtually every thing is slowed down and more stable.

    What is more stable/safer/easier for people, driving at 150 km/h or at 40 km/h?
    Which uses less gasoline?
    Which speed is better if you crash?

    Same thing with light.

    No, using sediment ferts with EI will.
    The ratio has nothing to do with it.
    It's only when you neglect.
    And... the sediment ferts makes up for that much easier than any water column ratio.

    It's only when you stop taking care of the plants (not take care of their needs), use too much light, let the ratios become limiting and if you do not use sediment based ferts as well.

    That's not a good method.

    True, but I'm saying the sediments, not the ratio or limiting PO4 is the reason.
    Big difference.

    And the solution is to use EI+ ADA AS.

    Tom Barr
  4. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    If the real goal is error on the side of safety, then a non CO2 approach with low light and a rich sediment would be even wiser.

    This takes out CO2 entirely, as well as higher light.
    It takes out any need for water changes essentially forever.
    It takes out any real need for water column dosing.

    However, such tanks can still get algae even with no PO4 added at all.
    Fish waste and food obvious supply some input.

    The same concept is true when you add CO2.
    Fish waste will never allow the algae to be limited, unless you just do not keep fish, then it's not much of a hobby:cool:

    Still, if that is your ultimate goal, then that method is by far, much more superior to ADA's, cost less and takes less work.

    You need more time and patience, but the method does indeed work well.
    By your logic here, ADA has it all wrong, and non CO2 is the way to go.

    Why would 15 ppm vs 25ppm be an issue?
    Neither range is detrimental to livestock.
    Nor is one harder than the other to target.
    You just add a bit more is all.

    Lowering it and showing that it's really 15ppm and it stays 15 ppm over the entire day(say to within 2ppm of CO2) is difficult even for me. I have a 2000$ CO2 meter that can do it. But there's no way I can really do this with such equipment, I doubt any hobbyist can either.

    Since I target non limiting levels, the upper ranges beyond the ppm's I chose are much easier to target.

    So less light, rather than trying to manipulate CO2 and nutrients, which are far harder to consistently maintain, is a much easier method to control rates of growth and prevent trouble.

    I really do not want the slow growth of non CO2 methods for most of my tanks, if I had 20 tanks, yes, that'd be too much work.

    But for the 4 tanks I have that I add CO2 to, I change the light, so does Amano.

    I'm sure he can drive the growth faster, but it's easier for other people and hobbyists to deal with less light and have less CO2 and nutient demand.

    This way it is much easier for plants to transport the nutrients from the sediment to the tips of the apical meristems. If you increase light even more, the rates of transport are not fast enough to keep up, then you need to start adding nutrients to the water column. This way the plant does not have to transport them to the tips, the nutrients are already there.

    Likewise, at low light, the transport is not issue if the nutrients are only in the water column.

    So for both cases and for the case where nutrients are in both locations at once, less light is better.

    The same is true for CO2 non limitations as well.
    If you read and look up much about ADA, they use bubbles per second, rarely ppm's for CO2 and they also use their eye balls to see if they have enough CO2, along with lower light.

    Some seem more interested in ppms/nutrients etc and not enough about their plants, plants, not ppm's are what we are really focused on here.

    Plants are the real test.

    Tom Barr
  5. naman

    naman Prolific Poster

    Nov 12, 2005
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    It is a third time I say the same, and every time you say I am suggesting to limit algae with very low P dosage. Not at all.

    If Readers will read my Original text, they can see that almost on EVERY point you say I am wrong I said the OPPOSITE things, so in original text there was nothing wrong…

    Have you ever read the text?
    Did you read it as a whole or just separate phrases?

    This happens every time.
    Three times for now.

    Rather weird things is going on here…


    Tom Barr: "Naman, you are hung up on the issue that algae are P limited in our tanks, …"

    I said this:
    “What will be if algae appeared because of low CO2?
    Again we do massive water changes, and do less water column dosing.
    Plants become limited. Algae are not.
    Does it make sense to have less P in water column to have less algae biomass in this period? Yes.

    And I am not saying to use 1:15 to limit algae. NO.
    Just to make plants less influenced by occasionally lowered CO2 levels and to do not limit plants ability to assimilate lower CO2 concentrations. This can give more stability.

    When you dose less N (1:10-15 instead of 1:5), in case of low CO2 supply plants quickly run out of N and Rubisco simply do not have enough N to adapt for low CO2 concentrations.
    You WILL have a DOUBLE strike on System.

    I do not claim we have to limit plants on P or N.
    Nothing even close to this.
    Never said it. NO.
    As for C:p ratio I didn’t mean to limit plants growth with low P, or use low P to advocate low P dosing to have less CO2 demand. NO.
    I said there is simply NO NEED for such high P levels in EI (1:5) as we usually have no more than 30ppm of CO2 ! (as C:p = 106:1)
    That’s for sure :)
    Nore to use P limitation instead of using Light to limit plants growth.”

    The less P – the less algae biomass during disbalance, not when everything is ok.
    Or this is wrong?
    When would be more (in grams per day) and faster growth of algae during disbalance – when there is 3ppm LEFT in water, or when 0.05ppm?
    Where did you see I suggesting to use very low P dosage to limit algae? I never did.

    As for CO2, I said that when you under dosed Macro or during massive water changes combating algae attack it is good to have some N LEFT when P is almost zero as N needed for Rubisco to assimilate CO2 better, at the same time plants keep much more P buffer so will not slow growth so much as if we have lack of N added to this.
    This is a limited situation for plants, so some more N left would be beneficial for plants.
    It is known that limiting N has much more detrimental effect on plants than P, so in case of troubles it is better to have some more N left than P. To help plants with lowered CO2 levels, NOT to limit algae.

    Tom Barr: "Then you want to move into a PO4 limited system for plants (1st), then say that the algae are PO4 limited."

    Where I said this!?

    I said:
    “I am not suggesting limiting nutrients levels, N, P, or P along to get rid of algae or to manage CO2 demand. All I already said claims: when you suddenly have limited levels of nutrients or CO2 (very bad and quite often), [P] MUST BE THE *F I R S T* LIMITED NUTRIENT – NOT [N] “in case of problems”, not when everything is perfect.”
    “ANY system MUST have non limited nutrient levels for plants. Period.
    We must have non limiting levels of nutrients in BOTH systems, whether we prefer water column dosing OR rich substrate and lean water column.”

    I said with lowered for some time CO2 levels because of low bubble rates, dirty reactor etc you will have an advantage when plants run out of P first, before N, because they will assimilate more CO2 at lower concentrations and easer overcome this period.
    P buffer is much more in plants than N, so they will not stop growing totally immediately.
    This gives lag of time to fix the CO2 issue without algae attack.

    Or Seachem, Tropica and the rest of the World is wrong using 1:10-15 ratio in PO4:NO3 ferts?

    When I said “The less P – the less algae biomass during disbalance.”
    I mean less P left for algae during massive water changes (produce less biomass of algae per day) when algae attack is ALREADY taking place, not to dose very small amounts of P as a measure to limit algae! Can you see the difference in what I said ACTUALLY, and what you claim I said?

    Tom Barr: "Also, you make a very bad assumption here, PO4 is not locked up in the sediment."

    Where I said this!?
    I said PO4 is badly binded by substrates with high CEC as PO4 has negative charge. This is what I said. Anybody can check it out in my text. PO4 is slowly released from organics in sediments as substrate have limited O2 supply. Low labile organics (almost biologically degraded) as earthworm castings helps too. So we have a long term, slowly released supply of PO4 in substrate. What is wrong here?

    Tom Barr: "No, it applies when you reach that critical P or N level, the ratio does not matter until then."

    EXACTLY. This is a third time I am saying this.
    I am talking on benefits of higher P:N ration ONLY WHEN we already have problems with algae, so this is beneficial for our system when it is IN TROBLE.
    As higher ratio will not harm in any way when everything is OK (this is your words too), so we can use it safely.
    I do not suggested to use P limitation to limit algae or slow down plants growth with P instead of light. I never did.
    I mean in such situation mentioned above plants in better state when they run out of P FIRST, before N.
    Regular dosing must be non limiting. I said this many times.

    Or Tropica, Seachem and others should recall from sales their products with PO4:NO3 ratio 1:16 and 1:19 ?

    As for understanding the role of rich substrate, limiting plants growth with lights in ADA’s system and why it is good for user I already told not once I know this long time ago, - permalink. I have articles on every aspect since 2004.

    Not to mention what you said on Rock phosphate as unavailable for plants and claiming I am suggesting it as main source of P. I never did.
    I said Rock phosphate can be a good supplemental source of P for plants in rich substrates as it is not water soluble while being available for plants roots “at demand”. I posted links to read the background of this. BTW, rock phosphate is widely used as P source even when sprayed on leaves of terrestrial plants when micronized. Sure this is absurd to use micronized product in water column, but rock one could be a good thing.
    Instead of reading this info you say I suggesting rock phosphate as a main source of P in a planted tank instead of KH2PO4. I never did.

    Info on SFWMD and clue that % of elements in tissues and optimal concentrations in water is a different things is interesting, thanks for that.

    As for ADA’s system is EI + rich substrate… nothing common

    Tom Barr: "I learned about people before I learned about plants........."

    Me too.
  6. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    Okay, here is what you said:

    I read this.
    Limiting P is less detrimental than say NO3 or K.

    But this still has no relevance to a ratio.
    Unless you allow pure neglect and do not dose for several weeks, do not feed fish etc, have med to high light, CO2 enrichment etc.

    Ratios still do not come into play until something is limiting, and you have to go pretty far to do this.

    I'm sorry, I just do not think this is useful good advice for growing plants.
    ADA is not limiting the plants via PO4, it's in the sediment.

    Plants are well adapted to PO4 limitation, so they will respond more favorably to that than say Nitrogen limitation.

    But all this assumes neglect.
    I can make up all sort of weird notions about how to dose if you assume neglect and lack of maintenance.
    Go non CO2 if that is goal.
    Then it's much less of an issue and the intensity of the limitation is less serious.

    And that is what I've been saying for the last few times.

    I hypothesize it's wiser to use non CO2 and less light rather using N vs P pools. This way the intensity of the limitation is less and most fish waste has more N relative to P anyway..................

    And at lower rates of growth, fish waste alone can supply the desired pools of N and P, and at the ratio you are discussing here.

    The research data you mention is most likely based on non enriched CO2 planted systems, just like the advice I am giving.

    In a CO2 enriched system, the rates of growth and intensity of limitations are very different.

    Assuming that the CO2 is actually stable, that's questionable.
    Since stability and CO2 are an issue and goal, using non CO2 methods will only enhance this idea. Then the plant is well adapted to about +/- 2-3ppm of CO2.

    I've been to locations where the CO2 is stable, 3 ppm, 10ppm , 25 ppm in Florida, they have many springs that have plants in the downstream runs.

    Maintaining good stable CO2 levels is rather tough in aquariums, and less light helps this goal. At higher light intensity, it becomes progressively more difficult to do, especially at lower CO2 levels.

    What happens if you have 3ppm of CO2 and high light to the CO2 stability or say a non CO2 planted tank?

    What happens over a day cycle to the CO2?
    It is stable?

    If you have higher current, good mixing and response time to the CO2 enrichment method(well matched to the plant biomass/light intensity), then it should be fairly stable.

    This is independent of concentration.
    But with more CO2, you have more buffer in case you do not have good mixing, possible limiting factors that reduce the CO2 enrichment response time(so called lag time responses).

    In the springs, they have Millions of gallons per second flowing out from them, the nutrients and CO2 are stable due to the massive volume relative to plant biomass.

    Ina small pond however, the CO2 will vary from 0-10ppm every day, and the pH can go from 6 to 10.

    Hardly stable.

    But aquatic plants grow in both places.

    If and only if the PO4 is the limiting nutrient and the algae have no other source of PO4, which they obviously waste, sediment(ADA aqua soil etc), plant's leaching............

    So algae are not limited in either case.
    You seem to think they are.
    You need to consider the entire PO4 cycle here, not just what you measure in the water column of the water column pool.

    There are other sources of PO4 quite available to algae that you are not accounting for. If you are, where?

    Simply because you cannot measure the PO4 in the water column does not mean that PO4 is limiting. PO4 cycling is rapid and much more rapid when limiting. Basically it's degraded and taken up as fast as it's leached out.
    Also, the resolution of your test kits are very poor.

    If there is less N relative to P, the plants can still grow well if you have lower light, or also have non CO2. Fish waste, sediments, internal cycling of N can still supply enough to meet plant demands.

    You can play the game and try to provide a lower P pool vs N. But fish and sediments really throw all the ideas off.

    Aquariums are not ideal lab systems.

    They have fish, they have plants, they have bacteria(also a pool of PO4, N, and carbon), we export/prune, we add fish food, we add fertilizers, we have sediments rich in PO4, fish foods can vary and have hardly any P and have high N etc.

    When you get down to lower levels of PO4, these things really start playing a much more significant role.

    Tom Barr
  7. Tom Barr

    Tom Barr Founder
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    Jan 23, 2005
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    Yes, I agree with this.
    However ask the other question, why not have plenty of and N and P?

    I mean now you are talking about the plants here, so providing both, not just one, is wiser.

    I agree with what you are saying, but why not add PO4 as well?
    You said it's not to limit algae, so then why not add it?

    Just to slow down CO2 demand?
    Makes more sense to reduce light, go non CO2 etc if that is your goal.

    I think part of the confusion on my part is trying to keep clear the various things you are suggesting.

    => You say that under a bad algae issue/condition, not to dose PO4 as much, because it causes more CO2 uptake/demand in plants, not because it limits algae.

    I think that this is what you are saying.

    Still, the less light approach resolves this more effectively.
    It reduces every demand, not just PO4 or CO2 and it requires no test kit.
    Still, why you have algae in the first place and learning how to resolve that is the critical question, not secondary nutrient fixes that do not address the root cause.

    I'm not clear on why you pursue a method that does not address the root cause and mechanism. So yes, I am confused to some degree here with the logic behind this.

    Paul Sears never once told folks not to add any PO4 or to let it drop to zero, only to keep it low, around 0.1-0.2ppm. Most folks assumed that less was better.

    We see this in marine reef folks as well, but at lower levels, not absent, we see better results with PO4.

    However, at high levels of PO4 in FW systems, we see less algae such as the harder green crustose forms of algae, GSA(there are 3 species that are common).

    That alone is reason enough to have higher PO4 for many folks.
    Correcting the root cause of the CO2 issue, reducing light etc, general helps more effectively that limiting PO4.

    Folks did this for many years(limit/low PO4).
    It works okay too, but they used much less light back then.
    So 15ppm of CO2 was fine vs 30ppm.

    Still, in either case, 30ppm is still fine for plants and fish, same for .3ppm vs 3 ppm of PO4.

    Neither causes algae or is bad.

    By using less light, you have a much wider usable range for CO2, PO4, NO3 and most every nutrient.

    We know some of the upper non limiting ranges now by using very high light.
    Now, applying these ranges with some reason, we can provide a large nice target to dose and add CO2 using less light.

    Then we get much better stability and can address things like testing and user error, dosing mistakes etc.

    If you seek stability, using less light is one of the best methods there is.
    and light is also one of the few things that algae and plants actually might compete for if you had to pick.

    Tom Barr
  8. naman

    naman Prolific Poster

    Nov 12, 2005
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    4:01 AM
    Not at all.

    Keeping as less as possible PO4 in water column (a lot of nutrients in sediments instead of this to NEVER limit plants!) in case of imbalance (when it already happened, regardless of the reason) makes algae bloom much slower and much less severe.
    Pretty clear concept.
    You have more time to fix things, need less effort, no CO2 concentration swings due to very big water changes which enhances growth of algae - not plants during this period.
    This is the same as reach substrate makes possible to do not dose in water column regularly.
    You can miss week or more without any detrimental effect.

    Now imagine algae bloom already began in your tank.
    Think of two cases - PO4 0.1ppm before algae bloom, and PO4=1.0ppm.
    When it is 0.1ppm you will have much less algae per day, isn't !?

    At the same time even when plants run out of PO4 they simply slow down growth, and this slow down is orders less than when they run out of N ! (remember Ole’s test?) They virtually almost stop growing and algae have more chances.
    So it is way better to always have more N pool for plants shifting ratio to 1:10-25.

    More over, with PO4:NO3 ratio 1:10-15 when substrate becomes pure or you do not dose enough ferts in water column (regardless of the reasons - lazy, no time, lack of knowlege...) plants always have enough N (you always have excess of N in a system as for P) to manage with temporary lack/fluctuations of CO2 concentration as they have large pool of N in tissues and can maintain normal growth for a while being satisfied with less CO2.
    So you do not have pH-controller, or sitting in front of aquarium all days watching for green color of dropchecker.
    And you can use east method in much more cases than with “water column only dosing method”, especially using PO4:NO3=1:5...

    Even more. When there are always more N than P (say PO4:NO3=1:10-15) plants "get trained" to live with less CO2 using more N and building their insurance in form of Rubisco which helps fix lower CO2 concentrations.

    Sure we can limit plants need for CO2, N and P reducing light intensity, but in case of imbalance rests of PO4=1.0ppm in water column gives more severe algae bloom than with PO4=0.1ppm.

    This is not call for negligence or to try to limit algae limiting PO4 levels, NO.
    This is Insurance = Stability.

    Simple as that.

    This is why ADA's approach (reach substrate + low nutrients level in water column + noon burst lighting to limit plants growth) is more stable, more forgiving for aquarist's mistakes.
    Low PO4 levels in water do not limit plants, but greatly improves Stability of your tank and much more user friendly.

    When you have excellent growth and no algae at PO4=0.05ppm in water column why the heck we need to constantly keep 0.5-1.0 ? To have x5 algae in case of imbalance (dead fish for example) and make more water changes fighting it?

    ADA's Light management + nutrients location + noon burst = completely different system of keeping planted tank than EI or even EI+AS.
    ADA's approach greatly out competes all "water column dosing only" methods and others...

    I remember several years ago you claimed no one needs reach substrate to have healthy tank.
    The same as we can do it with sponge filter instead of a canister pumping 6 volumes per hour. That is partially(!) true. But you missed of such simple things as Stability and Usability of a method as hole.
    This is why many EI funs really (ask them yourself) do not use 1:5, but 1:10-15 shifting to PPS-pro, have pH-controllers and dosers etc. This is because they are tired of constant severe control over their CO2 levels and dosing.
    They are tired of that how fast algae grow when they did something wrong as they have tones(!) of PO4 left in water column as they dose 1:5 instead of using 1:15 and to put ferts in substrate… etc etc etc
    And this is why you constantly repeating “watch for CO2!”. This is just wright, but there is a method which allows to watch for it much less, the same as for ferts dosing.
    The trick is similar to light – when plants have lots of ferts they really need much less light than many folks might think, but this is thanks to the large pool of N (esp with reah substrate), not P ! Think about…

    And less PO4 left in water at the very start of imbalance means much less algae growth in case of problems and less maintanance to fix it.

    And as I can see for the last two-three years, day by day you admitting and using in practice elements of ADA’s approach. There is no cense to argue about that, you do it :) And you have no choice.
    Sooner or later you WILL totally switch to their System, as most of others.
    Interesting is that folks who switched to ADA’s system stopped discussing science of a planted tank – they simply use system, that’s it.
    So my approach was to “re-engineer” ADA’s system to use it Consciously.

  9. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Jan 23, 2005
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    4:01 AM
    Well, this assumes you are messing something up to begin with and error on making mistakes..........

    If that is the case, it's 100X wiser to use less light intensity, not less PO4.
    Something I've advocated for nearly 2 decades.

    Then the nutrients do not matter as much if at all.
    Then you also do not need to worry about testing or keeping close tabs, thus you have a great deal more wiggle room and resiliency with any dosing routine, not just low PO4.

    This is basic plant growth physiology, it all starts with light, which for us, is highly stable , unlike the nutrients.

    See light above, this makes what you are arguing far stronger in the favor or reduced light, not reducing limiting nutrients......... to control growth rates.

    If we provide non limiting nutrients, non limiting CO2 for lower light levels, then there's no issues.

    It's when folks want to have their cake and eat it too, they want high light and low rates of growth, which is very wasteful for electric, favors algae and sets you up for failure etc. At lower light, there's no issue here, I've done this hobby for many years to know better, so have many others.

    This is also supported strongly by every research paper out there, with more light under non limiting conditions, you get more algae/plant growth, this is very strongly positively correlated.

    I'm not sure why you are trying to argue in favor of limiting PO4 under high light, if the goal is to limit algae and control plant growth, it's painfully obvious that light is the best method to do so.

    If it's under low light, well then, it does not matter because lower light systems are very easy and highly resilient, high or low PO4, because the rates of growth are slowed down as well for both plants and certainly for algae.

    Thus use have less CO2 demand and less PO4 demand.
    Adding more CO2 or PO4 does not hurt, nor provides any ,margin or error...because.................the tank is light, not PO4 limited.

    I've stated this and mentioned this concept in the past, many times on many forums.

    Sure you can use PO4 limitation as "choice", but given the goal and ability to maintain a nice aquarium over time, using PO4 limitation is a poor choice given the other trade offs vs simply using less light.

    I can miss all dosing at all if I use less light:cool:
    Using less light makes things far easier no matter what.
    CO2, PO4, NO3 etc etc.

    Why might the algae be present to start with?
    Poor care. Aquarist cannot keep up with things etc.
    They neglect the tank.

    The question is how did you get algae in the first place?
    Killing and controlling algae is not an issue really.

    Reducing nutrients does not slow the growth, often times, as many have long observed, it slows plant growth which in turns allows the algae to grow effectively.

    Algae, and plenty of research has shown this with macrophytes, grows better at lower levels of PO4 than any plant.

    The Everglades is a well studied system with plants and algae.

    They do not know quite where PO4 will limit algae growth there, it's below 0.010, about 10parts per billion.

    I can promise you, nor any aquarists can measure this low with an accuracy 3ppm.

    They are limited at about 20-50parts per billion.
    This is PO4 limited system.
    They cannot control light here, we however, can and do.

    I'll go over some of the same things I have in the past if you really want, but I think you have missed a large part of how plants grow and what drives growth here.

    You need to look at the big picture and what the goal really is before hand.
    If you seek more resiliency, then use less light, good sediment ferts and water column ferts.

    If they are non limiting, then the plants will grow and define the system, this is true in natural systems as well as aquariums.

    If you assume "messing the tank up" and "adding algae", more specifically inducing a particular species of interest, you need to be specific on how that was done and which species of algae was used to do this.

    It is no longer just a plant issue if you add algae, you need to know about the algae, why it's growing now, what species etc much more.

    Step back and think about this. The situation and logic you are setting up here is following through nor answering the questions you are asking.

    Tom Barr

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