Discussion in 'Algae' started by jarthel, 23 Nov 2009.
http://www.thekrib.com/Plants/Fertilize ... onlin.html
The limiting phosphate idea fell out of favour a while ago see what Tom Barr has to say on the subject in this thread:-
It's back to the nutrient reduction question, as long as you are prepared to have a "low nutrient - low productivity" aquarium, control of phosphate levels in the water column will reduce the amount of the Green Algae, the "Chlorophyta".
What you have to remember is that they are are ancestral to all the other "Green plants", and their photosynthetic pathways are exactly the same as the higher plants (Mosses & liverworts, "Bryophytes", Ferns "Pteridophytes" and the flowering plants "Angiosperms"), and they will utilise the same wavelengths of light and macro/micro nutrients, so any attempt to starve the algae of nutrients in the water column, (or light) is doomed to failure.
There are also practical problems to phosphate reduction, tap water in the UK is fairly high in it from agriculture, treated sewage, optical brighteners in detergents etc, and this is exacerbated by the addition of "plumbosolvency" by the water companies, a phosphate compound designed to bind with the lead from lead pipes, and precipitate it out from drinking water.
But phosphorus doesn't have a gaseous phase, so either rain-water or R.O will be phosphate free, and if you use a substrate with a high CEC (orthophoshate is an anion, but CEC will give a close approximation), a clay for example (either calcined or not), any phosphorus (either inorganic or organically bound from leaf mould etc.) added to the substrate will tend to stay there and be available to rooted aquatic plants, but not algae.
This "phosphate stripping" approach is very widely used for rivers etc. in Europe and the UK, and has generated a large amount of scientific literature (for those who are interested "the Everglades" periphyton pdf, Tom linked in is well worth a read).
Exactly, that's why PMDD was unsuccessful and had to be modified to PMDD+PO4, which is hugely successful. The data is over a decade old, and at least one of the authors later admitted that the conclusions were wrong. There is always a danger of mis-correlation when you test hypotheses in the manner:
If you do not have control, and if your measurement techniques are unsubstantiated in experiments, there will always be a question as to the validity of your conclusions, regardless of how compelling they may seem. And that's exactly what happened to Sears and Conlin. In the planted tank it has been demonstrated that there is no correlation between high PO4 levels and the appearance of cyanobacteria, and in fact cyanobacteria is now correlated to a deficiency in NO3.
I don't have cyanobacteria in my tanks and I've added PO4 levels above 10ppm so these conclusions can't be true. It could be theorized that the combination of PO4 plus something else may be responsible for a rise in cyanobacteria but empirical evidence has shown that PO4 alone is not responsible.
And I can only add what I've seen with my own eyes, excess PO4 does not cause algae .
I'm not trying to preach to the converted, but these are my own observations.
After advice sought round here, I raised my PO4 levels considerably whilst combatting some GSA (with success, I might add ) and I didn't see any other type of algae develop.
Well Chris I think it's important that the results of the principles we advocate can be corroborated independently by any individual. The results you see in your tank indicates that the results are repeatable, that they are not just the fantasy of a few extremist lunatics. Normal people, who follow the non-limiting principles see positive results so the evidence is unequivocal.
We know a bit more now and it 's easy to deduce where Sears & Conlin went wrong. It's entirely possible that they had not anticipated the correlation between poor nitrate/flow with BGA. If they were not paying attention to, or were not capable of monitoring and controlling the NO3 levels then this inattentiveness could easily have lead to a BGA inducement. So now of course, once BGA blooms from it's cyst form then it naturally will feed on any nutrients in the water column. So if you feed it more PO4 then absolutely it will have accelerated growth, leading to the false conclusion that PO4 and BGA are correlated.
This scenario is what plays out even today in countless tanks around the world. There are two issues. The first is causality. The second is exacerbation. In our tanks, the blooms of different algal species can be initiated by different nutritional deficiencies. Some algal species bloom when plants suffer malnutrition of NO3, others of PO4, others of CO2 and others bloom with deficiencies of the combinations of the three.
If you have a CO2 deficiency and if the tank is eutrophic, then the CO2 related algae will feed on the nutrients after it blooms. Naturally, the growth rate of a CO2 related algae must be higher in a eutrophic tank than in an oligotrophic tank. This is undeniable, but this is an exacerbation, not a cause. Ultimately, the long term solution is not simply to limit the nutrients, because that only hurts the plants in the long term. The real solution is to fix the CO2 so that the plants don't suffer algae related to CO2 deficiency.
This is Didiplis diandra suffering from poor CO2. A type of thread algae attacks. In the eutrophic tank this string can grow 6 inches in a day. Thinning out the bed to encourage better flow as well as a minor injection rate increase eliminated this algae within a matter of days. No adjustment to the nutrient levels were ever contemplated.
Here's another illustration I use a lot. This is Pogostemon helferi in a eutrophic tank. Nutrients were limited for 5 days and then immediately resumed. As can be seen, some of the leaves are suffering extreme case of GSA. Other leaves are immaculate. See if you can determine which leaves grew under the 5 day PO4 limiting condition and which grew under the resumption of eutrophic dosing.
Scientists around the world, for generations, have linked nutrients to causality, to the point where it seems intuitive, yet, every day a growing number of hobbyists see just the opposite demonstrated in their tanks. In fact, we can break just about every one of their rules and instead of seeing increased algae, we see increased plant growth. Perhaps, someday, instead of insisting that the nutrient limiting is the way forward in our tanks, based on what they perceive is occurring in the worlds environmental systems, they may take a closer look at our tanks and decide that instead, perhaps they have an incomplete picture of the events occurring the worlds ecosystems.
Science progresses by experimentation, you can have as many scientists as you like reporting findings that agree with the orthodox view, but it only needs one repeatable heterdox finding for the theory to either be amended, or become invalid and be discarded all together. The laws of the physical environment have withstood the tests of time, but many biological theories ("Evolution by natural selection" for example) are more difficult to prove.
As Clive says he is "mainly preaching to the converted" but If he feels his findings are of such significance that they will re-write one the fundamental principles under-pinning the science of Ecology, he needs to find an Academic Institution where his theories can be rigorously tested, under experimental conditions, and the results published in a peer reviewed journal.
I can't tell you whether he is right or not, and look forward to seeing the results, but if he is right, his work will invalidate the huge volume of scientific research over 150 years by many scientists choosing to work in a field which is very unlikely to win them much in the way of personal advancement, money or awards. As he has invoked the scientific process, I think it is probably time for him to "put up, or shut up".
Sounds like a fair proposition.
I don't see a contradiction between what ceg4048 is saying and the observations from the abstract quoted by dw1305 above. If you remove phosphates from an aquatic system the overall productivity will go down be it plant growth or algae growth.
If there is insufficient or no aquatic plants then in the presence of high light and high nutrients concentrations you will get algae. If there is high concentrations of nutrients but one such as NO3 or CO2 is highly limited then this will favour algae growth such as cladophora as they can take advantage of this nutrient deficiency.
Walstads Ecology of the planted tank book presents many papers from peered reviewed journals showing that increased levels of nutrients does not correlate with algae growth.
Well, I'm not looking for personal advancement, money or awards either, that's for sure. Not only that, but I'm not trying to prove what is. It's almost impossible to prove a theory. So I can't prove my theory correct, but the results do indicate that there is something wrong with the theory that nutrients cause algae.
What we, the converted do have is strong correlation showing that high levels of PO4 is not a causal factor. So I may not be able to prove the causal factors, but I can certainly prove what it is not. I've already put up the evidence. I've shown you the results of my efforts. You have yet to explain why I don't have algae with such high levels of PO4, so I don't think it's I that should do the shutting up. In any case, as Brenmuk states there's plenty of peer reviewed data out there. On another thread Barr pointed out Why is periphyton so abundant in the Everglades? which is a study of the seasonal eutrophication of a section of the Everglades. Page 29 of the file shows a fairly good image of the end results of eutrophication in that particular environment. You can see that after a transient period of increased algae (page 28), a 6 fold increase in the PO4 levels has virtually eliminated the algae and is replaced by plants. Is this an illusion?
Huge volumes of scientific research for over 150 years does not match what I see in my tank, therefore I can't speak to it's validity. What we can say is that in our tanks, nutrient limitation is definitely not correlated to increased plant health, and that in the planted tank, if optimizing growth rate is the goal, then following the policy of unlimited nutrients is more successful than following the policy of limiting nutrients.
In both tanks at the time when pictures have been taken level of NO3 has been around 80ppm and PO4 above 10pmm (out of scale). These levels have been kept for about 4-6 weeks before pictures have been taken.
Bigger tank (on the top) is HT tank with CO2 addition. Small one is LT with liquid carbon suplementation (no CO2 injection).
Edit: Below picture of bigger tank, with PO4 and NO3 limitation. PO4 has been removed by Rowapos in the filter. NO3 around 5ppm, so in fact only PO4 has been limited, but only for plants, as you can see.
The Everglades periphyton paper says that the end stage of the eutrophication process is a stand dominated by Typha, and that would be the end result in the UK as well, the victor is a large "chunky" plant, capable of rapid vegetative spread, with widely dispersed seeds and a linear growth response to nitrogen. As the paper explains the interaction between the periphyton, the higher plants and the environmental factors is a complex one. This also another case where the highly calcareous nature of the water and marl is a factor which limits the availability of many nutrients, and particularly phosphorus.
My point would be if you could return to the levels of macro-nutrients before eutrophication we would have a complex wetland with a high diversity of plants (including insectivorous ones like Utricularia, diatoms, filamentous green alga, cyanobacteria etc.) , and as eutrophication continues the diversity of all these plants will have declined as the ones with potentially quicker growth rates in eutrophic conditions, replacing those adapted to more nutrient poor "oligotrophic" conditions, and this replacement will occur in the algal community as well as amongst the macrophytes.
In the Glades, the natural species is the Caldium grass, the added PO4 is changing things to a more Typha dominated system. Cattail can out compete Cladium easily when things are PO4 rich. when it's lean on PO4, then the Cladium does better. More Cattail is bad news for this natural system. Aquariums are not natural at all however.
As far as a more submersed plant specific citation, I think Bachmann's paper does the correlation example much better to our specific cases/observations:
http://fishweb.ifas.ufl.edu/Faculty%20P ... ophyte.pdf
See figures 3 for N and P.
As far as algae go, the cattail will shade out the periphyton also much more than the Cladium, so we have light issues going on, these dramatically affect results. We often use algae species as indices of pollution for environmental monitoring. Diatoms are particularly good for this for freshwater. We can shift things around as far as algae with light, N, P, CO2 and herbivores likewise for our much more controllable aquarium systems.
Some species suggest we are close, some suggest we are way off base.
Likewise, plants themselves are even better indicators of health than algae.
They are the focused goal we desire, so they are the best solution for a choice of a "standard".
Pick a really wimpy hard to grow plant.
Or several species.
If they do well, flourish, and no algae, then that is a good reference.
Most periphyton algae peak at about 200 micromoles and then decline very slowly with increasing light/PAR.
the slope really drops off as far as growth rates when you go down from 200 micromoles.
A good paper if you look at the PASr and growth rates of the periphyton.
Now add this with a observed PAr value of say 50 micromols for excellent plant growth even in deep tanks, and you can see low light limiting algae growth rates, good ample CO2/nutrients for plants.
But with more light, the plants also grow faster as well :idea:
So what might be going on there since we can see aquariums with higher light also algae free etc?
Well, the time it takes for the algae to colonize these faster growing moving targets(plant leaves) plays a significant role, so does our pruning and the shading if you neglect to prune and the weeds cover the top layers continuously with new non infested new growth?
It's not a static thing.
However, we know also that higher light makes life hard for management of CO2, nutrients, plants etc and you can muck things up much easier, in other words, more light= less wiggle room as far as management is concerned.
With such perspectives, I think folks can come to a reasonable conclusion without feeling too uneasy about it.
I also think the basic questions and hypothesis laid out by Paul and Kevin where well founded and a good approach was done, however, they needed to test several of their hypothesis against a known reference, which they did not have enough control to do at the time.
I did so that answered those questions and we moved on from there.
We still lack the specific knowledge what causes "algae" etc for many species, we know what causes good plant growth for the most part however.
I'd stick with that and if you really like algae and want to study that, then focus there.
You are not going to uncover much about algae using casual observations with aquariums.
Some seem to think they can or with their NO3 test kit etc.
If it where that simple and those methods worked, we'd figured everything out decades ago
We also have to be very careful about which system and which location we are talking about when applying the research to.
This gets a lot of folks into trouble.
Northern lake studies are not the same as Florida lakes for example.
But even in Denmark, we see similar observations if we look.
Likewise, we see similar issues with algae where plants are or are not in FL.
There's not much correlation as far as nutrients, in our aquariums or the natural systems.
In some systems, adding PO4 causes algae blooms, others? Cattails and aquatic weeds!
Algae is much easier to kill, let me tell you.
So the pollution factor weighs heavy with me and the management of natural systems/agriculture/public water ways/marine systems etc
Algae and aquatic plants can be huge issues that affects us, nature, native species etc in dramatic ways.
In horticulture, many folks want to grow "weeds" for aesthetic purposes however.
So these weeds are now nice plants
Thanks Tom, you're right that these are not at all simple systems, and trying to extrapolate from one to another or from one to a tank may not bear fruit. The author in that trophic state indicator article even warned of that in his discussion. In any case, the lack of correlation between nutrients and algal blooms is a powerful insight, and it's exactly what we see - except for the observation that the lakes with the highest nutrient content were algae dominated, with SAMs "predictably" absent. He even mentioned that it was predictable. That was more than a bit of a surprise. Does that imply some kind of nutrient threshold in Florida lake systems?
As far as tank dosing techniques, I suppose it goes back to what you've taught regarding goals and objectives. If the objective is in approximating a periphyton dominated environment, and if one focuses on biodiversity in terms of the population and variability of organisms in the biofilm, then that will drive a different strategy than one in which biodiversity is interpreted as the ability to maintain a high population of, and multiple species of weeds. The converted agree that this is horticulture with an aesthetic purpose.
Nope, but it's a good thing to think about.
Well, overloading any system will kill off most natural states of diversity. So things like wastewater.spetic systems, hillbillies dumping their bed pans out in the back yard........
It's the rate of dosing that's the issue, not the ppm etc itself.
Well, for the Glades, how do you reduce the PO4 down to 3-10ppb, Billion that issue.
Wetland treatment zones is the only practical method, but the farmers do not wanna give up the land.
They wanna grow sugar cane and trash their soil.
I suggested to do a land swap every 50 years.
Not popular either, but they get darn rich sediment without adding PO4.
You think the plant issue is tough, try people and getting them to agree to a darn thing.
CA has even worse issues.
Thanks again, some more interesting references. Same in the UK, we managed to drain most of Fens by the end of the 19th Century, and some formerly Cladium mariscus ("Saw-sedge" in the UK, it's from the Sedge family - Cyperaceae) dominated habitats, "King's Sedge-moor" are now mainly agricultural with duckweed covered eutrophic drainage ditches and no Cladium (or Chara spp, Utricularia spp. etc) at all. Cladium does hang on in a few places (which are managed for it) Wickham Fen National Nature Reserve (NNR) and Cors Goch NNR, for example. It's more common in Ireland, where more base rich Fens are still intact (East Burren wetlands for example).
Difficult to get an accurate estimate, but probably for the lowland agricultural UK the environment has about x5 the amount of fixed nitrogen it would have naturally. Phosphorus is a more difficult estimation, but again for many soils and lowland water courses the phosphorus reservoir of (clay bound and as calcium phosphate compounds) phosphorus is immense, and would/will take centuries to deplete.
However I still think we are to some extent talking at cross purposes, my basic premise is that nutrient limitation in the water column(including CO2), which Tom alludes to in his post, is a viable alternative for planted tanks. It certainly doesn't give you optimum plant growth, but it is a simple approach, and gives you long term stability. I'd also suggest that for many people who are struggling with continual algal blooms, unbalanced nutrients etc that they would be better returning to the low tech approach, finding a low nutrient/low growth datum, and then, if they wish to have faster plant growth, and grow a variety of more demanding plants, over time raise nutrients and CO2. I think of this in terms of "potential", both the potential for growth, and also the potential for things to become unbalanced, low potential slow growth and slow change, greater potential greater growth but greater potential for things to go "wrong."
I only started posting on this forum, after a long term lurking and reading what have been a stream of brilliant posts, because I had become increasingly concerned that it had stopped being a forum where different experiences and options could be discussed, and had become a forum where you had to agree that "high nutrients, High CO2" was the answer to every question, and if you tried to post any other view your opinions were ridiculed, presumably with the intent of intimidating heterodox posters into not posting. I'm fortunate in that I'm in a position where I have the solid bed-rock of a scientific background (in a related field) and access to all the relevant scientific literature. I don't know whether I'm right or wrong, but I would suspect that the high priest of "high nutrients, High CO2" know, without a scintilla of doubt, that they are right.
I'd suggest to all members if the forum that this forum needs to remain a "broad church", and that they should keep observing what happens and keep a dose of healthy scepticism, particularly for all more "fundamentalist" posters.
Couldn't agree more. I've got so fed up listening to the EI brigade that I no longer bother posting.
For me its not about high nutrients - I run (or attempt to) an NPT ie a low nutrient low maintenance tank. I don't want algae and find the best way to avoid it is to provide my plants with all the nutrients/CO2 they need (for me this comes from food + soil). The point is unless you balance the light with nutrients/CO2 and plant demand then you end up with deficiencies which usually ends up with a single dominant plant doing all the growing and/or an algae take over (thats my experience so far).
All this talk about everglades and natural lake systems misses the point because what most people are trying to achieve (me included) is totally artificial with plants and fish from all over the world in a small volume of water with no algae.
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