Algae are nutrient scavengers

First of all algae don't scavenge. If there is any scavenging to be done it's done by the plants. Plants are the ones that need the most nutrition so their work is a lot harder. Algae don't care about nutrient levels. They can succeed whether there are high levels or low levels of nutrients in the water column. So the idea that algae are hanging around waiting for plants to finish feasting just so that they can fight over the last remaining crumbs of nutrients is absurd. I mean, what's the implication? That the nutrient level must be exactly zero by the time lights are off in order for the algae to starve to death? How does one propose to accomplish that? Good luck.

Non-growing surfaces are easy targets for algae. Plants that are growing are able to resist attachment. Inorganic surfaces will always have some algae on them because they don't grow. Light is the single most important factor in algal growth so a white inanimate object sitting under bright lights will typically attract algae. That's just how life is so we need to get over that fact. I have external diffusers and if I wrap them in cloth to block the light they don't get algae and I never have to clean them. If they are open to the light they get algae. This is completely independent of nutrient levels.

What's more important is keeping the plants - and tank in general healthy as a system, and that's accomplished by having well fed plants, good CO2 and good circulation - and to stop obsessing about whether we have excess nutrients or not. It's a pity people don't obsess over whether they have excess light. Then there might actually be some progress.

Cheers,

Hi all,
I'll "nail my colours to the mast" straight away, and say that I have an academic background in Botany and Horticulture, and I've worked as an Ecologist (mainly looking at nutrient cycling in terrestrial grasslands) for almost 20 years. From that background I'm happy to accept that nearly all plants (and in this I'll include all photosynthetic organisms) will show elevated growth with the addition of CO2 and macronutrients (as long as micronutrient levels and PAR are not limiting).
If anyone isn't sure of the effect of additional carbon, I recommend this experiment using Cabomba <http://www-saps.plantsci.cam.ac.uk/articles/cabomba/cabomba.htm>.

However I am to some extent wary of adding both CO2, and to some extent macro-nutrients, to the water column in aquaria. The reason for this is the differences between "sustainable" and "optimal" growth. As a general rule In natural communities the most biodiverse and stable communities are those that occur in nutrient limited conditions, this is partially because nutrient limited plants are physically smaller and you can get more individuals on the same area. I also know that patchy environments have a higher "edge effect", and support more biodiversity.

My suggestion for a planted tank that will never suffer from "outbreaks" of algae (or rapid unbalanced plant growth), is one with reasonable amounts of PAR, but extremely limited nutrients in the water column, and a lot of structure (wood, peat blocks, bark, stones etc.), with a "biofilm" present. This removes the balancing act between nutrients, CO2 and light. Nutrients are always severely limiting. Growth will never be optimal, but it will be sustainable.

You may not be able to grow all the plants that are available, but you can still grow a good range, and there is very little that can go wrong. In fact the only parameter that I measure regularly is conductivity, and I aim to keep this under 100 microS. Very occasionally I do add a small ball of clay with grains of "growmore" to the root zone of Echinodorus, and I initially added a small amount of both leaf-mould and calcined clay to the silica sand substrate in the area in which I planted the Cryptocorynes, but the tank in the photo has been running for over 4 years and still has acceptable plant growth.

<>

Therefore, with the following proviso's:
if you are happy to have some "biofilm",
some build up of mulm (and DOC)
grow plants which can grow in low CO2/low nutrient conditions,
make regular small water changes, (with good quality water low in nutrients)
don't over stock with fish
accept Asellus, MTS, Shrimps, Planaria etc in the tank.

You can have a tank with good plant cover and little algae that is very stable and resilient.

cheers Darrel

Hi,
Sorry, but I don't buy this theory and I don't really believe this to be true:

dw1305 said:

However I am to some extent wary of adding both CO2, and to some extent macro-nutrients, to the water column in aquaria. The reason for this is the differences between "sustainable" and "optimal" growth. As a general rule In natural communities the most biodiverse and stable communities are those that occur in nutrient limited conditions, this is partially because nutrient limited plants are physically smaller and you can get more individuals on the same area. I also know that patchy environments have a higher "edge effect", and support more biodiversity.

Click to expand...

I see no correlation between biodiversity and organism size. You can pick any terrestrial or aquatic system on the plant and by a large margin, the most productive systems are those that are high in nutrients. Of course, those nutrient levels may not be found in expected places such as in sediment. The Amazon Rain Forest is big, with both big and small creatures, and is the very definition of biodiversity, yet the sediment is very poor in nutrients. The nutrients are stored in the forest litter itself so the plants there have developed special adaptation and symbiotic relationships to pull nutrients out of the litter.

Highly productive aquatic systems such as those found in the Pacific reefs, such as Hawaii or The Marianas Islands normally have their nutrient stores thousands of feet below the summit which feeds the planktonic life forms, upon which is the basis of oceanic production. You cannot have high productivity without high nutrient loads, and the productivity of a system determines the level of it's biodiversity.

dw1305 said:

...However I am to some extent wary of adding both CO2, and to some extent macro-nutrients, to the water column in aquaria. The reason for this is the differences between "sustainable" and "optimal" growth.

Click to expand...

Yes, but what does this even mean? Fish tanks are not independent entities living on their own. Therefore "sustainability" is a relevant expression only as it relates to the extent to which the owner of the tank is willing to sustain it. "Optimal" is another expression that has no meaning within the context of a man made system. What parameter(s) are you using as a metric for optimal? Growth rate? If so then it's clear that more nutrients+CO2 generates higher growth rates and better plant health. Is the expression "optimal" being used to describe some sort of balance, or ratio, such as the ratio of maintenance required versus growth rate? If so then each person must decide how much maintenance they are willing to do, how much money they are willing to spend and how much growth performance they expect in order to determine what is optimal for them

dw1305 said:

My suggestion for a planted tank that will never suffer from "outbreaks" of algae (or rapid unbalanced plant growth), is one with reasonable amounts of PAR, but extremely limited nutrients in the water column, and a lot of structure (wood, peat blocks, bark, stones etc.), with a "biofilm" present. This removes the balancing act between nutrients, CO2 and light. Nutrients are always severely limiting. Growth will never be optimal, but it will be sustainable.

Click to expand...

OK, that's fine, but that's only one of many possible scenarios. Severely limiting nutrients, which only produces severely limited growth is not my idea of an interesting tank. I have huge PAR levels, huge CO2 levels and enormous nutrient levels and I don't have algal outbreaks. Of course this requires a lot of attention, but I'm willing to pay it. If I were not, then I would have to lower the PAR as well as nutrients+CO2. Far more often than not, people have high PAR and insufficient nutrients+CO2 and that does cause algal outbreaks. The OP claims that nutrient levels in the water column is the causal factor and what we are saying is that the causal factor is high PAR. Certainly, the algae will feed on the available nutrients so this can exacerbate the issue by accelerating the algal growth, but the presence of nutrients alone does not cause the algal outbreaks. This is the key point.

dw1305 said:

You may not be able to grow all the plants that are available, but you can still grow a good range, and there is very little that can go wrong. In fact the only parameter that I measure regularly is conductivity, and I aim to keep this under 100 microS. Very occasionally I do add a small ball of clay with grains of "growmore" to the root zone of Echinodorus, and I initially added a small amount of both leaf-mould and calcined clay to the silica sand substrate in the area in which I planted the Cryptocorynes, but the tank in the photo has been running for over 4 years and still has acceptable plant growth.

Click to expand...

Well, I mean, suppose I want to grow all the plants that are available? Then what? Am I simply outta luck? That's not a very scientific solution. A much more viable solution is to learn and understand the role of nutrients and CO2 as they relate to plant health. I don't ever worry about conductivity and it's often above 750 microS. That whole clay ball thing is completely unneccessary. My Echinodorus grow just fine with water column dosing which results in a hypereutrophic environment.

The thing is that if you are satisfied to have the plants in your tank merely eek out a living then that's fine, lower the light and do the "sustainability" thing. That is certainly a valid. But I want my tank to sing, and I want it to amaze me. And that is very difficult to achieve under limiting conditions. The plants below were dosed with over 60ppm NO3, 10ppm PO4 weekly, had high CO2 and were under 1/2 kilowatt of T5 with reflectors. I guarantee you that you cannot achieve this by starving the plants. And look Ma, no algae.










Cheers,

Hi all,
I thought that would probably be the response, and I'm not looking to pick an argument. It is very much "horses for courses", and I don't think we will ever agree. However just to answer some of Clive's comments, which I do think are to some degree valid.

I see no correlation between biodiversity and organism size. You can pick any terrestrial or aquatic system on the plant and by a large margin, the most productive systems are those that are high in nutrients. Of course, those nutrient levels may not be found in expected places such as in sediment. The Amazon Rain Forest is big, with both big and small creatures, and is the very definition of biodiversity, yet the sediment is very poor in nutrients. The nutrients are stored in the forest litter itself so the plants there have developed special adaptation and symbiotic relationships to pull nutrients out of the litter.

Click to expand...

Productivity is "biomass", I am talking about biodiversity, I agree with The Amazon comments, as you say the whole system is both nutrient poor and biodiversity rich, because the few nutrient present are continually being re-cycled, and the input of solar energy is huge.

Highly productive aquatic systems such as those found in the Pacific reefs, such as Hawaii or The Marianas Islands normally have their nutrient stores thousands of feet below the summit which feeds the planktonic life forms, upon which is the basis of oceanic production. You cannot have high productivity without high nutrient loads, and the productivity of a system determines the level of it's biodiversity.

Click to expand...

This is back to the rainforest, in this case even within a zone of upwelling this is relatively nutrient poor water, if you want to see nutrient rich sea water stand on the Seven Bridge above the Bristol Channel gyre in the spring, that is nutrient, (and sediment) rich water, and

"the productivity of a system determines the level of it's biodiversity"

Click to expand...

is, no two ways about it, wrong, if you felled an area of rainforest and planted a C4 grass - Sugar Cane for example, productivity will be greatly increased, although you now have a single plant "monoculture", and exactly the same amount of PAR. The highest theoretical productivity would be a simple plant mixture with a canopy that fully exploited the incident PAR.

OK, that's fine, but that's only one of many possible scenarios. Severely limiting nutrients, which only produces severely limited growth is not my idea of an interesting tank. I have huge PAR levels, huge CO2 levels and enormous nutrient levels and I don't have algal outbreaks. Of course this requires a lot of attention, but I'm willing to pay it.

Click to expand...

And you can see the result, no-one is going to argue that my tanks are anything like as beautiful, or diverse as yours, but they are much more stable, and I am willing to bet that for many of us less skilled aquatic gardeners my approach offers a more achievable, and sustainable objective.

Well, I mean, suppose I want to grow all the plants that are available? Then what? Am I simply outta luck? That's not a very scientific solution. A much more viable solution is to learn and understand the role of nutrients and CO2 as they relate to plant health. I don't ever worry about conductivity and it's often above 750 microS. That whole clay ball thing is completely unneccessary. My Echinodorus grow just fine with water column dosing which results in a hypereutrophic environment. The thing is that if you are satisfied to have the plants in your tank merely eek out a living then that's fine, lower the light and do the "sustainability" thing. That is certainly a valid. But I want my tank to sing, and I want it to amaze me. And that is very difficult to achieve under limiting conditions. The plants below were dosed with over 60ppm NO3, 10ppm PO4 weekly, had high CO2 and were under 1/2 kilowatt of T5 with reflectors. I guarantee you that you cannot achieve this by starving the plants. And look Ma, no algae.

Click to expand...

Yes, that is my point I am happy to have a limited range of plants in my tank merely eek out a living, but this is not because I don't fully understand the role of nutrients and CO2 as they relate to plant growth, it is because I want stability above all, not an all singing, all dancing tank.

cheers Darrel

dw1305 said:

...Yes, that is my point I am happy to have a limited range of plants in my tank merely eek out a living, but this is not because I don't fully understand the role of nutrients and CO2 as they relate to plant growth, it is because I want stability above all, not an all singing, all dancing tank.

Click to expand...

Hi Darrel,
Yes, and I think that's great. As I mentioned earlier, if that's your focus then that's just as valid a course of action as any. The issue here however, as stated by the OP was that high nutrient levels attract algae. My point is that we all have choices and we need not limit our choice to the methodology of poor nutrient levels only. I am at one end of the spectrum and you are at the other. But by seeing the differences each person can choose for himself/herself just how much singing and dancing they want to do and are not limited to your end of the spectrum alone. I think that's the heart of the issue and this is what I'm trying to illustrate.

Also, you seem to be attributing the stability of your tank to low nutrient levels and I believe that to be a miscorrelation. Whatever stability you have is strictly due to your lower PAR, not the lower nutrients, because there is a much higher probability of instability if you raised the PAR and kept the nutrient levels the save versus raising the nutrient levels and keeping the PAR the same. Low PAR lowers the nutrient uptake demand. If you were to add more nutrients right now what would be the results? I think I can predict that if you currently have say, small amounts of CO2 related algae then they would feed on the nutrients and you'd see an increase in their density. If you had small amounts of nutrient related algae you'd see an increase initially and then they would recede, followed by higher growth rates. Many people suffer the first case, such as thread or BBA. Then, if they are told to add more nutrients without their advisor identifying the algae they see an increase. They then erroneously concluded that nutrients unilaterally cause algae. The school of thought that considers nutrients a menace also worships other myths which conspire to prolong the agony.

High energy tanks do require that you stay on top of things. That's just how life is. I don't think that many people are attracted to the hobby by looking at plants that are barely eking out a living. Attraction, fantasy, imagination and desire will be stoked by the amazing. Isn't that why we have aquascaping in the first place? Why should stability be a more valued asset than beauty? So the easiest path to amazement and beauty clearly is appropriate application of CO2/nutrients. Is there a possibility of screwing things up? Of course, but so what? We're here to help you figure out the mistakes. I know exactly where the path to nutrient limiting leads. I've been down that road, and I know it's not where I want to be. Again, that's just a personal view. Choose a path, stability or amazement, but isn't it better to see where each path can lead in order to choose the right one?

Nutrients and CO2 are still quite poorly understood generally, so it's very easy for folks to be swayed by scare mongering. My purpose is to counter those arguments aimed against nutrients/CO2 and to show, first and foremost, that these components in and of themselves are not a causal factor in the problems that plague so many tanks. To focus away from nutrient paranoia and to think more carefully about the real causal factors such as lighting, filtration/flow, maintenance and so forth. The nutrient paranoia crowd are always at a loss to explain why our eutrophic tanks do not suffer algal blooms.

Now, you claim that your approach of limiting nutrients offers a more achievable objective. I say go to the Algae section of this forum and see how many gardeners suffer chronic poor health and algal outbreaks as a direct result of inappropriately limiting nutrient/CO2. Then count the number of those who solve their problems by then adding nutrients/CO2. Then, go to the Lighting section and count the number of threads that start off assuming one needs megawattage to grow plants. Again, I'm sure I sound like an insufferable extremist but I try to push the very boundaries of what is achievable with nutrients/CO2. What I learn along the way I'm happy to share.

Most simply don't understand the relationships between light/CO2/nutrients, or even the very basics of plant growth. But it can be explained, and I prefer to explain and to show the truth than to simply issue the same old dogmatic principles. I don't suggest that an unskilled gardener go over the top as I do, but what I am demonstrating is that you can go over the top because the "evil nutrients" as we have been led to believe is actually an ally, and that if I can get such results at the extreme end then dosing at more "reasonable" levels will likewise generate success. Nutrient paranoia is a disease of this hobby, a plague that hinders both artistic and botanical development. Knowledge and truth are the cure.


Cheers,

Hi all,
With thanks to Clive for the time he has spent on this post. Although I don't post very often, I've lurked on this forum for quite a while and I find much of the discussion here very interesting, and as the pictures earlier in this thread illustrate, what is possible truly amazing.

I think that as aquarium keepers we are always juggling light and nutrients, I'll include CO2 in this, (as well as as O2, nitrate etc.), but by adding CO2 and macro-nutrients (I'll assume for this that all micro-nutrient levels are in the range required for healthy plant growth) you are juggling a lot more balls, are lot higher, and unless you are a very skilled juggler, who fully understands the trajectories of all the balls, the potential for something to go wrong is much increased.

This is why I think the suggestion that for most algae ridden situations adding nutrients and CO2 will always help is dangerous, if things are out of balance, for me it is always better to return to a known datum (low nutrients, atmospheric CO2) rather than adding both nutrients and CO2 on the grounds that soon or later things will stabilise to a new datum. For example in the lab., I've got a state of the art nitrate probe, it is a thing of beauty but realistically it is of little practical value in telling me what the nitrate status of my tank water is. Additionally if I want to know how metal rich my water is I need to run a filtered sample through the Atomic Absorption Spectrophotometer, use colourimetry for orthophosphates and if I want to get an approximate value for how eutrophic a water sample is I need to run a 5 day BOD (although a conductivity meter will give me a quick approximation).

I am at a practical disadvantage compared to many of the members of this forum, in that I have never kept a high tech. aquarium., although I have worked with hydroponic tomato growing (including using propane burners to increase CO2 levels), and the phytoremediation of waste waters using Reeds, Willows, Water Hyacinth etc. However I don't think

Whatever stability you have is strictly due to your lower PAR, not the lower nutrients, because there is a much higher probability of instability if you raised the PAR and kept the nutrient levels the save versus raising the nutrient levels and keeping the PAR the same. Low PAR lowers the nutrient uptake demand.

Click to expand...

is right. I can't measure PAR (I don't have a "photon flux density meter") and whilst I have about 2w per(US)g, on most tanks, some of the tanks are under the glasshouse high pressure sodium grow-lamps (supplying about 15,000 lux at bench level) and are getting at least 20 watts per m2 for 12 hours a day (measured last night), even assuming that they receive no additional daylight (they actually receive daylight as well), the plant growth is slightly tighter for some of the floating plants (Pistia particularly), but otherwise things are fairly similar. This is because nutrient are still limiting, the analogy I would have would be with an Amazonian clear water river flowing from very old, very hard rocks, it has some vegetation growing but that is severely nutrient and CO2 limited (just atmospheric), but PAR is truly immense, somewhere in between 200 - 300w per m2. (PAR figures from <http://en.wikipedia.org/wiki/Insolation>.)

cheers Darrel

Hi Darrel,
Thanks for your input as well mate. As you noted, we're always happy to discuss these issues because we feel that they are fundamental to the success and enjoyment of the planted tank. Without a doubt there are pitfalls, and the road is even rockier when we increase the spectral energy levels. Honestly, you don't really need to be able to measure PAR to understand it's effects or to realize when your PAR is high or low, hence the generalized WPG rules of thumb. Of course, these rules are becoming outdated as we see developments in lighting technologies, T5, HQI, LED. We know from those hobbyists who do have PAR meters, that anything below about 2WPG of a typical T5 installation generates PAR values somewhere in the neighborhood of 100 micromoles or so at the surface with falloff at depth more or less commensurate with the inverse square law. Experience has shown therefore that generally, if you keep below this threshold, you can run a non-CO2 enriched tank using T. Barr's non-CO2 method with very much reduced nutrient loading and elimination of water changes.

To be fair, I should point out that there are brilliant examples of what can be achieved with non-enriched, such shown by Dusko in this thread Diana Walstead style tanks Dusko is very skilled at low tech tanks and he focuses on keeping the lighting levels low to solve many problems such as in the thread; Green Water - Dusko's lazy solution to the problem but certainly there is no need to run away from nutrients even in a non-enriched environment. There are very good reasons for the non-enriched approach, such as the low maintenance, low speed factors. As stated previously, if these issues are important then low tech should be considered.

If someone has never tried the high tech approach then it's very easy for them to assume that it's fraught with danger and that as you imply, that it's a frightful juggling act. The only reason this happens is when folks attempt it without understanding the principles if light/CO2/nutrients. The dosing principles are very simple as described in the dosing Tutorial EI DOSING USING DRY SALTS

All too often, would-be high tech hobbyists run out and spend lots of dough on high lighting and neglect to consider the more important aspects such as CO2, flow and nutrients. Then they get algae and the first thing they want to do is to complain about high nitrates/phosphates. I see this every day, so I'm familiar with all the nutrient hating arguments. That's why I'm adamant that the root of all evil in planted tanks is high PAR. Whether you can measure it or not, it's fairly easy to know when some has too much PAR.

When we advise the algae ridden hobbyist that the first thing to do is to lower the light they are appalled, because they had just spent all this money on fancy luminaries. So the misery continues until they can somehow improve the flow/distribution, CO2 and nutrient levels to match their PAR. I never had algae in my enriched tanks until I got high lighting, and I didn't solve my algae problems until I optimized CO2/nutrients/flow. Then it was necessary to understand the causes of algae, if in fact they were not caused by high nutrient loading, and that was a lot more difficult, because there are so many optical illusions. Some insights are discussed in Why dont nutrients cause algae?

Cheers,