Chapter 1: Assessing the true status of plants/animals is not as easy as it first appears
1) First premise: The overall condition of an organism can be assessed by its external form or by its internal contents.
--- with the content being [with few exceptions] more important than the form, because the specific form is [in most cases] based on the content
--- the content has more predictive value than the form
--- there are exceptions when form may override content: e.g. external mechanical damage [e.g. due to too strong water flow or leaf nibbling by snails/fish] or algae/cyanobacteria infestation of plants [not due to their poor condition, but simply due to uncontrolled algal overgrowth]
2) Second premise: Most aquarists judge the condition of their plants/animals by their external form.
--- typically by growth rate, size, coloration, absence of external deformities or absence of algae (in plants) or by liveliness/vigor, appetite and ability to reproduce (in animals)
3) Result: Most aquarists judge the condition of their plants/animals by secondary (and therefore potentially misleading) measures.
Examples (possible combinations) of external and internal organism conditions that can theoretically occur:
A) good form + good content
B) good form + poor content
C) poor form + good content
D) poor form + poor content
It is important to realize that we do not know the inner content (i.e. the current state of metabolic processes) and we do not have many options to find out. However, if we don't know the second (and more important) part of the equation, we can't be sure of the outcome either!
PS: Many times we do everything we can to achieve the image we want to see in our aquarium, even at the cost of "torturing" its inhabitants. We are not interested in what our plants (or animals) like, but we have elevated our aesthetic preferences to a standard (measure) by which to judge their condition. If a plant fits our aesthetic preferences, then we declare it "perfectly healthy" (i.e. in optimal condition), without acknowledging the possibility that it may be in state B (i.e. good form + poor content).
Chapter 2: So how do we properly assess the condition of our plants/animals to be as close to reality as possible, even if we can't see inside them?
1) Take inspiration from nature (with its laws), use common sense and do not use extreme methods (typically for example unnaturally high nutrient doses)!
A number of scientific studies have presented the evidence that unnaturally high concentrations of certain nutrients (or inappropriate ratios) can be harmful to different plants [under certain circumstances].
--- For example, some studies have suggested that CO2 concentrations above 40 ppm can have a narcotic effect on some plants. Other specialized or scholarly literature recommends 10-20 ppm as the maximum recommended long-term CO2 concentration for aquatic organisms, as higher concentrations can lead to various internal metabolic and physiological disturbances. If it is true that we should not expose aquarium animals to CO2 concentrations above 20 ppm, but we still expose them to such concentrations [long term], then what else can we call it but deliberate torture?
Such high nutrient concentrations [that are used and recommended by some aquarists] are not commonly found anywhere in unpolluted natural waters.
--- While this does not mean anything in itself, it is good to realize that if something is not commonly found in nature (i.e. plants and animals do not normally encounter it), then it is highly likely that they have not developed any mechanisms to cope with such unnatural concentrations (= extremes), or they do have some mechanisms, but they are not built for such extreme situations (i.e. extreme nutrient concentrations). This assumption is logical and central, and is supported by a number of scientific studies.
If we cannot be 100% certain that the concentrations of nutrients (or other agents) we use are truly harmless to our plants/animals, then it is certainly reasonable to stick to such concentrations and mimic conditions that are as close as possible to the natural ones in which the plants/animals in question have thrived for thousands of years (and are thus perfectly evolutionarily adapted to).
While using extremely high doses of nutrients may result in "bigger, faster growing and more colourful" plants, it may also place an unnatural strain on their internal metabolism (in other words, stress them continuously).
--- I have unfortunately met aquarists who cannot admit this possibility. They believe that "good form" is automatically unquestionable proof of overall optimal condition.
2) Continue to evaluate plants/animals by external form, but with the understanding that it is not the only (and obviously not the most important!) measure.
3) If you can afford it, also perform internal content analysis (e.g., dry matter nutrient content can be a relatively useful indicator).
4) Conduct comparative tests.
--- Why use extreme methods when similar results can often be achieved with much more moderate methods that are much gentler on aquarium plants/animals?
--- Take a look at my latest experiment for example, where I only use something like ~11 ppm CO2 (+ very low doses of other nutrients) and think about whether it is really necessary to use that much more.
A few final notes on algae:
Sometimes we use to say that "algae only attack unhealthy plants". But how can we know that a plant infested with algae is unhealthy if we are only able to judge its health by its external form?
Of course, it is possible (even likely) that a fast-growing leaf is a worse surface for algae to attach to than a slow-growing (or stagnant) leaf. Of course, a healthy organism is generally more resistant to disease than an unhealthy one. But does this always and everywhere (in all circumstances) apply? Will a plant that grows in an environment perfectly suited to algae successfully resist it? And will it resist them even if we remove all algae eaters (snails/shrimps) from the aquarium, cancel filtration, stop using the surface skimmer, stop regular maintenance and water changes? I highly doubt it. On the contrary, I am convinced that if you remove all the means that help keep algae at bay from the aquarium, then the healthiest plant will not be able to resist them. In an aquarium with no filtration and no bunch of shrimps, algae will simply appear after a month, even if you crawl on hands and knees over broken glass. And regular maintenance and weekly 50% water changes won't help either. On the other hand, with an army of shrimps I don't have to do anything and the algae will never show up.
I know this topic will probably be a bit controversial for some, but I wanted to bring it up here anyway, so that we can at least think about it. I am not imposing my views here on anyone. Advocates as well as opponents of my views will surely find many other arguments to support their views (which is certainly a good thing).
1) First premise: The overall condition of an organism can be assessed by its external form or by its internal contents.
--- with the content being [with few exceptions] more important than the form, because the specific form is [in most cases] based on the content
--- the content has more predictive value than the form
--- there are exceptions when form may override content: e.g. external mechanical damage [e.g. due to too strong water flow or leaf nibbling by snails/fish] or algae/cyanobacteria infestation of plants [not due to their poor condition, but simply due to uncontrolled algal overgrowth]
2) Second premise: Most aquarists judge the condition of their plants/animals by their external form.
--- typically by growth rate, size, coloration, absence of external deformities or absence of algae (in plants) or by liveliness/vigor, appetite and ability to reproduce (in animals)
3) Result: Most aquarists judge the condition of their plants/animals by secondary (and therefore potentially misleading) measures.
Examples (possible combinations) of external and internal organism conditions that can theoretically occur:
A) good form + good content
1) External form = good
2) Internal content = good
3) Overall condition = optimal
B) good form + poor content
1) External form = good => e.g. disturbed internal metabolism but not reflected in external appearance
2) Internal content = bad
3) Overall condition = suboptimal
- Example (in fish): higher concentration of harmful substances in internal organs, nephrocalcinosis (deposits in kidneys), higher mortality rate of fry, shorter lifespan, overall higher stress levels etc.
- Example (in plants): higher concentration of harmful substances or too high concentration of nutrients in the tissue, "obesity", increased excretion of organic exudates, mild poisoning (narcotic effect), different colouration - richer or paler (paradoxically considered desirable by aquarists and as evidence of optimal condition)
C) poor form + good content
1) External form = bad => e.g. external deformation due to purely external damage (without serious impact on the overall state of internal metabolism)
2) Internal content = good
3) Overall condition = suboptimal
D) poor form + poor content
1) External form = poor => e.g. disturbed internal metabolism which is also reflected in the external appearance
2) Internal content = bad
3) Overall condition = suboptimal
It is important to realize that we do not know the inner content (i.e. the current state of metabolic processes) and we do not have many options to find out. However, if we don't know the second (and more important) part of the equation, we can't be sure of the outcome either!
PS: Many times we do everything we can to achieve the image we want to see in our aquarium, even at the cost of "torturing" its inhabitants. We are not interested in what our plants (or animals) like, but we have elevated our aesthetic preferences to a standard (measure) by which to judge their condition. If a plant fits our aesthetic preferences, then we declare it "perfectly healthy" (i.e. in optimal condition), without acknowledging the possibility that it may be in state B (i.e. good form + poor content).
Chapter 2: So how do we properly assess the condition of our plants/animals to be as close to reality as possible, even if we can't see inside them?
1) Take inspiration from nature (with its laws), use common sense and do not use extreme methods (typically for example unnaturally high nutrient doses)!
A number of scientific studies have presented the evidence that unnaturally high concentrations of certain nutrients (or inappropriate ratios) can be harmful to different plants [under certain circumstances].
--- For example, some studies have suggested that CO2 concentrations above 40 ppm can have a narcotic effect on some plants. Other specialized or scholarly literature recommends 10-20 ppm as the maximum recommended long-term CO2 concentration for aquatic organisms, as higher concentrations can lead to various internal metabolic and physiological disturbances. If it is true that we should not expose aquarium animals to CO2 concentrations above 20 ppm, but we still expose them to such concentrations [long term], then what else can we call it but deliberate torture?
Such high nutrient concentrations [that are used and recommended by some aquarists] are not commonly found anywhere in unpolluted natural waters.
--- While this does not mean anything in itself, it is good to realize that if something is not commonly found in nature (i.e. plants and animals do not normally encounter it), then it is highly likely that they have not developed any mechanisms to cope with such unnatural concentrations (= extremes), or they do have some mechanisms, but they are not built for such extreme situations (i.e. extreme nutrient concentrations). This assumption is logical and central, and is supported by a number of scientific studies.
If we cannot be 100% certain that the concentrations of nutrients (or other agents) we use are truly harmless to our plants/animals, then it is certainly reasonable to stick to such concentrations and mimic conditions that are as close as possible to the natural ones in which the plants/animals in question have thrived for thousands of years (and are thus perfectly evolutionarily adapted to).
While using extremely high doses of nutrients may result in "bigger, faster growing and more colourful" plants, it may also place an unnatural strain on their internal metabolism (in other words, stress them continuously).
--- I have unfortunately met aquarists who cannot admit this possibility. They believe that "good form" is automatically unquestionable proof of overall optimal condition.
2) Continue to evaluate plants/animals by external form, but with the understanding that it is not the only (and obviously not the most important!) measure.
3) If you can afford it, also perform internal content analysis (e.g., dry matter nutrient content can be a relatively useful indicator).
4) Conduct comparative tests.
--- Why use extreme methods when similar results can often be achieved with much more moderate methods that are much gentler on aquarium plants/animals?
--- Take a look at my latest experiment for example, where I only use something like ~11 ppm CO2 (+ very low doses of other nutrients) and think about whether it is really necessary to use that much more.
A few final notes on algae:
Sometimes we use to say that "algae only attack unhealthy plants". But how can we know that a plant infested with algae is unhealthy if we are only able to judge its health by its external form?
Of course, it is possible (even likely) that a fast-growing leaf is a worse surface for algae to attach to than a slow-growing (or stagnant) leaf. Of course, a healthy organism is generally more resistant to disease than an unhealthy one. But does this always and everywhere (in all circumstances) apply? Will a plant that grows in an environment perfectly suited to algae successfully resist it? And will it resist them even if we remove all algae eaters (snails/shrimps) from the aquarium, cancel filtration, stop using the surface skimmer, stop regular maintenance and water changes? I highly doubt it. On the contrary, I am convinced that if you remove all the means that help keep algae at bay from the aquarium, then the healthiest plant will not be able to resist them. In an aquarium with no filtration and no bunch of shrimps, algae will simply appear after a month, even if you crawl on hands and knees over broken glass. And regular maintenance and weekly 50% water changes won't help either. On the other hand, with an army of shrimps I don't have to do anything and the algae will never show up.
I know this topic will probably be a bit controversial for some, but I wanted to bring it up here anyway, so that we can at least think about it. I am not imposing my views here on anyone. Advocates as well as opponents of my views will surely find many other arguments to support their views (which is certainly a good thing).
