# Growing Plants in a Piranha Aquarium



## harrykaa (Jan 10, 2005)

Hi Plant-Guru's,

I wrote down some thoughts concerning this problematic topic of keeping plants in a Piranha tank.
My intention or wish is to get going a discussion around this. So that as many aspects as possible could be covered.

I want to highlight, though, what does this actually concern:
- I do not mean to cover basic plantkeeping in a community tank,
- I do mean keeping plants in a tank where you have a shoal of Pygo's or a very big carnivorous fish, that eats a lot.
- I do not mean plantkeeping based on huge water changes and endless algae cleaning and regular replacing of dying plants,
- I want to discuss how people could be able to really grow plants with only minimal algae problems.

This obviously does not only mean tips how to feed fishes, tips how to fertilize plants, but also the importance of proper lightning, filteration etc. All of these are important.

So "no more lies", here are my thoughts:

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*Basics*
As this is a Piranha forum, the subject is to discuss growing plants in an aquarium where big carnivorous fish or even a shoal of fishes is kept. This adds a few prerequisites into this topic.

First and the most important point of all is that due to the carnivorous property of Piranhas, feedings add somewhat large burden to the water. Especially Pygocentrus species in a shoal consume a large amount of food on each feeding. The digestion of that means a large amount of feces. In addition to that, food leftovers from feeding frenzy cannot usually be all cleaned (siphoned) off. Heavy planting has also an impact on cleaning possibilities. Having said that we understand that nitrogen (NH4, NO3) and phosphorus (PO4) deficiency rarely exists in Pygocentrus tanks.

The second point is that Piranha species, although they commonly do not feed on plants or rip them, are big fishes. Their rough movements and occasional but also intentional biting favors tough and big plants.

*What is needed?*
In order to grow the plants need mainly three things: light, carbon dioxide and nutrients. Furthermore, to be accurate, plants do have demands for water temperature, pH and KH too. This has to be taken into account when choosing species.

_Light_
Fluorescent bulbs are the most common types, but also other bulbs are used. The light intensity (power output, lx value) and quality (wavelength, nm spectrum) is all that matters.

As plants have special photosensitive pigments (mainly chlorophyll a and carotene), the bulb type used should emit merely those wavelengths the pigments absorb. Thus a bulb emitting a lot of light green wavelengths is far more inefficient than a bulb emitting blue and red wavelengths. Most common, blue-green chlorophyll a absorbs at a wavelength of 400-450 nm (deep blue) and 650-690 nm (deep red); orange-red carotene absorbs blue-green light. Note that the emission peak of sun light is at 483 nm (light blue-green).

Another point to remember is that the common wattage figure (input power) is not so important. Some bulbs do consume energy but they emit in addition to visible light also invisible infrared wavelengths, which only has a warming effect. Yet there are great differences in commonly used fluorescent bulbs too (color temperature). Last but not least is the impact of the lamp structure. A clear silver reflector directs all the light downwards to the aquarium and is capable of increasing output power to the plants more than 100 % compared to a lamp with white interior background.

_Carbon dioxide_
If high light intensity and high balanced nutrients are offered, the concentration of carbon dioxide in the water column becomes a restricting factor, at least for fast growing plants. For this reason a pressurized CO2-system is recommended, when growing plants under high light environment. A commonly referred watt per gallon of aquarium water is on the other hand very obscure concept. A badly arranged lamp and bulb system of 3 watts (input) per gallon is not as efficient (output power) as a well arranged lamp and bulb system of 1.5 watts per gallon. In addition to that the distance from the bulb to the plant leaves varies (depth of a tank) too.

_Nutrients_
Plants are autotrophs. They can synthesize glucose and produce oxygen from carbon dioxide and water: 6H2O + 6CO2 + E > C6H12O6 + 6O2. Plants then use glucose as source for building material (cellulose). In order to build their structures plants also need nitrogen (for protein), phosphorus (for blooming), macronutrient potassium and micronutrients like iron, magnesium, manganese (for cell organs).

If only one of those is scarce, it becomes easily a restricting factor for the overall growth, but may also lead to abnormalities in coloration and structure. Overabundance of one or more of these elements has negative impacts too. Different species react in this situation differently. Some plants gain advantage over others while some species clearly suffer.

*Competition between species*
A general rule in biology (ecologic and evolutionary) is that those species exist in certain areas, which are best competitors there. Environment creates prerequisites, ability to adapt to it varies, some do not adapt at all. Some species excrete poisons and inhibitors against other species.

In aquarium and especially in a carnivorous fish tank, the environmental demands lead into situation where given plants are not the best adaptors while some unwanted ones are.

*Concerning the Algae*
As stated above environmental demands in a given aquarium may lead to a situation where algae are the best adaptors. This means they out compete the higher plants. The whole truth behind this is that you have created an aquarium mini ecosystem, which is most suitable for algae.

The most common reason to this is that nitrate and/or phosphate concentrations are too high compared to other parameters (micronutrients, light, carbon dioxide). In nature the eutrophication process due to human interference resembles this in the beginning. During the success better adapting species take over new species become abundant and dominant. In a closed system like aquarium usually the only new species available is an alga.

In aquarium you can lower the nitrate concentration even in bad cases by carrying out large and regular water changes. But at the same time also micronutrient levels drop and the relevant instability remains and leaves the algae an advantage.

The ecosystem in nature recovers more successfully. All the new species among the higher plants available competes for resources freely. Any one of them may take over and start using higher nutrient levels bringing about a new balance for this ecosystem. In many cases there still is no room for algae.

In an aquarium where eutrophication takes place, both the starting point and possibilities for new species to be introduced is very different. In the first place the hobbyist has chosen plants. These have very likely different abilities to adapt to eutrophication. And as the nutrient levels rise, there may simply not be a single higher plant capable of taking over the environmental changes. Thus some resources are left unused or only partially used. And it just happens that the unwanted algae do have the potential to do it.

*Aspects of balancing*
The higher plants are better competitors than any alga if the environment is ideal to them. In aquarium this usually is not applicable to all plants, as they are gathered or collected from different locations and ecosystems. The best practice is to choose only the plants that are adapted into high nutrient and somewhat low light environment.

In order to keep the environment suitable for the higher plants at all times, neither macronutrient nor micronutrient should become scarce or even worse end. If plants are able to consume even one important element totally, they immediately after that begin to suffer. Thus the growth collapses and problems begin.

A fully balanced aquarium ecosystem would have the same input (feeding) and output (removal of surplus plants). This, however, is possible to achieve only in theory. Plants are unable to use all accumulating nutrients and these will have to be removed by water changes. This way, however, all the elements in the water column are removed by the ratio of water changed creating unbalanced situation. It is then important to use necessary fertilization to regain the balance.

*********************

Regards,


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## s1edneck700 (Jan 5, 2006)

Very nice post. This thread will prove itself to be a valuable reference among members. My question has to do with the ambient fish waste in the tank. Will planted tanks metabolize these wastes and maintain a safe environment for inhabitants or will the aquarium still need frequent substrate vacuuming and maintenance. I realize that faster growing plants will consume more of these nutrients than others and these would be better suited for this purpose.


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## BigChuckP (Feb 9, 2004)

s1edneck700 said:


> Very nice post. This thread will prove itself to be a valuable reference among members. My question has to do with the ambient fish waste in the tank. Will planted tanks metabolize these wastes and maintain a safe environment for inhabitants or will the aquarium still need frequent substrate vacuuming and maintenance. I realize that faster growing plants will consume more of these nutrients than others and these would be better suited for this purpose.


In a planted tank it is best not to vacuum the substrate as you normally would. Instead take your siphon and wave it over the substrate to get the particles that are you laying on top and suck up easily. The rest of the particles will sink into the substrate giving the plants something to feed on. This is why a good aquatic planted will get "mulm" (basically waste and crap that collects in your substrate and filters) from an established tank and mix it in with the first layer of substrate. So to kind of come to an answer for you yes the plants will metabolize the waste but not all of it, which is why you should try and suck up the crap sitting on top of the gravel and do frequent water changes. As Harrykaa said piranhas produce large amounts of waste so your NO3 and PO4 will be high compared to say a neon tetra tank. Plants will absorb some of these nutrients but will not be able to absorb all of them.
To dose a planted tank with a shoal you should not have to dose PO4 or NO3, merely do wcs to keep the levels from skyrocketing.
I believe there are times though when you should actually vacuum the gravel, but I am not so sure when so I will leave that for someone else to comment on.


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## Winkyee (Feb 17, 2003)

Great post.


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## therizman1 (Jan 6, 2006)

Very nice post!


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## harrykaa (Jan 10, 2005)

BigChuckP said:


> In a planted tank it is best not to vacuum the substrate as you normally would. Instead take your siphon and wave it over the substrate to get the particles that are you laying on top and suck up easily.
> To dose a planted tank with a shoal you should not have to dose PO4 or NO3, merely do wcs to keep the levels from skyrocketing.
> I believe there are times though when you should actually vacuum the gravel, but I am not so sure when so I will leave that for someone else to comment on.


Yes pretty much like that.

Nitrates and phosphates gets so high, that no amount of plants can take care all of it. That's why regular water changes are a must. But you still should do it as little as necessary, because by water changes you also take out micronutrients and potassium, which have to be then redosed. Also tap water is usually by no means very good for aquarium purposes (chloramine, high pH...).

Siphoning only the surface of the gravel is what you should restrict it to. Otherwise you end up stirring root tablet contents into the water column and mix things badly.

An ideal case would be that you could dose micronutrients and Potassium with root pills and could be able to take care of nitrates and phosphates from the water column by the water changes, without removing the micronutrients and potassium. Could be somehow possible for the big root feeders.

Regards,


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## Winkyee (Feb 17, 2003)

harrykaa said:


> In a planted tank it is best not to vacuum the substrate as you normally would. Instead take your siphon and wave it over the substrate to get the particles that are you laying on top and suck up easily.
> To dose a planted tank with a shoal you should not have to dose PO4 or NO3, merely do wcs to keep the levels from skyrocketing.
> I believe there are times though when you should actually vacuum the gravel, but I am not so sure when so I will leave that for someone else to comment on.


Yes pretty much like that.

Nitrates and phosphates gets so high, that no amount of plants can take care all of it. That's why regular water changes are a must. But you still should do it as little as necessary, because by water changes you also take out micronutrients and potassium, which have to be then redosed. Also tap water is usually by no means very good for aquarium purposes (chloramine, high pH...).

Siphoning only the surface of the gravel is what you should restrict it to. Otherwise you end up stirring root tablet contents into the water column and mix things badly.

An ideal case would be that you could dose micronutrients and Potassium with root pills and could be able to take care of nitrates and phosphates from the water column by the water changes, without removing the micronutrients and potassium. Could be somehow possible for the big root feeders.

Regards,
[/quote]

I cannot get my nitrates or phosphates to climb. Even with minimal water changes of 25% per week as I did before plants. I dose daily with Nitrogen and excel,every few days with phosphorous, potassium and iron.


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## DiPpY eGgS (Mar 6, 2005)

^^that is because you have high light. The higher the light, the faster the plants suck down the nutrients, the more you have to dose them


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