PhytaGen P1

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Phosphorus supplement for planted aquaria

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PhytaGen P1 is a phosphorus supplement for aquaria.

The use of PhytaGen P1 is advisable in the cultivation of fast-growing aquatic plants and / or where their phosphorus requirement can not be guaranteed by the organic substances introduced by other routes (eg through the bottom or the introduction of feed for fish).

PhytaGen P1 provides phosphorus in the form that can be best assimilated by plants: the anion orthophosphate (PO43-).

In order to allow the best development of plants, it is important to highlight how nitrogen and phosphorus should always be present in water in a correct reciprocal relationship (see below in the directions of use).
Since however there may be cases of altered balance between these two elements in the tank and consequent need to dose them separately, alxyon has preferred to provide separate nitrogen and phosphorus supplements.


PhytaGen P1 is highly concentrated and contains 4892.1 mg/l of phosphorus.
For ease of understanding we emphasize that this is the same amount of phosphorus present in 15000 mg / l (15 g/l) of phosphate (PO43-.)



Come ln1 duraturo Nell arco della settimana
Col calcolatore semplicissimo da dosare soddisfatto.


Macro per eccellenza

Eccellente integratore di fosfati, non contiene organico, 1 ml su 15 litri additiva realmente 1 mg/l di PO4


Perfetto !

Lo trovo davvero un’ottimo integratore di Fosfo. La consegna rapida e l’assistenza eccellente ! Le istruzioni del dosaggio riportate sull’etichetta, sono davvero chiare e semplici. Appena inserito ho riscontrato una buonissima reazione da parte delle piante. La Rotala Macrandra Red ha iniziato a crescere in maniera esponenziale, cosa che non a cadeva con altri integratori. Sono molto soddisfatta sotto ogni aspetto, grazie ai titolari e complimenti !


Phytagen P1 should be dosed when necessary (ideally once a week); in such amount as to bring/restore phosphate/phosphorus concentration to the set target value.
Taking anyway into account the fact that 1 ml of PhytaGen P1 in 15 liters of water increases phosphate (PO43-) by 1 mg/l (equal to 0.326 mg/l of phosphorus).

Choice of the phosphate/phosphorus target value

The target value for phosphate/phosphorus varies according to the quantity of vegetables present in the tank and their growth rate (influenced by the amount of light, CO2 and other nutrients).

Later we will summarize this parameter with the term "Vegetal Metabolism" (abbreviated as VM) and we will exemplify distinguishing between:

• High VM: high nutrient consumption; due to the presence of many rapidly growing plants.
• Average VM: average nutrient consumption; due to a reasonable presence of plants and / or their average rapid growth
• Low VM: low nutrient consumption; due to the presence of a few plants and/or a low growth rate.

Obviously all the intermediate gradations remain possible.
Depending on the aforementioned VM, alxyon recommends that you use the following target values ​​for the phosphate:

• High VM: 1.5 mg/l of phosphate from PhytaGen P1
• Average VM: 1 mg/l of phosphate from PhytaGen P1
• Low VM: 0.5 mg/l of phosphate from PhytaGen P1

The dosage of PhytaGen P1 must therefore be performed keeping into account the phosphate target chosen for the specific tank (depending on the VM of the same) and carried out with the aim of bringing the concentration of phosphate back to the target previously set.

The dosage must take into account the fact that 1 ml of PhytaGen P1 in 15 liters of water increases phosphate (PO43-) by 1 mg/l (equal to 0.326 mg/l of phosphorus).

Dosing procedure

In general, it is recommended that the dosage of PhytaGen P1 be taken weekly once the water is changed and after the new water has been introduced.
In this case the dosage procedure is as follows:

• Make the recommended water change (20-25% of the total).

• Re-inject the changed and rebuilt water with PhytaGen S1 Planta salts.

• Wait until the salts have completely dissolved and the water has returned perfectly clear.

• Measure the concentration of phosphate in water.

• Dose the amount of PhytaGen P1 necessary to bring back to the target established according to the VM of the tank.

Once the composition of the tank and the speed of growth of the vegetables have settled, it is possible to assume with a good approximation that the consumption remains constant and the quantity already known can be measured without having to necessarily measure the concentration of the phosphate (which is however recommended ).

By way of example, based on our experience, we report the following possible consumption:

• High VM: 1.5 mg/l of PhytaGen P1 phosphate per week
• Average VM: 1 mg/l of PhytaGen P1 phosphate per week
• Low VM: 0.5 mg / l of PhytaGen P1 phosphate per week

Based on these estimated consumption, the dosage can be assumed without the need to measure the phosphate; But, as mentioned, alxyon's recommendation is to proceed as detailed in the points above.

For example:
In general, for an aquarium with a good presence and vegetal growth (MV Medium), the dosage is recommended for the first week at a rate of 6.7 ml per 100 liters of aquarium water.
This dose increases the phosphate by 1 mg/l.
From the following week onwards, on the other hand, it will be dosed according to the consumption of the tank; or what is necessary to bring/maintain the concentration of phosphate around 1 mg/l.
In order to obtain the best results it is also very important to dose the phosphorus in a balanced manner compared to nitrogen (see "Redfield Ratio" in the technical notes).

In particular, a ratio of about 7: 1 between nitrogen and phosphorus should be maintained.
Equivalent also to maintain a weight ratio between nitrate (NO3-) and phosphate PO43-) of about 10: 1.

Based on this principle PhytaGen P1 should therefore be used in conjunction with PhytaGen N1 according to the respective directions of use. In particular, the combined use of PhytaGen N1 at the same dosage guarantees the combined nitrogen and phosphorus supplementation in the correct N: P ratio of 7: 1 (ratio NO3-: PO43- of 10: 1)

Please find hereafter a dosage calculator to be used on mobile phones.
Just select the relevant product (M1, M2, N1, P1, S1) from the top tabs, insert the data requested and the program will calculate the amount of product to be dosed.

What is the optimal phosphorus concentration in aquarium?

This question can not have a unequivocal answer.
As we already detailed in the tab regarding the usage, this depends mainly on the amount of plants and their growth rate.

The latter being influenced by various factors, such as the nutritional status (mainly the amount of dissolved CO2) and light irradiation.

In general, the suggestion is to follow the suggested dosages, keeping phosphorus concentrations ranging from about 0.16 to about 0.33 mg/l (equivalent in terms of phosphate to 0.5 mg/l for low vegetal metabolism aquariums and up to 1.5 mg/l for high vegetal metabolism aquariums) and not exceeding 0.65 mg/l (equivalent to 2 mg/l of phosphate) for a single administration.

All of this, always trying to keep a good ratio to nitrogen, as detailed in the technical notes, regarding the description of the "Redfield Ratio".

Does phosphorus causes algae?

The idea that phosphorus may cause algae in the aquariums arose from an article (Control of algae in planted aquariums) of two Canadian aquarists: Conlin and Sears.
In their article they reported the results of some experiments conducted by them in their aquariums.

In these experiments the two authors noted how by eliminating the phosphorus from the water (but leaving it confined in the substrate) it was possible to maintain a good growth of the plants while obtaining a reduction or disappearance of algae.

Where or when water was supplied with phosphorus, algal growth resumed.

In general, in these cases we must always consider the validity of the Liebig law.
That is the fact that the growth of the vegetals (plants and algae) is limited by the lack even one of the indispensable elements (whatever).

When this element is then administered again, the growth of the vegetals (plants and algae), no longer being limited, immediately resumes.

Therefore limiting an essential element (such as the aforementioned phosphorus) in water, it will be possible to limit the growth of those plants that obtain their nourishment exclusively from water.
Algae and floating and epiphytic plants essentially.

On the other hand, the growth of those plants that are able to obtain that nutrient by the roots from the substrate will not be compromised.

But this is valid for each of the essential elements for plants.
Phosphorus is still an excellent candidate from this point of view because it is an element (macroelement) that is used in fair quantities and because it is an element that, with appropriate strategies, is able to contain quite well in the substrate in an insoluble form, avoiding that it disperses in water.

It must be said, however, that in plant aquariums commonly found today among enthusiasts, with many plants growing rapidly and which are then pruned and replanted often (having to replenish the root system every time), it is not possible to maintain rapid growth and optimal only with the nutrients in the substrate and must provide quite substantial doses of all the essential elements directly in water.

Hence the theory/strategy of Conlin and Sears has had a short life, showing itself not entirely correct in motivations/conclusions and impracticable in the implementation; as a matter of fact already surpassed after about ten years from its formulation.

The conclusion is therefore: No; Phosphorus does not cause algae.
Just as algae are not caused by any of the essential mineral elements in particular; being an algal proliferation to be sought essentially in the presence of organic material in the tank, in a non-optimal growth of the higher plants present (bad competition with algae) and in the imbalance between nutrients (see Redfield Ratio).

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