Persicaria sp. 'Sao Paulo'

Aquarium suitability: yes
Usage: Accent (red), Semi-emersed plant for open tanks, Background, Midground
Difficulty: medium
Growth: fast
Light: medium to high 
Temperature tolerance: 18 to 30 °C
Optimum temperature: 23 to 27 °C
Carbonate hardness: 0 to 14 °dKH
pH value: 5 to 7 pH 
Carbon dioxide (CO2): 20 to 40 mg/l
Nitrate (NO3-): 10 to 50 mg/l
Phosphate (PO43-): 0.1 to 3 mg/l
Potassium (K+): 5 to 30 mg/l
Iron (Fe): 0.01 to 0.5 mg/l

Persicaria (Polygonum) sp. 'Sao Paulo' is a fantastic new aquarium plant from Brazil. At the moment, the correct species name of this knot weed is still in the dark. When kept in the right conditions, this is probably the most intensively coloured plant species currently available for aquarium.

Persicaria (Polygonum) sp. 'Sao Paulo':
- (under strong light) the leaves are red, more or less overall along the entire stem
- Colour: intensive magenta
- the youngest leaves curve downward
- leaf form: more or less lanceolate
- this plant always grows strictly upright, its lateral shoots are also upright and don't really grow at an angle at all

Persicaria sp. 'Sao Paulo' is no plant for low-light tanks, however, it grows exceedingly well in the type of aquarium with CO2 injection and strong lighting, which has gained popularity during the last years. It is especially suitable for tank layouts that have been designed for Tonina fluviatilis, Eriocaulon or Syngonanthus species. To further maximal colouration and healthy growth, direct light coming from metal halide, compact or T5 lamps is recommendable. It is also important to fertilize with ample amounts of iron, and to maintain a phosphate concentration of 1 mg/l or above.

This knot weed may be very suitable for aquascapes, however, it is a challenging plant anyway, as planting it in too large a group is a very real danger. Some few stems are usually more than enough! P. sp. 'Sao Paulo' has the typical stiff, vertical growth habit of a knot weed, whereas a small, uneven number of stems has proven most effective.
A background of light green plants lets P. sp. 'Sao Paulo' stand out especially.

It is often overlooked that this knot weed also does well when cultivated emersed in a palladium or something comparable. There it shows an intensive wine red to purple colour. Its land form often develops flower stems (which may also appear in the submersed form, although less frequently), that add interesting detail to the layout.