Farská kyselka is a freely accessible mineral spring above the former excursion restaurant and guesthouse Nimrod in the mineral water springs area around Mariánské Lázně in the Cheb district. The spring got its name from the name of the forest, which in the past belonged to the local parish with its headquarters in nearby Rájov. The spring is located in the Slavkovský Forest in the spring of the Mnichovský stream about 4.5 km north of Mariánské Lázně. It springs at an altitude of 767 m and is the highest captured mineral spring in the Slavkovský Forest Protected Area. The spring is collected by a shallow well, where the excess water flows down a gutter colored by the iron salts contained in the mineral spring. The mineral spring is undoubtedly one of the tastiest in the area around Mariánské Lázně. The water from Farská kyselka flows into a small ochre-colored lake.
At first glance, an unattractive pond is home to a rare species of diatom
The bedrock is formed by the rocks of the Marianske Lazne metabasite complex, the largest body of metamorphosed basic rocks in the entire Bohemian Massif. Along the fault lines in the rock massif, mineral waters and gases penetrate to the surface here, as echoes of Tertiary and in places even Quaternary volcanic activity.
About 100 meters west of Farská kyselka, other small springs of mineral water and gases were observed in a drainage ditch in the forest. These geological manifestations are most prominent in the Smraďoch nature reserve, about 500 m southwest of Farská kyselka.The interesting endemic diatom Pinnularia ferophila lives in the lake into which the mineral water flows. It was able to adapt to the iron-rich environment of mineral springs, and until 2007, the lake by the spring was the only known place in the world where this diatom occurs. Later, the occurrence of this diatom was confirmed in Slatinná kyselka near Číhaná and in Kyselecký hamr.
The original wooden gazebo above the spring was built around 1896, the bricked square shaft with an octagonal wooden frame dates from the beginning of the Mariánské Lázně spa industry. As early as 1909, there were thoughts of bringing it to Mariánské Lázně and using Farská kyselka for carbon dioxide baths. More recent efforts date back to the 1980s, but the plans were not implemented. In 2011, the gazebo was repaired, and a small shelter for tourists was built nearby. The mineral water can be tasted at the source.The temperature of the spring is relatively constant, around 7 °C, the total mineralization is quite low, approximately 440 mg/liter. The dissolved carbon dioxide content is, on the other hand, high and reaches 2,300 to 2,750 mg/liter, which gives the mineral water high effervescence and a pleasant taste. The mineral water has an increased magnesium (Mg) content of 51.7 mg/liter. The pH value is 5.5. The yield is quite high, according to measurements from March 2019 it is 20 liters/min.
Photo 1-3: Farská mineralspring