Grünská kyselka, Mineral spring in Louka, Czech Republic

Grünská kyselka is a mineral spring on the left bank of the Kyselka stream northwest of Louka, in the Slavkovský les protected area. Its water rises through serpentine of the Mnichov amphibolite belt, giving it a magnesium content usually cited at 290 mg per litre. The original outlet lies in a fenced well area; the public tap is a covered shelter outside it.

Local people likely knew the spring by the 17th century. After the Beaufort-Spontins bought the Bečov estate in 1813, Count Jindřich Beaufort-Spontin had the outflow improved and the spring was briefly called Arnoštin pramen after his second wife. In 1893 the Louka farmer Engelbert Zuleger bought the spring site and had the water analysed; from 1899 he bottled it as Zulegerova minerálka, exporting to Vienna, America and Japan. In 1928 the Löser couple built an octagonal pavilion over the spring.

The spring gave its name to the nearby settlement: Louka was known in German as Grün, hence Grünská kyselka. Count Jindřich Beaufort-Spontin briefly called it Arnoštin pramen after his second wife. From 1899 the water was sold as Zulegerova minerálka, and in the 1930s guests came by bus from Mariánské Lázně to the Café Almbrünnl beside the spring.

The spring is reached by a forest path branching from the road between Nova Ves and Louka, leading to a public pavilion. Visitors should wear sturdy shoes for the forest walk and bring containers if they want to collect water.

The spring is often mistaken for the source of the bottled water Magnesia, but it is only one ingredient: since 1991 Karlovarské minerální vody has drawn water from new boreholes nearby and mixes it with water from other boreholes in the serpentine area around the Kyselka, Mnichov and Prameny streams. The original spring mouth lies inside a fenced wellfield closed to the public; a pipe from one borehole carries an overflow outside the fence to a covered pavilion where anyone can fill a bottle.