Complex sentence: Since 1857 it has been a spa, initially based on its climate and whey products, since 1930 it has been a Kneipp spa and since 1950 a Kneipp health spa.
Split into simpler sentences: Since 1857 it has been a spa, initially based on its climate and whey products. In 1930 it became a Kneipp spa and, in 1950, a Kneipp health spa.