Purity: Concentration of Sidr and Camphor in Ghusl Water
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 539:
The amount of sidr leaves and camphor in the water must not be so great that they turn the water into mixed (muḍāf) water, neither must the amount be so little that it cannot be said that sidr leaves and camphor have been mixed in the water.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)