Ideal for starting and maintaining a freshwater tropical aquarium. Contains Stress Coat to make tap water safe - Stress Coat removes chlorine and chloramines and neutralises heavy metals. Contains Stress Zyme to help clean a dirty aquarium - Stress Zyme breaks down organic waste accelerates the development of the biological filter and improves its effectiveness. Each pack contains: 30ml Stress Coat and 30ml Stress Zyme (both treat 227L of water).