HTH Clear-4-Weeks is non-stabilised chlorine that sanitises your pool from bacteria and prevents algae. This monthly sanitiser contains four weekly doses of chlorine that keep your swimming pool water clean, clear and sparkling blue. One pack of HTH Clear 4 Weeks is suitable for 50,000 litres of water or less. HTH Clear-4-Weeks should be stored away from small children and pets. If skin contact is made, rinse with for water for at least 15 minutes. Seek medical attention immediately if inhaled or ingested. Water is safe for swimming approximately six hours after use.