Recommended dosage is 65 ml. per 1000 litres of tank volume, depending on the pollution grade. Follow the table to find the correct dosage for your water volume. *TankSafe is consumed in the process of neutralising bacteria and any organic material, therefore, some tanks may require an initial shock dose. Dosage is dependent on the level of bacteria in the tank. The tank should be dosed with TankSafe until the test strip (sold separately) registers the presence of residual TankSafe. Multiple shock doses may be required initially.