Keep the bottom of your garden pond sludge free with this natural treatment safe for fish plants and wildlife it uses natural bacteria to consume and break down wastesimply add 10ml of sludge remover to a 250ml bucket or watering can filled with pond water and apply to the pond working from the edges inwards reapply after one month then every 2 months for perfect results all year roundthe bottle contains 500ml which is sufficient for up to 12 500 litres fountain cleanerp17321 and algae