Alfagrog filter media
Alfagrog has been used for years as a fish pond filter media. A single litre of Alfagrog will cater for a pond of 1,000 litres from a biological point of view.
Its large surface area makes Alfagrog ideal for growing filter bacteria. The more bacteria in the pond filter the better the pond water quality will be. These bacteria transform toxic chemicals in the pond water secreted by the fish into plant fertilizer suitable for pond plants.