The coarse structure of this chemically purified VijverTechniek filter lava chunks makes it a particularly suitable filter substrate for a wide range of pond filters. This porous material has many holes, in which billions of microorganisms will settle, which has a cleansing effect on your pond water. Just fill the included filter net with lava chunks, flush it with water several times, and then place it in your filter system.

• 5000 ml treats 3000 L pond water