Alder cones are rich in active substances (such as tannins) and renowned for their anti-bacterial and fungicide effect. The cones are often used in aquascaping and aquarium design especially in biotope aquariums. Black alder trees are typically found close to natural waters and in swamps in Europe.
Alder cones lower the pH value of the aquarium water (making it slightly acidic). They release humic substances and this also gives a slightly brownish colour to the aquarium water.
Alder cones provide a substrate for biofilm that shrimps and snails graze on. They also improve the overall well-being of your aquarium inhabitants and help in certain activities (e.g. shrimp moulting).
Alder cones are typically between 1 and 2 cm in size.