Alphagrog

Alphagrog is a volcanic rock, proven to be a successful filter media as it ideal for the colonization of beneficial bacteria. The porous composition of this media allows the bacteria to multiply in abundance over a short period of time. The sharp edges of this natural rock require careful handling, and it is best situated in the last chamber of your filter, as you would not want your Koi rubbing against it! Remember to wear protective gloves whilst cleaning.