Mr Koizumi ??Filter Start?? is a mix of selected Nitrosomonas and Nitrobacter bacteria that actively break down ammonia and nitrite at a temperature from 8?C. Regularly adding these bacteria to the pond filter increases biological action, optimally removing pollutants like ammonia and nitrite and breaking down organic material, thus preventing filter clogging.? *Concentrated formular*- MR KOIZUMI ??FILTER START ?? contains around 1 BILLION colony forming units per ml making it one of the highest quality pond filter starters available!