Aquascape Cold Water Beneficial Bacteria contains 7 pure strains of concentrated beneficial bacteria that work quickly cleaning and balancing your water garden. This Cold Water Beneficial Bacteria works at temperatures below 50F or 10C. Water gardens are enclosed ecosystems, which sometimes factors like fish load, uneaten fish food, organics such as leaves, sludge and unwanted debris may disrupt the balance. Aquascape Cold Water Beneficial Bacteria contains a specific combination of bacteria that are most effective at doing two jobs- reducing organic material such as leaves and pond sludge and reducing ammonia, nitrite and excess nutrients such as phosphate that are known to cause poor water quality and unsightly water conditions.