The Bak-Pak 2 Bio-Filter is the second generation external, hang on the back, combination Protein Skimmer and Biological Filtration unit from CPR. The Bak-Pak 2, like the original, is designed for tank sizes up to 60 gallons. Water first enters the Protein Skimmer column from the aquarium and then flows through the biological chamber filled with Bio-Bale filtration media before returning to the aquarium.
