Internal Aquarium Power Filters Interpet Model:PF3 Internal Filter please see the column in please see the column in the specification table regarding maximum replacement bulb length as these filter sets take only specific sized bulbs and anything longer than stated will not fit inside the system Optional mounting bracket can be purchased separately 4 PF2 500 Litres Per Hour (110 Gallons) Up To Approx 60cm (24 Inches) 45 90 Litres (10 20 Gallons) 9 Watts 23 The Biochamber which houses the bio media (included) is used for allowing beneficial bacteria to grow and thrive inside of the filter which helps to break down Ammonia levels in the tank