The pre-filter or intake sponge is a simple foam cylinder that is designed to slip over the intake tube of hang-on-back (HOB) and canister filters. The filter intake tube often has large openings that allow sizable objects to get sucked up by the filter, potentially ruining the motor, so use a pre-filter sponge to help prevent baby fish, dwarf shrimp, little snails, plant leaves, fish food, and other debris from entering the filter. (depending on filters suction, and size of animal, tiny fry/shrimp/snails can still get through in some cases)
An intake sponge also provides valuable surface area to grow beneficial bacteria, which purify waste chemicals in the water and make it safe for your fish to live in. Finally, it adds mechanical filtration that extends the life and efficiency of your filter media.
Specifications:
Mini:
Intake hole: 0.5 inches
Diameter: 1.25 inches
Length: 2.75 inches
Pore Size: approximately 25 ppi
Medium:
Intake hole: 0.5 inches
Diameter: 2.5 inches
Length: 3 inches
Pore Size: approximately 25 ppi
Large:
Intake hole: 1.25 inches
Diameter: 3.5 inches
Length: 5.5 inches
Pore Size: approximately 20–25 ppi
