TetraTec IN filters contain a foam sponge, through which aquarium water is recirculated. This sponge acts as both a mechanical filter, straining out particles of solid waste, and as a biological filter. As water is pumped out of the filter, it draws in air through a 'venturi' attachment, thus helping to re-oxygenate the water.

IN 400 Tetra tec	400l/ph	24 inch aquaria
IN 600 Tetra tec	600l/ph	36 inch aquaria
IN 800 Tetra tec	800l/ph	48 inch aquaria
IN 1000 Tetra tec	1000l/ph	60 inch aquaria