A very cost effective starter pack including all the filter pads and media you need for your professionel 3 filterthe set containsehfimech x 4 litres removes all coarse and fine dirt particles from the watersubstratpro x 8 litres for quick colonisation of bacteria and faster decomposition of toxinscoarse filter pad x 1 large pore sponge giving bio mechanical filtration and even water flow throughfine filtration x 1 before the water re enters your aquarium fine dirt particles are trapped i