... . In addition, the non-crystalline part of the surface of activated carbon, there are some oxygen tube ... instructions Material Preparation: 1, pebble: size: 40 ~ 80mm, 0.2m ³; 2, gravel: size: 5 ~ 15mm, 0.4m ³; ... closed the lower part of the filter tank refueling port; 2, first large-size filter into the jars ... way; 3, and then into the small particle size of pebbles, and pave the way; 4, finally into ...