Complex sentence: Wet/dry filters rely on the growth of bacteria, therefore, use of this system in a new tank requires care, including allowing the water to filter through the tank for several weeks in the presence of a food source for the bacteria.
Split into simpler sentences: Wet/dry filters rely on the growth of bacteria, therefore, use of this system in a new tank requires care. This includes letting the water filter through the tank for several weeks in the presence of a food source for the bacteria.