A. Aqua Soil is made of natural soil and the aquarium water may become cloudy if fine soil particles are stirred up. This symptom may easily occur if Aqua Soil is washed just as we do for gravels before placing in an aquarium and if stones and driftwood are moved many times after the aquarium tank is filled with water. Doing this crushes the Aqua Soil grains and may result in cloudy water. Avoid washing Aqua Soil before placing on the substrate and arrange the stones and driftwood before pouring water into the tank. The water also becomes cloudy if the substrate soil is stirred up when the water is poured in the tank. Prevent this by placing a plastic sheet or plate on the substrate until the aquarium has a certain amount of water. In the event where the aquarium water is extremely cloudy after filling the tank with water, remove and refill the water to eliminate cloudy water before starting to operate the filter. Be sure to operate the filter only after the water has become clear. If the filter is used when the water is cloudy, the cloudy water problem may persist.