Is your tank cloudy green (algae) or cloudy whitish (bacteria). the algae blooms I've had clear with a micron filter in a 350 or HOT Magnum but if it's a bacterial bloom these microns may not work. Make sure your filters are not dirty as this can harbor large quantities of bacteria. Also what is your fish load, feeding habits, etc. High fish load with overfeeding is a prescription for cludy water. Eric