What color is the water? Is it like a tea color? If it is, the driftwood would be to blame. Driftwood should be soaked in water for up to 3 weeks, changing the water it is being soaked in ever couple days.
When you clean the filter, are you doing a major cleaning? Your tank can get cloudy during the cycling process due to the bacteria bloom. If you do a major cleaning of the filter, you kill all the bacteria and have to start the cycle process almost from the beginning.