Welcome to the forum! I have two ponds each about the size of yours. My newest pond was built last December, filled this spring, and was very clear until about a month ago, when a plankton bloom started. If the turbidity is not mud, you might let it play out and see what happens. Are you feeding the catfish enough? If not, they may stir up the bottom foraging for food. Visibility of 24 inches is good.