Why is my water cloudy in my freshwater aquarium?

I have a 29 gallon freshwater aquarium that has been active for about 9 months. Our water has gotten very cloudy (like white cloudy). I took my water in to the local pet store and everything checked out fine except my pH was too high (7.6), we figured out that our city water was responsible for the high pH. We have gotten the pH down by doing water changes with distilled water. The pH is now right about 7.0. We have 3 black skirt tetras, 3 serpae tetras, one ram, and one clown loach. Until about 2 days ago we had a pleco. It has since died. Our temperature is always about 76 degrees. We got the cloudiness cleared up for a while (about 2 weeks) but then it got cloudy again. We haven't added any new plants, decorations of fish to our tank. We have done water changes weekly. We tried Clarity water clarifier and that seemed to make it worse. Any ideas on what is causing the cloudy water?