Hi, I have well established (11 years), 29 gallon, freshwater aquarium. I have 9 fish, including an angel that is about 6 years old. In the last couple of weeks, I started noticing that the water looked milky. I did a water partial water change & cleaned the filter (The power filter is a Marineland/Biowheel. I did not, of course, clean the biowheel). The next day it still was cloudy & also had lots of bubbles at the top, almost soapy looking. I tried to think about what I may have done different lately. I did add live, aquarium plants to the tank back in Nov., but plants have been doing well & the tank looked just fine, until recently. We live in Florida & had some freezing weather earlier this month. I did adjust the heater in the tank a few times to keep it at around 78 degrees. We do not have a heater with set temps, so I had to keep adjusting it. So over a couple of days, the tank went from 78 to about 74, up to 80 & back to 78. I read somewhere that a temp. change could cause cloudy, bubbly water? The fish seem to be doing fine. My angel isn't eating as much, but I don't think he likes all the bubbles on top (he's very skittish). When I did the last water change (the water was milky, but no bubbles) I did place some plant food tablets in the gravel around the plants. Could this have caused the bubbly water? I checked the ammonia & Ph. Ammonia level was 0.25 ppm. Ph was 6, but I have had issues with Ph in the past. I just add a handful of natural coral sand to the gravel & this usually helps. I have never seen cloudy, bubbly water in my tank before. I am at a loss. Anyone know what could be causing this & what can I do to fix it?