advice please

[chbak014]

oh okay guys, hope you guys are having a very merry christmas. i know i am. anyways, here is my question, my tank is at a pH of 7.2 temp is at 78-79 degrees, and i think the water is at a hardness of 12. my question is that there is a film build up on my tank's walls and heater. my gf is watching the tank for me and she says that the water is cloudy and that there is build up. what could it be? i think it could be a bacteria boom, but, im not sure really. what can i do to "clear" up this problem? do i have to redo the whole tank? ie) re-gravel and re-cycle water? i don't think its left over food or anything cuz all my fish eat all of what is fed to them.
your help would be appreciated. thanks
-charley