to clean the bladder, (camelback's, not yours) fill it with water and drop a couple of your nanna's denture cleaning tablets in. leave it over night, drain and rinse. it even gives the tube a clean if you let it run out that way.

during summer, i leave a little bit of water in the bladder and lay it flat in the freezer. this keeps the bladder fresh, and when you fill it up, it keeps the water (and your back) cool during your ride.