I'm with rk911. Pretty much the same with me.
Aside from that, many RVers totally over chlorinate their tanks. Here's what a professional chemist who worked at city water treatment plants his entire career says about your fresh water system:
Troubled System (smells, floating stuff): 0.13 * Tank size = oz of bleach to add to the tank (Ex: 7.8 oz/60 gal)
Preventative Maintenance: 1 oz bleach / 60 gallons.
Remove average smells: 1 & 1/2 cup vinegar / 60 gallons.
Sweeten water: 1/2 cup baking soda / 60 gallons.