Nolvasan is a disinfectant - so yes it would work. 15-20 minutes (or longer) would be fine. Also, be sure you clean it first (hot soapy water). Cleaning must be done before disinfecting for best results - there is a difference between cleaning and disinfecting. A lot of people don't realize it and unfortunately don't do both.
http://www.anapsid.org/cleaning.html
http://www.anapsid.org/maincleaning.html