I've used timers for lots of different stuff - and the most reliable I've found are the simple analogue timers where you push in an outer ring of pegs for the hours that you want the power to flow (in other words, on). Even more amazing, they are specifically for Aquarium lights - but they work for anything really well.
Like this one:
http://www.amazon.com/Marineland-Light-Timer-Hour-Grounded/dp/B001F97756
Like this one:
http://www.amazon.com/Marineland-Light-Timer-Hour-Grounded/dp/B001F97756