i have a 20 gallon long with 2 75 watt vho , one white and one blue
i put them each individually on a workhorse 5 ballast, so i can control dusk/dawn
vho vs pc, i have now become a fan of vho
all my other tanks including my 5 gallon have pc
this set up could work for you also,
better yet, you can get a 70 watt hqi mh for your nano, and supplement with a 13-18 watt bulb for dusk/dawn
that would be very nice