Definately leave the air on. Put the light on a timer, they cost like $5. A good idea regardless that you are leaving. And if you turn your powerhead on at a certain time, just put in on timer as well or you can just not worry about it. That isn't that crucial. Feed them before you leave and maybe put in a couple feeders if you're really worried about it, but 2-3 days isn't a big deal.