Are you sure the tank smell is the tank and not some water that has been slopped on carpet during a water change and not fully dried, and the spilt water is causing a mouldy/ rotting smell? Just a thaught, otherwise I would be checking that no plants have rotted in the tank.
As for air fresheners while your at home you can burn candles (almost any scented ones will be fine but just don't burn them too close to the tank, just in case), you could also burn incense as has been suggested, even simmering oils that are easy to get from "alternative" type shops would be ok. You could also put out some tubs of pot pouri that requires no flames or electricity, and just needs you to stir it occasionally and refresh it when needed. Baking powder will absorb smells as will carpet powders that are designed to be sprinkled on carpets and later vacumed up.
But all of these will only mask the problem and you really will need to find the source of the smell and eliminate it for the future.