Sand bed maintenance in a nano?

[Koleswrath]

You're right on both points.
The OP should siphon as much detritus as possible from the sandbed so as not to rely on the sandbed sinking nutrients which is ultimately finite. (Disclaimer below)

In the case of someone who has not touched a sandbed in years it could be disasterous to go and start stirring things up nilly willy. However, it can be argued that eventually an undisturbed sandbed will cause more issues in the long run and that it would be a good idea to start slowly cleaning small sections at a time.