Dont think theres harm in turning it off because i turn mine off at night, well i used to till we moved. Now tanks in the lounge so i dnt hear it lol.
But you could try to find a quieter one?
Oh and make sure u have a fair bit of surface movement, put ur filter outlet closer to the top so it moves the surface around. Will help with oxygen while the air pump is off.
Regards,
Indir