I thought I'd share this with others since it has been a big help to me. I've had trouble in the past keeping hinges and screws from rusting in the canopy of a tank. I started taking a qtip and lightly swaping on some medicinal Petroleium Jelly(pure and unscented) on these and have had no rust problems for several years now. One application usually lasts a year or more.
If you already have rusty parts I recommend replacing them then doing an application of the jelly to protect the new hardware.