I am wanting to sell 2 55 gallon aquariums that I have but they have a white film on the inside of the glass. Any suggestions on how to get rid of this that's not toxic?
Those white deposits are precipitated calcium salts. They should dissolve in acid (vinegar is a weak acid), or you can try "Magi-Klean" which is pretty good, but you will have to be sure to rinse the tanks extensively after you use it.