Best Way to clean your tub. Period. Make a paste of Borax for that grimy tub and tile or try swimming pool tile cleaner. For soap scum and water spots on glass doors, use equal parts of hot vinegar and Dawn dish soap in spray bottle. Just spray it on, scrub, rinse and be amazed. Allow it to sit overnight for stubborn stains and scrub with a dryer sheet or magic eraser.
Add orange peels (or any citrus peel) to a quart of white vinegar in a closed container and let it set for two weeks. Combine citrus/vinegar solution half/half with water and use for cleaning. Works on floors, tile, fixtures, etc. Smells good and is tough on scum! Best of all there are no chemicals.