Whitening white clothes- how to?

I use about 1/3 bottle of hydrogen peroxide with my detergent when washing a full load of whites. Bleach tends to make whites dingy and attacks the fibers. You can soak the whites in a 50/50 mix of hydrogen and hot water initially for about 30 minutes then throw in the wash.

I use to wash white school uniform shirts (polyester polos) in Resolve powder. I had been using Oxi-clean, and was amazed when I switched! The difference was night and day. I compared 2 shirts side-by-side, and the other one looked gray. I'm not sure if they have the powder in the U.S. yet

http://www.powerofresolve.ca/en/products/in-wash-powders/resolve-oxi-action-crystal-white-powder/

Remove stains from clothing, curtains, and tablecloths. Hydrogen peroxide can be used as a pre-treater for stains — just soak the stain for a little while in 3% hydrogen peroxide before tossing into the laundry. You can also add a cup of peroxide to a regular load of whites to boost brightness. It’s a green alternative to bleach, and works just as well.