Whats the best way to clean light colored grout between floor tiles?

http://www.hometalk.com/categories/cleaning/household/grout

A scrub brush & elbow grease.

Scrub it then re-color it with a product you can find at Lowes or H.D., or, or. Dirty grout is difficult to clean but you can clean the grout, let dry, then use the colorant. You can buy a plastic bottle with brush (I found mine at H.D.). You fill the bottle and squeeze product out to paint the grout. After painting use a sealant -- I used at least two coats of sealant. On my (kitchen) floor I used a water-based varnish, letting it dry between coats. All I had to do to keep it clean was mop the floor.

Buy a grout brush and Zep Commercial Grout Cleaner. You can get a pretty good brush on Amazon. If it's severe, use a drill and modify with a brush. Once you get clean, make sure you seal the grout (even if you paint it).

Clorox toilet bowl cleaner with bleach, leave it on awhile then wipe

Absolutely the very best is hydrogen peroxide. pour a little on the grout line then brush. It works great.

Hi Jeannie, You can make a thin paste of hydrogen peroxide and baking soda. Apply it to the grout and let it sit for about 10-15 minutes. Scrub with an old toothbrush and rinse clean. If the grout between the tiles has worn down too far, it may be a better idea to first re-grout and then seal. You can also buy grout pens to quickly “recolor” your grout and make them look new again.