Oxygen Bleach Grout

What stores sell the most focused of this kind of thing.

I need to clean my grout and do not want good cleanser Ajax, but a real 80 percent or more concentrated.
Oxi-Boost is gone, even though it ranks high, the other brands?

Here is a place where you can buy 80% oxygen cleaner (this is called "Just renew" www.refreshyourhome.com

If you go to Menard / Lowes they can tell you what to use the glue that is recommended and it will be clean. You must visit the service that sells tile and grout. I've never been able to find something that will clean the grout clean with the exception of bleach and brush straight.