I had seen a Pinterest post where someone cleaned their grout using carpet cleaner and I wanted to give it a try. My mom had also recommended this stuff called Zep which she said worked well on her tile; I wanted to try it too. Which one to choose??? I decided to perform a scientific experiment and test both! Here are the results.
During: As you can see the carpet cleaner foams up quite well, where as the zep only foamed in little sections.
After: I rinsed both sides with a wet rag.
Conclusion: Zep cleaned the grout more evenly, but left it still dark in color. Carpet cleaner made it lighter in color, but it was spotty (there were still some dark spots).
My decision was to continue using both: 1st I applied the carpet cleaner to get the grout lighter 2nd I applied the Zep to even it all out. The end results were good! Although, I would like it to still be a little bit lighter since I can see the grout in places where the previous homeowners had a rug and the grout is A LOT lighter in color...