How to Replace Moldy Grout

Here's what you need to fix it: 1. Grout saw 2. Vacuum or soft brush 3. Abrasive cleaner 4. Rags 5. Grout (non-sanded for joints smaller than 1/8-inch, sanded for 1/8 or bigger) 6. Float 7. Citrus-based cleaner 8 Grout Sealer

Working in one 2-by-2-foot area at a time, run the saw up and down the grout line.

Vacuum out flaked residue, or use a soft brush to remove the grout pieces.

Put some abrasive cleaner on a wet rag and rub the joint to remove any remaining residue.