The LG - 4.5 Cu. Ft. 8-Cycle Ultra-Large Capacity High-Efficiency Top-Loading Washer, Model # WT1201CW has a "Tub Clean" feature on it that you use to clean the tub. LG recommends that you clean the washer tub on a regular monthly basis to keep it clean for hygienic use and prevent the build up of black mold and germs in the air in the tub that might affect your health. You can also add lime scale remover into the detergent dispenser draw. If a mildew or musty smell already exists, you should run Tub Clean for 3 weeks consecutively and never load your laundry while you're using this mode!
There are more helpful suggestions under the maintenance section in your manual on page 28 if you would like to read those....IFV