Why are there suds in my dishwasher tub?

You may have used incorrect detergent. Use only automatic dishwasher detergents like Cascade® Automatic Dishwashing Detergent to avoid sudsing. To remove existing suds, open the dishwasher and let them evaporate, then add 1 gallon of cold water, close and latch the dishwasher, and pump out water by slowly turning the dial until a drain period is reached.