Chomp Pro Algae Mildew Stain Cleaner and Remover spray. This Algae Mildew Stain Cleaner helps you maintain your deck's appearance by quickly and safely removing dirt, grime and stains caused by algae, mold, and mildew. Every outdoor surface requires maintenance and care. Your fence and deck are no exception. Chomp Pro's proprietary technology rejuvenates your deck without damaging bleach or acids, and when used as directed, is safe for your surroundings.