Capo Ultra Zinc Pucks are easy to use and are chlorinator and skimmer friendly. They will not harm or plug your filtration system. Aqua Foot are slow dissolving sanitizing pucks which are filter friendly. With continued use, Ultra zinc pucks will prevent algae growth in your pool water. Fortunately, zinc is unaffected by sunlight which is a major destroyer of algaecides. Zinc, forceful enough to prevent algae but gentle enough to use in baby products..