OLYMPUS DIGITAL CAMERAA properly cared for birdbath will give you years of enjoyment.  First, be certain that the top is securely attached to the pedestal by either the locking system or if yours does not have one, use sticky floral tape or caulking tape to secure it.  Second, clean the bowl weekly and add fresh water every few days.  Clean with warm water, a mild detergent, and a stiff brush.  Rinse thoroughly before re-filling for the birds.  Clean water is essential to attracting birds and keeping them healthy.  Algae tends to form in shady areas more easily then in areas that get a 1/2 day of sun or more.  Winter storage – all birdbaths, including concrete, and glazed, should be cleaned, dried and stored either in the garage or home over the winter months.  Even if you use a birdbath heater there is the risk that you may crack the bath or pedestal due to electrical plugs coming unplugged, or a particularly severe winter like we just experienced causing snow and ice to pile up around the birdbath.  If you want to provide water for the birds during the winter, and believe me, they will appreciate it, then purchase a plastic birdbath, designed for this purpose, with an internal heater.  Enjoy the birds!