PKSolar 3.5W Solar Pond Oxygenator / Aerator with Battery Backup Premium PK Green 1-stone solar pond oxygenation kit with 3.5W panel and battery backup Water oxygen levels can drop at any time, especially when it's warm. Keep your fish and plants healthy with this pump Powerful 3.5W solar panel with built-in battery backup - your pond continues to be aerated even if it's cloudy Easy 2 minute setup. Maintenance-free brushless pump with 3m cable. Max flow rate &gt;2 Litres/min Can also charge battery or power pump with mains adaptor (included). A very useful feature in cloudy weather