Algae build up can become a problem in water gardens. Barley straw or pellets placed in a pond or stream in spring prevents algae growth. A good filter or clarifier also prevents development of algae. Use a fountain or waterfall to keep the water aerated and ward-off foul-smelling bacteria.
Watering aquatic plants couldn't be easier. Simply maintain the pond level at the correct depth so plants at the water's edge don't dry out and so that roots of submerged plants remain covered. Refill your water feature before the water level drops several inches. Automate the process by installing a float valve that automatically turns on the water when the level drops to a set point and shuts off when full.
Floating plants derive their nutrition directly from the water. Water lilies and other containerized plants, however, often need fertilization to grow and bloom well. Several types of commercial water garden fertilizer pellets are available. Place these directly into the potting soil of container plants.