Inspect your pond edges and take a close look at the water level. Make sure the pond is staying as full as it should. If you’ve turned off your stream or waterfall for the winter, turn it on and check that everything is working fine. A rock might have fallen out of place, or the soil might have settled in along a bog edge. Clean up all fallen leaves in and around the pond. Use a vacuum to remove any organic debris on the bottom. Its easier to just drain the pond and clean it if there is more than half-inch of bottom sludge. You’ll have to set up a holding tank for your fish, but its worth the extra effort. That muck in the pond bottom can harbor and grow many different kinds of organisms that can harm the fish and pollute the water. These organisms respond to warming temperatures very quickly and can easily cause diseases and illness in your fish in the spring. The organic matter at the bottom of the pond also acts like a fertilizer to feed algae blooms once the weather and the water starts to warm. Save yourself a lot of agony and headaches later – clean the sludge out of the pond now, before it
has a chance to work its summer mischief.
2. Check your Pump and Filter System
Take out your pump and make sure that it’s clean and that it’s working properly. Look for any cracks in the housing. Make sure the impellers run freely, without being blocked by dead snails or debris. Check your filtration system and clean your filter media. If the filter material looks worn or dirty, or if it doesn’t clean up well, then replace it with new media. Add new beneficial bacteria to your pond. It may not do much when the water temperature is below 50º F. Just the same, it will be there ready to go into action as soon as the water warms. It’s especially important to seed your filters with beneficial bacteria early in the spring because algae begins to grow as soon as the water temperature in the pond rises. Don’t wait until your water is green with algae—it will be too hard for your bacteria to catch up.
3. Check the Water Quality
Use a reliable test kit to check your water quality for ammonia, nitrite and nitrate. If your readings are not in the proper range, you’ll know about it right away and can take the necessary steps now, before your system is completely overwhelmed. 4. Check the Fish
Spring is a very stressful time of year for our pond fish. The water temperatures fluctuate considerably from day to night and from one day to another. The fishes’ immune systems may not be up to the task. They have gone for several weeks or months without much food. Check them for any external signs of disease or injury. If they are not healthy, treat them and consider moving them to a quarantine tank until they have recovered. Some pond keepers add a small amount of salt to the pond or do a salt dip to give the fish a jump start toward summer. It’s best to wait until the water temperature is consistently above 50º F or 55º F for a few days before you begin to feed the fish. Feed them low protein food, and don’t over-feed them. They will enjoy natural foods, too, such as peas, lettuce, or even duckweed. Make sure the food is high in Vitamin C and other nutrients. The fish especially need very nutritious food this time of year. 5. Check the Plants Water plants that have overwintered in the pond are starting to wake up for spring. Remove dead leaves from the plants, since the spent foliage will simply decay in the water and become fodder for an algae bloom as well as harboring pests and diseases. If you moved your lilies, lotus or marginals to the deepest part of the pond to hibernate during the winter, move them up now so that they are closer to the water surface. The spring sun will warm the upper layers of the water first, and the lilies and lotus will start to sprout and grow. This is especially important for plants that don’t like to be submerged, such as water forget-me-not and parrot feather. Some plants are
best transplanted very early in the spring. Iris are often transplanted before 
they have put out much growth, so that they won’t be disturbed as they set flower and bloom. So, too, with lotus, which are best transplanted before they have started to sprout and grow. Most plants, though, can wait to be moved to bigger pots once it’s warmer outside. Hardy water lilies and most marginal water plants may be transplanted when they are actively growing. Spring is the time of year to fertilize plants that are growing early, such as marsh marigold and sweet flag. Wait until the water reaches 65º F before fertilizing water