Regular maintenance is very important for a successful pond. The workload isn’t heavy but you need to take weekly action between April and October. Look carefully to identify problems before they become critical. But with a little maintenance, a correctly positioned and planted pond can be a pleasure, not a chore.
Keeping the pond clean
Dead and dying plant material rots, polluting the water, so use a fine mesh net to clean out the pond each week from spring to autumn.
Don’t feed any fish unless the water temperature exceeds 10°C (50°F). You will notice when they are active and searching for food – over winter they live on fat reserves and plant roots. Feed them sparingly at first so that any uneaten rotting food will not pollute the water.
Maintain about 60% surface cover by planting water lilies. It helps to keep the water temperature low and restrict algae growth. There will still be an annual spring flush of green water when temperatures warm up, but your pond should clear when the lilies start to grow.
In autumn, when marginal plants die back around the edge of the pond, cut off the surplus foliage before it drops into the water.
Clean out your filter and pumps (if fitted) in autumn and at other times in accordance with the manufacturer’s instructions.
Tip: Leave the net in place over winter if herons are a problem.
Keeping the pond in balance
Keep an eye on the pond in warm weather and replace evaporation losses regularly, but gradually, to prevent a sudden influx of fresh water.
When you see fish coming to the surface to breath at any time of the year, it indicates that the water oxygen is low. Turn on a fountain, if you have one, to oxygenate the water. If not, sprinkle the surface with fresh water from a hosepipe.
A gaseous exchange between the pond and atmosphere is necessary to keep up oxygen levels and allow carbon dioxide and other poisonous gasses to escape, so if the surface freezes in winter it is essential to keep an area ice-free or the poisonous gasses will build up and kill your fish and plants.
Turn your fountain off in cold weather. The mixing of warmer water at the bottom of the pond with cold water at the surface will lower the overall temperature and harm your fish. Only use fountains in cold weather if they can be lifted to the surface level so that mixing will not occur.
Tip: Don’t break winter ice by hitting with a hammer – the shock waves can kill your fish. Instead, place a hot saucepan near the edge of the pool and gradually melt a section of ice.