It is advised that garden ponds be at least 2 feet deep to ensure sufficient water volume to avoid this issue. If you reside in a frigid climate where the pond may freeze, you should dig the pond three feet deeper. The average depth of koi ponds should be three feet because the fish require additional space to swim and develop.
This depends greatly on the reservoir. If the pond is modest and decorative, it may only require cleaning once a year. If the pond is larger and used for fishing or swimming, it must be cleansed more frequently, perhaps every two to four weeks.
It is not recommended to sanitise them more than once per year, and once every three to five years is preferable. You will need to clean the pond less frequently if you keep it clean throughout the year by using nets to prevent leaf accumulation and removing plant detritus as it begins to wilt.
At least half of the total volume of water in water gardens (ponds with plants and koi) should be circulated every hour. This means that for a pond with a capacity of 2,000 gallons, you should pump AT LEAST 1,000 gallons per hour (GPH).