Planning is not necessary for a pond because they are considered an Outbuilding authorized development unless you live in a conservation or historic district. You may contact your local planning authority and explain your intended actions if you have any doubts.
In the UK, ponds are protected under various laws and regulations, such as the Wildlife and Countryside Act, which protects the habitats of certain species, including amphibians and fish, and the Water Resources Act, which regulates the abstraction and use of water from ponds and other sources.
There are no specific regulations for garden ponds in the UK, but they must comply with the general laws and regulations related to water use and environmental protection. Homeowners should also ensure that their ponds do not pose any safety risks to children or animals and do not cause any nuisance to neighbors. In addition, the Wildlife and Countryside Act of 1981 (WCA 1981) makes it illegal to knowingly kill, damage, or remove an animal from its pond. The same rule applies to any building or other structure that an animal uses as a haven.
To clean a pond quickly, remove any large debris using a net or skimmer and drain the water. Use a pond vacuum or a pressure washer to remove stubborn debris and algae. Refill the pond with fresh water and add beneficial bacteria to restore the balance of the ecosystem.