We use OASE Biological filter systems on our swimponds. This is because they offer a reliable way of cleaning the water. They have drums, sieves or both inside them that remove physical particles from the water so its clear. They also have a biological compartment which is filled with bio media. Bio-logical filter media houses nitrifying bacteria that turn ammonia in the dirty water into nitrite, then the less deadly nitrate. This nitrate is then release back into the pond and is used by the plants. Along with the UV clarifier this creates a safe outdoor swim in the UK.
What’s also great with OASE filters is they self clean meaning that maintenance is actually very minimal on the whole system.
These can be installed with a bottom drained or pump fed set up. If you’d like more information on these filters and why they are the best for swimponds please get in touch.