Pressurised Pond Filters: A pressurised filter is a sealed, water-tight canister that uses the pump’s flow rate to push water through a series of sponges, which filter out debris and waste from the pond. Key features include:

• Installation Flexibility: Pressurised filters can be installed either above or below the pond water level, providing flexibility in placement. This makes them ideal for ponds with limited space or where burying the filter underground is desired.
• Water Flow: These filters use pressure to pump water against gravity, which is advantageous for creating features like waterfalls or fountains.
• Ideal For: Open-space ponds with minimal surrounding foliage, as they can be buried underground up to the securing strap.

Box Filters: A box filter or gravity pond filter relies on gravity for water filtration. It works by allowing water to flow naturally through the filter and return to the pond via gravity. Here’s what you need to know:

• Gravity-Based Operation: The filter should be installed at the same level or slightly above the pond surface for gravity to pull the water back to the pond. If installed too low, the water will not flow properly, and the system could flood.
• Waterfalls: To use a gravity filter with a waterfall, the filter needs to be positioned at the top of the waterfall, and a suitable pump must be used to push water uphill.
• Ideal For: Ponds with a gravity-fed system where water is naturally returned from the filter to the pond.

Summary:

• Pressurised filters are versatile, work well with waterfalls, and can be buried underground. They push water through the filter using pressure.
• Box filters rely on gravity, are installed level with or above the water, and require a pump with sufficient head pressure to return water to the pond or waterfall.

Choosing the right filter for your pond depends on the setup and the features you wish to incorporate.