What Is a Gravity Pond Filter?

Asked By: Lawrence of Rochester, NY

A: Gravity-fed pond filter systems are low-maintenance, efficient solutions for mechanically and biologically filtering pond water. These units rely on gravity to pull dirty water through layers of filtration media inoculated with beneficial bacteria. Keep reading to learn more about how different types of gravity filters keep pond water clean.

How a Bottom-Drain Gravity-Fed Pond Filter Setup Works

Gravity pond filters sit outside the pond above the waterline and use pumps to transfer water into the tops of the units. Gravity then pulls the water down through multiple filter media chambers to remove visible debris and waste. The first chamber often features a pre-filter screen or netting to block larger debris from causing clogs. Subsequent filtration layers contain fine filter pads or sand and a thriving population of natural water-clarifying bacteria.

As water passes through the chambers, sediment and suspended particles get caught in the media and removed from the water. Nitrifying bacteria get to work breaking down microscopic waste, ammonia, and nitrates, converting these toxic substances into harmless gases and nitrites. Clean, clear water then returns to the pond from the bottom drain.

Gravity water filters process water at differing speeds depending on the types of media used, and faster filters are better suited for larger koi ponds and water gardens.

Is a Gravity Filter Right for Your Pond?

There are numerous options when choosing a koi pond filtration system, so it is easy to feel overwhelmed. We are here to help! Contact our koi pond experts online or by phone at 866-POND-HELP for tips and advice on choosing the right filter.