The purpose of a pond filter is to keep the water healthy and clear by removing debris such as leaves. You might wonder how to support a natural aquatic ecosystem. The answer is by mimicking Mother Nature! By doing so, we can create beautiful and properly functioning filters for ponds. Sounds simple? It really is.

What is a Constructed Wetland Filter? (also called Bog Filtration)

A constructed wetland filter is a large biological filter for your pond. It decomposes pond wastes to convert them into more sustainable compounds. Constructed implies manmade; wetland describes a vast aquatic ecosystem that filters water in order to sustain aquatic life and even life outside the aquatic ecosystem.

Simply put, a wetland filter breaks down nitrogenous waste such as leaf and plant debris, fish waste and anything else that might affect the ecosystem. The biological term for this is the nitrogen cycle. There are three main elements to this cycle – ammonia, nitrite, and nitrates.

 This cycle is repeated again and again, keeping your aquatic ecosystem stable. Simply, ammonia in any amount is not safe for your fish and the end result of the cycle conversion is nitrate, plant food. A properly sized and functioning biological pond filter will help maintain safe ammonia levels in your pond, keeping your finned friends healthy and happy. A clean pond provides good clean water for the wildlife including beneficial insects and birds outside the pond.

How and Why Does a Constructed Wetland Work So Well?

 A constructed wetland provides more surface area than a traditional filter for beneficial bacteria to colonize.

Another benefit is increased water volume to the pond system. Remember biological filtration is just one part of the three-part recipe that includes a pumping system and a mechanical filter (skimmer). Water is moved through the system by the pump, which draws water through the mechanical filter and pushes the skimmed water through specialized equipment located at the bottom of the constructed wetland. The water then flows through a settling chamber, into a gravel substrate that provides a massive amount of surface area for beneficial bacteria and aquatic plant roots before reentering the pond.

What Does a Constructed Wetland Filter Look Like?

It is the most naturalistic looking filter available for ponds. This filter provides area for your aquatic plants to thrive. Many varieties of aquatic plants may be used and are most often called marginals. Marginals are found in nature in the shallow edges of a body of water or in wetland areas.

A constructed wetland filter can be used for small ponds, large ponds, and small lakes. When choosing a filter, consider the size of your pond and shape of the area. If you have questions about pond filtration, give Sweetwater Landscape a call at (707) 887-0140 or email us at