Biological FiltrationEcosystem PondsRecreation PondAdvanced Pond Filtration – Wetland Filters

July 10, 2024by Bill Seeds

What is a Wetland?

An Aquascape constructed wetland filter is an advanced filtration system that copies the natural wetland formula from nature with added technological advancements for ease of maintenance. Essentially it is a large pit in the ground with a snorkel and centipede at the base. This is the cleanout access which helps to disperse the water evenly. Then a layer of small aquablox increase dispersion and allows sediments to fall out to the bottom of the chamber. From there varying levels of gravel create the spaces for bacteria and aquatic meiofauna to filter the water from nitrogenous waste. You can learn about the nitrogen cycle here. The water then passes through the top layer of gravel where aquatic plants further filter the water, and then the water returns back into the pond, ideally through a waterfall to increase oxygenation.

The main reason you would want to install a wetland over a biofalls is the increased filtration capacity. These are designed for larger bodies of water or larger biological loads. They are also refuges for aquatic plants and can be incorporated into ponds as such.

Wetland Sizing

The general rule for wetlands is minimum 15% of surface area of the pond. 30% is the ideal goal for recreational ponds, but for even larger bodies a 15% coverage rate is sufficient. For exceptional water clarity you should shoot for a 50% ratio.

For example, if you have a 40 x 20 recreational pond, the surface area of the pond is going to be around 650 sf since you multiply the area by .8 in order to account for the fact the pond is not going to be a rectangle (unless it is designed as a rectangle). So that means you will need a minimum of 200 sq ft wetland in order to cover the 30% rule. This is why we have a 20 x 12 wetland on our Oasis package.

Wetland Pitfalls

There are diy alternatives to building wetlands but we prefer to stick to official aquascape guidelines for flow rates, gravel depth and size, and construction techniques.

It is imperative to understand the flow rates for your wetland otherwise your wetland will not work efficiently. Pump sizing, plumbing, gravel depth, gravel size, and dispersement are all factors that must be considered when constructing a wetland.

If you are interested in having me build your wetland or are considering a larger pond project fill out my contact form and we can get the ball rolling.


1103 Wildflower Drive, Merlin, Oregon, 97532
(503) 983-7663