Let your fish do the hard work

The pond pump pre-filter you don’t clean.
Your fish do.

Learn moreSee it in action

The GrazenFilter® is a patented pond pump pre-filter that takes advantage of fish's instinctive food-seeking behavior. Fish keep the GrazenFilter® clean, so pond owners don’t have to. 

Read more

Unlike other pre-filters with their fortresses of cages, sponges, and media buckets, the GrazenFilter™ protects pond pumps with thin, extremely durable, stainless steel screens. The pond pump pulls and lightly holds pump-clogging debris against the screens. 

What's pond debris to you is a feast for a fish. Convenient. Plentiful. Nutritious — Like a healthy fast food restaurant for fish.

Read more

Every bite the fish take, and they take a lot, restores free-flowing surface area. They chew and swallow what they like, spit out what they don't. These leftover, smaller bits pass freely through the GrazenFilter™ screens and your pump, then onto other biological cleaning systems downstream.

For those infrequent times when the fish fall behind in their cleaning duties, a supplemental backwash system can be engaged to open free-flowing surface area and move debris away from the GrazenFilter™. The backwash also serves as a convenient way to add water to the pond.


Fish naturally graze along the GrazenFilter®, opening small bits of the surface with every nibble. They peck away all day long, maintaining ample clear surface area to keep your pump intake flowing at 100% capacity.

Resilient, purpose-built design

The GrazenFilter® is built to survive long-term submersion in harsh aquatic environments. Corrosion-resistant components are made from stainless steel, brass, and safe, submersible plastics.

The upper screen’s elliptical shape promotes larger debris shedding. The flat, lower screen, raised off the pond floor, dramatically increases surface area while giving fish full access.

Backwash backup

If it’s too cold or there’s simply too much debris for the fish to handle, a backwash system opens free-flowing space on the filter surface and underneath the GrazenFilter®. It doesn’t take much, just a blast of water from the internal jets to loosen and open gaps in the screen and push away debris.

The backwash system doubles as a convenient way to add water to the pond. Plus, occasional backwashing really stirs things up for the fish. When the backwash dinner bell starts clanging, the fish come running.

Multiple Configurations

The GrazenFilter® concept is applicable over a wide range of situations. Pumps can be mounted inside the filter cage. Or, they can be connected outside of the pre-filter. Filtering surface area can be sized to the flow rate appropriate for most any pump and pond.

How It Works

Water flows through the GrazenFilter®

Like other pre-filters, the GrazenFilter® is placed ahead of your pump letting water flow through while preventing occlusive debris from getting through to the pump’s spinning parts. Unlike other pre-filters, you don’t clean the GrazenFilter®. Your fish do.

Debris collects on the screen

The GrazenFilter® is a food magnet. As the pump pulls in water, all the stuff we humans consider debris, collects lightly on the GrazenFilter’s® thin stainless steel mesh.

Always on the prowl for a tasty snack, fish find such an easy meal irresistible. The GrazenFilter® is a well-stocked dining table laid out like a Sunday pot-luck dinner. 

Every nibble restores water flow

With every nibble on the GrazenFilter® dinner table, the fish restore free-flowing surface area. They pull off big bites, grinding them down to find the nutritious parts within. They swallow what they like, then they spit out the rest, like we spit out watermelon seeds. These masticated, smaller bits drift through the screen and unimpeded through the pump, eventually making their way to downstream biological or mechanical cleaning systems.


We are looking for licensing partners and field testers. Enter your information to get more details.

For field testers, please provide as many details about your pond setup as possible – size, pump location, pump specifications, etc.. The more information the better.

Got it! We'll be in touch!
Oops! Something went wrong while submitting the form.