Pond Filter




Introduction: Pond Filter

About: 1979-1983 Chief Engineer On a 1927 117 foot motor yacht in the Pacific Northwest. 1984-2000 General Building Contractor, Sausalito CA. 2000-Present Principal IT Administrator , Comcast Silicon Valley Innovati…

I’ve been perfecting this design for 2 years. It works well on my 300 or so gallon fish pond containing 12 assorted fish. The filter media is based on a 2’ x 4’ sheet of 2” thick rock wool (also known as mineral wool) available from mcmaster.com, the housing is a milk crate, the top is a piece of plexiglass. Before we go further it’s possible that this mineral wool contains a small amount of formaldehyde as a binder. But I’ve gone through 4 media changes in the last 2 years and my fish seem happy.

Step 1:

Cut the rock wool to snugly line the milk crate inserting the bottom piece last. It’s important that the rock wool extends about an inch from the top of the crate to make a good seal for the top.

Step 2:

Line the inside with a piece of filter fabric ( I used a 4’ x 4’ piece) then trim the fabric to allow a 4 to 6” overhang. Then tuck the overhanging fabric between the rock wool and the crate.

Step 3:

Line the inside of the filter with wire mesh, to keep the cloth away from the pump. Again keep the wire mesh about an inch below the top.

Step 4:

Make the top, you need a piece of Plexiglas or other suitable plastic to cover the top,  use a hole saw to make a hole for the discharge line to pass through somewhere close to the center .  Rinse and soak the filter with a garden hose, insert your pump and sink it in your pond, wrap a piece of filter fabric around the discharge line and secure it with a nylon strap push it down to seal the hole in the Plexiglas. You’ll need to weight it down with a stone to keep the top on and stop the filter from trying to float away.

Be the First to Share


    • Stick It Challenge

      Stick It Challenge
    • Science Fair Challenge

      Science Fair Challenge
    • Electronics Contest

      Electronics Contest



    8 years ago on Introduction

    Extraordinary idea! Choosing stainless steel crimped wire mesh will give more effect in durability. http://www.brand4india.com/wire-mesh-suppliers/products/crimped-wire-mesh/


    Reply 8 years ago on Introduction

    Thank You, I would have used SS wire mesh, as it's a great material, except it's wildly expensive here in the US, compared to the cost of galvanized.