Background

Setting up a pond is an especially tricky and expensive business. Quite often you don't know enough and you get one person's point of of view which conflicts with another's. But pond people the world over are united in the fact living creatures like oxygen.

So how do you give all your aquatic chums the air that they need ? Spend lots of money and time ? NO ! You make a pond aerator with bits lying around the garage.

Think it sounds too easy then we'll give it complicated name based on the principal it uses a 'Venturi'.

Construction

First of all here's an overview picture.

Generally most pond systems have a overflow of water mine is due to capacity of the pump being greater than that of the filter I used to return it to the system in a very boring way until now.

All you do is cut into the water overflow insert a 'T' piece' and take the perpendicular exit (the one at 90 ° to the other) to the surface via a pipe. This becomes the intake. With a 3/4" system I found a piece of 1/2" garden hose fitted snugly inside the 'T' piece. The bottom of the intake must be cut at an angle see picture below.

A restrictor (I used dowell) is inserted into the top of the intake to cut down on the noise.

That's it here's a cutaway to help you.

If this fails to work then adjust the height of the aerator w.r.t the pond water level

Technical

This works on the 'Venturi' principle same as a carburettor I'm told. The water flowing through the 'T' piece splits and goes around the angled intake and rejoins on the other side. Behind the rejoining a vacuum is created and the only thing that can be found to fill it is air drawn in from the restrictor.

If Even This Bores You

If you turn the intake 180 ° such that the angle faces the flow you get wet.

Update

1 year on and all is fine. The Venturi nozzle had become clogged (with a leaf ?) so I now keep a screwdriver handy to poke such obstructions out - a quick task and infrequent. Having cleaned out the pond filter and removed some debris from the pump impeller all is gushing and bubbling to a fine °.

Hope you try this project on any scale.