A Guide to Modern Koi Pond Construction

There are now many different vortex chambers being made that it is very difficult to know which to chose from.
It is always a good idea to see one in operation on a completed pond before agreeing to purchase one as they do vary quite considerably in how well they operate. Take advice from your supplier.
Below are a few things to look at when deciding which one to purchase.

This rough sketch shows the inlet for the 4 inch (110mm) pipe from the bottom drain, and this is generally considered to be the best position just above the cone and entering at a tangent. It allows for an easy flow of the water around the inner circumference.
There are a few manufacturers who have the entries on the side with a 135 degree bend on the end of the pipe or pipes. In this example there are two entry pipes, and it will be noted that the vortex chamber is not full as it is not yet in service.

It is quite common to have two inlet pipes if there are two bottom drains feeding one vortex chamber, and this should be situated at the same height as the first one, and facing in the same direction. This is preferable to joining the two pipes before entering the vortex chamber.

It is generally considered that the best position for the outlet pipe to the first filter is in the centre of the vortex chamber as shown here.

There are a few koi-keepers, and one dealer in particular, who say that the outlet should be taken from the side.

Another important parameter h is the height of the vortex chamber in relation to the diameter. In many cases it has been found that shallow chambers are not very efficient.
As a general figure the height for a 36 or 40 inch diameter chamber should be at least 50 inches.
The height of the chamber will also effect the dimension d which should be as long as possible to give the solids more time to settle out before the water exits the chamber.