The fitting of Vortex chambers has recently become very popular in the United Kingdom, and most of the members in our club seem to fit them when they are building a new pond.

There has been quite a lot written about vortex chambers, and I have seen several comments which said they cannot work because it requires very high revolutions for sufficient centrifugal force to be generated. This is true if you are comparing it with an industrial centrifuge, but even at the speed at which the water goes around the chamber it is sufficient for the heavier solids to drop to the bottom and remain there until they are drained away. Other hydrodynamic forces come into play here also. The amount of solids removed in this way proves that it is working. Smaller floating debris like algae is unlikely to be removed efficiently, and will still be carried over into the first biological filter chamber.
The efficiency of the unit does depend a lot on it's design, especially the diameter, height, and especially the positioning of the inlet and outlet pipes. The pumping rate can also be very important.
If you have any doubts about the efficiency of a vortex chamber then do try to visit a pond keeper that has one in use as I am sure you will be quite impressed with it.
Careful thought must be given to the correct size of your vortex chamber(s) when designing your koi pond, taking into account the necessary pump rate.

Installing a Vortex Chamber.

The installation shown below in fig.X is very similar to that shown in fig.2, but this time the Vortex chamber is situated between the bottom drain and the filter system, and in fact now becomes the settling chamber.
It will be noted that there is a gate valve situated between the bottom drain and the inlet to the vortex chamber, and this is very important so that the pipes can be flushed out. This sketch shows only one bottom drain connected to the vortex chamber, but usually there are two or three, each connected with their own pipe and valve.

Some of the chambers have the external pipe fitted directly on the side without any internal pipe. To get the best results there should be an internal pipe of the same diameter, and this pipe is positioned as shown in fig.X so that the water is drawn from the centre.

TIP. In the drawings above the stand pipes in the discharge chamber can be lifted to release the water to the main drain. This way was very popular until the mid eighties but now that slide valves and ball valves have come down in price then most koi keepers prefer to use them instead.

When someone is beginning to excavate their pond they often ask what size to allow for the vortex chamber. These vary considerably in size. Even when you have decided to have a 36 ins or 48 ins diameter unit the heights do vary from one manufacturer to the other. They can be from 36 ins high up to 84 ins. For this reason it is essential to purchase this item before you start digging so that then you can dig out the area where the chamber is to be fitted to the correct depth.

Quite a few of these vortex chambers are free standing, but some of them have to be buried in the soil. The free standing type should be stood on a six inch thick concrete base.

In the case of connection to a Vortex then it will be necessary to use more than one elbow to connect up with the inlet, but it is still necessary to make the flow as smooth as possible.

The two sketches above show the sizes of the most popular type of vortex chamber used by our club members. The inlet pipes are usually 110mm for the use of terrain pipe, but you can specify 4 ins diameter if you are using pressure pipe.
The outlet pipes are usually the same size, but you must bear in mind that the maximum amount you can pump through this size pipe is just over 2,400 gallons, so if you are intending to use a larger pumping rate then you should specify a 6 ins oulet.