A Guide to Modern Koi Pond Construction

Purging the drains

When vortex chambers were first used there was quite a problem with some of the horizontal pipes becoming blocked and the flow of water being seriously restricted. Because these pipes are so far below the surface there is no way to allow for access to rod them out as is normally the case with main drains. If you talk to koi dealers who were in business then they all have horrifying stories to tell, including in one or two cases digging up the pond base.
To overcome this problem it is necessary to ensure that the pipes underground are as straight as possible with the minimum of bends. As mentioned on the previous page ensure each pipe has a shut off valve.
Another precaution that should be taken at regular intervals, some members consider this to be once a week, is to carry out the procedure of purging the bottom drain pipework as laid out below.


[Vortex chamber]

The diagram on the right shows a pond system using a vortex chamber. Valve A is a 4 inch valve in the main pipeline from the pond bottom drain to the vortex chamber, and is normally open.
Valve B is usually a two inch valve, although it could be a different size, or a stand pipe. This valve is normally shut.

 
[Vortex chamber] Step 1. Close valve A so that the flow of water to the Vortex chamber stops.Open valve B so that the vortex chamber is completely empty.
[Vortex chamber] Step 2.Valve B remains open. Open valve A fully so that there is a full flow of water through the pipe from the bottom drain, and this should clear any sludge lying in the pipe. When the level of the water in the vortex chamber reaches the bottom of the pipe from the bottom drain then shut valve A. If the water is still dirty then carry out this step again.
[Vortex chamber] Step 3. When you are satisfied that the pipes are clear then shut valve B. You can then open valve A. The vortex chamber will fill up, and the flow to the filter system will begin again and the system will be operational.
NOTE. These diagrams show only one bottom drain, but if you have more than one fitted then carry this out for each one.


We can now look at an alternative way to do this using a bypass.

 
This page updated January 2006
This website started with a booklet which I made up originally for the help of those members of the BKKS - South Wales Section who were intending to start building a koi pond, and as the website has expanded more information and articles from other people have been included. This is for general guidance only, and we do not take any responsibility for problems that might occur by following these ideas. It is important that you check out everything in your area, and check on local laws and rules that may apply.
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