From the start we decided to cover all the pens we built with hail netting. This is less expensive than bird netting with a smaller mesh but just as effective. Our first pen, as shown in the photo below, had a high roof as we were also caging laughing doves and other species apart from ducks in the enclosure.
The sequence of events should be; firstly decide on the size of pen and peg this out, then design and build your ponds. Be sure to get your levels correct as there has to be a water flow from the top pond, through any other ponds you create and then lastly into the Bio Filter which should be outside the pen. The last chamber of the Bio Filter will contain the pump.
Install all necessary piping from the pump to the entry point on the top pond. Ensure that pipes do not go under the ponds as if they have to be replaced you don’t want to dig under the pond! Be sure that the pipe diameter matches the delivery rate of the pump.
Once the pond structure is completed start building the actual pen. We used gum poles. (Ensure that these are suitably treated). The pole is set into a concrete foundation and braced with horizontal poles. All poles are bolted together, providing a strong structure.
Use wire mesh fencing on the first 1.5 meters of the sides and then attach the hail netting. This prevents predators such as cats etc. from breaking in. If budget allows build a foundation at least 50 centimetres deep and about 30 centimetres above ground level as this will assist in rat proofing the enclosure, it will also stop dogs from digging their way in. The wire then would start on top of the brick layer.
Entrance into the duck pen should be through a double door structure, especially if you have birds in the enclosure as this will prevent escapes, so you go in the first door, close it behind you then open the second door.