Here the bottom drain and airline runs can be seen. The whole base is laid on a waterproof membrane to reduce the amount of ground water mixing with the concrete when poured.
This picture shows the pipework run as it exits the pond. The wood plank is approximately where the pond wall will sit. The drains go vertical for around 18" at this point as do the airline feed pipes. Another set of 90deg bends then direct all the drain pipework to the filter house at a depth of approximately 5ft. A pump that keeps the excavation dry is also located at this point.
The airline tubes have now been fitted and these 1" pipes will follow the drain runs back to the filter house where they meet up with an air pump to power the diffuser domes that will be fitted at a later date.
Radius Bends made from pressure pipe have been used in this construction. Note how the bend is radiused to allow maximum water flow through the drain.
Due to a high water table a sump type pump has been installed below the level of the pond base. This is to ensure that the excavation does not fill with water during the construction. The pump is contained in a mesh bucket filled with gravel. The photo also shows the bottom drain pipework and airline returns.
