There have been many e-mails received regarding the fitting of pipes for the venturi etc to a liner pond.
The main part of this website deals with the building of concrete ponds, but as far as the items which are attached to this type of pond the same applies to a liner pond and most koi dealers can supply the fittings for either type.

This photo shows a 1.5 inch fitting suitable for a straight pipe that would be used say for a venturi. This is as you would buy it from a dealer.
These fittings are also available in most other sizes such 2ins, 3ins, & 4ins.

In this photo the parts are laid out ready to be used. The main part is fitted to the pipe and put in position behind the liner. The holes for the screws should be located and small holes made in the liner.
The flat plate is then fitted from inside the pond and the screws put into place and tightened up.
The liner is then cut out from the centre of the plate.
Silicon should be smeared on the piece of liner attached to the fitting, and this can be supplied by your koi dealer when you purchase the fitting.

This photo shows a typical PVC bottom drain for use with a liner.
The holes for the screws can be clearly seen, and the seperate flange can be seen on the floor.
In general they have a deep large sump usually 10 to 12 inches diameter and about 6 inches deep. These usually have a 4 inch socket to take pressure pipe and this is then taken directly to the drain box where a 4 inch stand pipe with `O' ring is fitted.
There are also some available that can be used with ordinary 110mm soil waste pipes.

This photo shows a power skimmer being fitted into a concrete block pond, and this has the plate and screws which are used to attach it to the liner in the same way as the other fittings on this page.

This photo shows a close up of the previous photo, and here you can clearly see the plate and screws which will be removed to fit the liner, and then will be replaced with silicon also being used on the connecting faces.