Response to a customer problem who had already installed a preformed pond but wanted to make it bigger
We are often asked this question by customers wishing to build a larger pond and the answer is relatively straightforward. Basically you need to make a conduit between the two for water to flow through. This can be achieved using a piece of pond liner to create a channel or joining stream.
If the original pond is a preformed pond then it is a little trickier. Where the water is to drain from one pond to the other you will need to make the pond level lower. This will involve making a flat U shaped cut into the rim of the pond using a saw. (Make sure you drain the water below this level first). Once the channel is cut off then sand it down so any sharp pieces do not pierce the pond liner. Use the sandpaper to roughen the area where the pond liner is to be joined so the glue has a ‘key’ to bond to.
Take a piece of pre-cut pond liner at least wide enough for the channel width plus twice the depth + 10%. Make sure the liner is LDPE or rubber and it can be joined to the existing pond onto the channel cut by using cold glue joining tape.
It makes a nice looking effect for one pond to spill over into the other. In this case the pond pump should be placed in the lower pond and should push water back up to the higher ‘header pond’. If the ponds are to be the same level then you may find there are problems with circulation of the water. Basically not all the water will be getting ‘turned over’. In such a case we would recommend using two submersible pumps. Each pond pump to be placed at the bottom of each pond with the water coming back in at the top to ensure circulation.
The piece of stream/joining pond liner should be attached to the second pond - again using cold glue tape as previously advised.