How to Build Garden Fish Ponds Using Pond Liner
For larger ponds use black plastic liner designed for pond building. Do NOT use a liner if your animals like to swim in the pond. An important point with liner is to ensure that the exposed liner above the pond surface is protected from continuous direct sunlight by creating an edging that will shade the exposed liner surface.
1.1.1 Shapes and sizes for diy ponds
In deciding the shape of the pond take a hosepipe as above. View it from a distance; can you see it from your house? Can you sit close to it? Are there no sharp corner or edges? Is the ground level? No large trees nearby?
1.1.2 Using A Liner initial considerations
It is important to measure your liner properly before ordering. Use the method outlined below to decide what size liner you need to buy to fit your desired pond dimensions (all liner comes in square or rectangular form). You can buy liner here.
First of all the width of the liner:
you need to know the width of the final pond at its widest point and add at the very least 60 cm for edging. You must then also add the depth and the depth again.
For example if you want a pond 2 metres wide and 1 metre deep the width of liner will be 2+1+1+0.6 (for edging) = 4.6 metres.
For the length repeat this process.
All liner ponds will have folds or pleats of liner within them as you can see in the next picture. Do not let this bother you because after a while you will not notice the folds which will become even more disguised as beneficial algae will build up on the sides of the pond.
1.1.3 Pond Depth
You will often be told that a pond should be at least 1 metre or more deep. This is quite simply wrong for many garden situations. Unless you want a large pond and you have a particular interest in wanting to grow large fish then a depth of between 35 cm and 60 cm is perfectly adequate for a basic garden pond.
1.1.4 Dont Forget The Shelves
Whatever type of pond you install ensure that you create a couple of shelves at different levels to accommodate later planting of aquatic plants. Some plants prefer a deeper planting than others. Water lilies for example do best in deeper water say 40 cm. Others prefer to be just submerged, and bog plants like to have their feet wet most of the time.
1.1.5 Installing A Liner Pond
Use a spirit level as shown in the sketch below. Do take trouble here.
Step 1 dig down to the first shelf level
Step 2 if you need a second shelf then dig down to this level allowing an adequate width for the shelf
Step 3 dig out the centre until you reach the desired depth. You will be adding an underlay to protect your liner from stones and sharp objects so make the excavations of the shelves and centre depth some 5 cms more to allow for a layer of sand.
Step 4 once you are happy with excavations place layer of clean damp sand to cover complete excavation. Buy some underlay designed for ponds or use some similar material to lie on top of the sand. This is an extra protection for your liner you do not want leaks later. Some people use wet newspapers as the underlay or old carpet.
Step 5 smooth the liner out as well as possible. Place heavy stones around the edge to keep the liner in its place as you fill with water.
If you find the liner is stretching too much as you fill with water (it becomes thinner as it stretches) release some of the material under the stones. As the pond fills move around the edges tidying up the pleats as much as you can. Stop filling short of the edging area especially if you intend to use an edge for planting as in following sketches.
Step 6 Edging; leave for about a week before starting to allow final settling to take place. You can use SMOOTH rocks for edging as shown (please take care to ensure edge of the liner itself points UPWARDS to prevent siphoning when pond is at high level (after rain for example). Tip take soil from underneath the liner to allow each stone to fit snugly.
You can even plant the edges as shown below
Or use conventional edging materials as below
Ensure the edging overlaps the pond by about 5 cms (to keep the liner in the shade to prevent sunlight degradation). Note that liner points up to prevent siphoning.