Summer / Weekend projects
How to build a raised pond on your patio
By The Secret Gardener
When we think about patios, we think of sitting out, dining and entertaining or even playing out with the kids. It's where we spend the most time in the garden, so it’s the ideal place to build a raised pond.
Raised ponds add plenty of interest to the garden, and the sound of splashing water is so relaxing. Plus it's a great way to try your hand at growing aquatic plants and keeping fish. Plus, they are better than sunken ponds for people with small children.
I built a lovely raised pond in my garden and I find it fascinating – it's an environment in miniature! It’s also a tranquil spot in the garden.
First, measure the area. Bigger ponds are better because you will have more space for fish. But you can put in a smaller pond in if you're short on space.
For a standard rectangular pond, I would aim for 1.5m x 2m, and 1m deep (50cm underground & 50cm above ground).
Or try an unusual shape! An L-shape is great for a corner space, or an octagonal one will make a great standalone feature.
You also need to consider how deep your pond will be. If you want to keep fish, you have to make sure the water is deep enough for fish to have unfrozen water during the winter months. I would aim for no less than 1m deep.
If you're excavating and laying foundations, dig a hole and remove the soil. Lay down and compact your hard core, and then build a bed of cement on top. Your cement should be 100-150mm thick with a spread of 100mm either side of your brick wall.
Once that's dry, you can start laying the walls. You should use walling blocks for this – Bradstone do a great range.
If you're building a big pond, you will need to use breeze blocks to reinforce the wall because of the weight of the water.
The key to a strong wall is to interlock the bricks at the corners. This is especially important in ponds, because the corners will take the pressure from the water. Some landscapers use corner brackets for additional support to the corner joints.
Finish off the walls with coping stones on the top. This will give you a place to sit or lean on to look into the pond and truly enjoy it. Remember not to cement these in until you have put in the liner!
Now run cement around the inside of the pond walls to make them as smooth as possible. You don’t want any sharp stone edges to pierce the pond liner!
Or, a good tip is to head to your local carpet shop and pick up any offcuts or underlay scraps. It's usually free and can be used to line the inside walls, creating a cushion between the brickwork and the liner.
If you want to grow some marginal pond plants around the edges, place in large blocks as shelves. You can sit the plants on top, allowing them to rest in shallow water.
Pond plants are divided into three groups: floating plants, oxygenating plants and marginals. Try water lilies, iris, lobelia cardinalis, hornwort and starwort.
Now you need to put in the liner. Buy a good quality rubber liner from a garden centre or aquatics supplier and lay it loosely inside the pond.
The trick to getting the perfect lining is to fold and crease it as you gradually fill the pond with water. Work slowly and methodically.
Make sure the liner is well secured at the top of the pond by the coping stones.
Then you need to add in a pump and filtration box. Pumps circulate the water and add oxygen, which is important if you want your fish to survive! It also stops your pond becoming stagnant. Some pumps have an ultraviolet light that keeps the water clean and limits algae.
I usually leave the pond for a couple of days to let the water settle before I introduce fish. Head down to your local aquarium and choose your favourites.
Goldfish are the most popular and easiest to keep. Or try koi carp – they need a little more care and you might need a better filtration system too. Ask at your local aquatic store for advice.
A splashing water feature will add a soothing sound and help keep the pond water oxygenised. Sprays, fountains and waterfalls are great additions to a pond.
Then you can sit and enjoy your new pond feature. Colourful fish, aquatic plants and the sound of splashing water – it's marvellous!
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