A pond is a wonderful way of breathing life into a garden, attracting insects, amphibians and birds that would be nowhere to be seen if you didn’t have this area of water on your patch. The most environmentally friendly ponds will be those that work with nature and don’t rely on plastic bottles full of chemicals to keep the water clear. And if you’re ready to make a new pond you have the chance to use an eco-friendly liner, or even use your natural soil conditions to hold the water.
Making a pond
If you are making a new pond, it’s the perfect opportunity to do it plastic-free! Choose an eco-friendly, non-toxic pond liner, but if you have very heavy clay soil, then it may hold water without a liner if the soil is free from sand and stones.
To increase the chances of your pond being a wildlife haven, leave a slope on one side of the pond, with a pebble ‘beach’ around the water’s edge if possible so that wildlife can easily get in and out of it. And to make it a haven for pond-dwellers, make sure it is at least 40cm deep and ideally 75cm deep at the deepest point if possible.
To fill the new pond for the first time it’s best to use saved rainwater from a water butt because nutrient-rich tap water can encourage the build up of algae. This makes autumn an ideal to start a new pond, when rainwater is less precious and hopefully becoming more plentiful.
Use a solar pump
A pump is a pond essential, preventing the water from becoming stagnant by circulating it which improves the oxygen levels, keeps it clear, removes debris and helps to prevent the build up of algae. As well as not looking great, algae also reduces oxygen levels in the pond which will affect the creatures living in it. And for a small pond, a solar-powered should do the job with no electricity needed to charge a battery or run the pump directly. There are also wildlife protection nets available which reduce the size of particles that are able to enter the net.
Clear the water naturally
Shade from overhanging plants will help reduce algae build up as will not using fertilisers on the plants surrounding the pond. And the best way to not be dependent on plant foods for the plants around the margins of your pond is to pick plants that will naturally thrive in the situation. Choose native plants such as yellow flag iris (Iris pseudoacorus) which is suitable for a large pond and watermint (Mentha aquatica) which suit boggy soils around the pond edge.
Rather than using an ‘off the shelf’ product in a bottle to keep the water clear, try putting barley straw (in a bag or inside some netting) in the water instead. It acts best as a preventative. Use around 50g per square metre of water and as it breaks down it naturally produces hydrogen peroxide, which is harmful to algae, inhibiting growth. Replace it every few months, when the straw has turned black.
Hold back on water
Also go easy on topping up the water levels unless you have fish in the pond. Fluctuations in water levels is a natural thing and too much intervention from the gardener can be unhelpful. Save the precious water in your water butts for thirsty plants elsewhere in the garden instead rather than trying to refill an established pond yourself.
Rehome the fish
If you’re a fish lover then the best way to home and admire them is in a dedicated fish pond rather than pond that you want to be a haven for wildlife and planting. Fish will eat a lot of the pond life, and encourage blanketweed and algae because they raise the nutrient levels in the pond. You will also have to use a lot more water if fish are in the pond, as they aren’t able to cope with a falling water level.
Get rid of the invaders
Ponds can end up being home to an army of invasive non-native pond weeds, including submerged oxygenators Canadian pondweed (Elodea canadensis) and Elodea nuttallii (Nuttall’s waterweed). While ponds need oxygenators that grow underwater to absorb minerals and absorb carbon dioxide to help keep water clear, as well as providing wildlife breeding areas, if they are overly vigorous, they will reduce the biodiversity of your pond. Use a rake to reduce the spread of these plants and remove the plant growth from the water completely because rotting plant material will reduce oxygen levels in the water.
You can also cut oxygenators to reduce their spread if safe to do so but notorious invasive weed New Zealand pygmy weed will regrow from tiny cut pieces of stem so it’s best to carefully pull it out by hand if possible.