Autumn leaves may look colourful and are fun for children to gather in piles or kick around the garden but their attractive and playful nature hides a unfortunate secret.

If you allow leaves to fall to the bottom of the pond they will rot, releasing nitrates and noxious gases into the water harming fish and plant life, and all sorts of disagreeable reactions take place to threaten the crystal clarity of your pond water.

What you can’t see is the chemical balance of the water altering, some leaves such as oak will result in acidity levels rising, Immediately apparent will be tannins changing the colour of the water to resemble builders’ tea and nutrients will encourage algae to develop in the spring.

Other toxic gases such as methane are released and the problem increases during the winter when ice may prevent these gases from escaping, having potential lethal results.

Although ponds should be positioned away from trees and hedges, it is inevitable that leaves will be blown onto the water, and the best way of preventing this happening is to use netting. Placed over the surface of the water, netting will catch leaves and preventing them from entering the pond.

Netting will also protect fish from predators such as herons and cats, and once plants have grown through, the netting largely disappears from view.

a pond with netting

Jobs to do before netting

Trim back any aquatic plants, you don’t want their foliage taking the place of the leaves you are discouraging.  At the same time, you might like to divide any plants that are becoming too large before they take over the pond, although this could wait until the spring if they are not early flowering.

Any debris that the pond has collected during the year should be fished out with a net. Bear in mind that it’s worthwhile leaving the cuttings and salvaged material next to the pond for a while so that any aquatic invertebrates can creep and crawl back into the water.

Remove any filters and pumps, clean and store them away safely when the temperature drops below 10ºC. Any biological activity will have slowed down drastically by then with fish and frogs retreating to the depths of the pond where they don’t want to be disturbed.

To stop ice forming, a wildlife friendly ice prevention solution can be effective even when the temperature dips to -6ºC. You can consider a heater perhaps operated by a thermostat, these are fairly economical to run as are air pumps that also reduce carbon dioxide levels during the summer.

What netting is available?

Excellent quality netting is available from leading brands Oase, Hozelock, Lotus and Velda, starting at 2mtrs x 3mtrs and available in set sizes up to 6mtrs x 10mtrs. Lotus netting can also be bought in metre lengths from 3 or 6 metre wide rolls. Set sizes will be delivered with the appropriate pegs to fix the netting in place.

Any netting will prove to be a long term investment, protecting the pond from leaves and predators. However, Kid Safe Child Safety Netting will be a sensible alternative if there are children around. Nothing replaces adult supervision but this type of netting gives you peace of mind. Available in a variety of sizes, the net is 4mm high density polyethylene braid which is UV stabilized to prevent shrinkage and is attached to the pond surround with brass anchors and carabiner clips.