How To Keep Your Pond Healthy

Keeping a pond healthy requires a combination of nature and technology right from the planning stage to create a haven for plants and animals.

This guide will help you achieve a pond that enhances your garden with its appearance and also becomes a thriving wildlife sanctuary. At the planning stage there are simple rules to follow when placing a pond in your garden. Position it away from trees to lessen the chances of leaves falling into the water, but shaded from direct sunlight for a good portion of the day. Make sure the water is at least 2ft deep, ideally 3ft - 4ft if you are keeping fish, with marginal shelves for plants.

Maintaining Good Water Quality

Once in place you need to ensure that excellent water quality is maintained to encourage a flourishing environment for plants and wildlife. The water should circulate and oxygenate rather than stagnate. The ideal way of achieving this is to introduce a water feature such as a fountain or waterfall.

To calculate the size of the pond pump you require to feed the feature remember that water should be circulated at least once every two hours i.e. a 300 gallon pond will need a pump that generates a flow of 150 gallons per hour.

Next consider what you are asking the pump to do and bear in mind that it always pays to buy a pump with a capacity above what you need, as you may want to add features at a late date.

To be absolutely sure that you get the right pump for the job, arm yourself with these facts, refer to manufacturer’s specifications or ask advice at your garden centre:

  • The volume of water in the pond
  • Total head height of any fountains and waterfall the width of any waterfall, the total length of hosing used
  • Filtration is also essential to prevent the build-up of nutrients and impurities and ensure clean, healthy water.
  • Mechanical filters trap dirt and debris, effectively cleaning the water of elements that may feed algae or are otherwise harmful to pond life.
  • Biological filters provide a medium in which beneficial bacteria can multiply and break down harmful toxins such as ammonia resulting from fish waste..
  • Chemical filtration is also effective against non-filterable pollutants and refers to the process of controlling and changing specific water conditions so that, for example, phosphate and nitrates are trapped and eliminated.
  • Finally UV clarifiers kill algae before it spreads and are particularly effective against ‘green water’

As these processes can be combined, for example filter kits may contain mechanical and biological filters together with a UV clarifier and they come in a range of formats such as pressure filters, gravity fed filters, pre-filters, specialist koi filters – it is no surprise that the choice is daunting.

Standard box filters are available for ponds containing 1000 – 10,000 litres, they can be mechanical and biological, with or without a UV clarifier fitted. Pressurised units allow you the option of powering a waterfall or fountain and more expensive filters feature advanced technology and can handle larger volumes of water.

When choosing a filter, consider what is most appropriate for your particular requirements. Follow the manufacturer’s recommendations on the filter’s capacity and the volume of water it can process. Don’t forget that if you have fish, take into account how many and how large they are, as this can dramatically affect the specification that is required.

Green Water

If you have green water then you will need to add a UV clarifier and filter. The UV light will burn the suspended algae particles which cause the water to look green and then they are filtered out of the water. This process can take up to two weeks after installation.

A chemical such as Blagdon Green Away can also be used, this works by clumping the green water particles together allowing your pump to send them into the filter for easy disposal.

Perform a Water Change

Changing the water is a good way to keep your pond fresh, adding more nutrients for the plants to feed off. The downside is that algae also feeds off these nutrients, so make sure you have a good balance of plants to help prevent this.

When the water is changed, clean out your filter with the water you removed from the pond in the first place. Clean the foams and media and then replace them. Do not rinse them under a tap as the chlorine in tap water will kill all of the beneficial bacteria.

It's always wise to test the pH of the water at regular intervals. Pond ph test kits are cheap to buy and easy to use to discover if the water is unbalanced. If remedial action needs to be taken, there are a range of treatments available to rectify any problem.

Add a Fountain Pump

Adding a fountain pump to aid oxygenation will help to keep the pond clear due to the increased friendly bacteria levels as they thrive in oxygen rich water.

Planting Is Important

Aim to have a good variety of plants. These are not only decorative but help to keep the pond in good shape.

Algae depend on sunlight, carbon dioxide and dissolved minerals for survival, so use water lilies and similar floating plants to cover about half the surface, shading the pond from sunshine. Submerged oxygenating plants will also reduce algae by absorbing minerals and carbon dioxide from the water.

If algae does invade the pond, remove as much as you can with a stick or net and then treat with a wildlife-friendly algae treatment such as Barley Straw extract that will either kill the algae or remove the nutrients that the algae feeds on. Once eliminated, your water pump and filtration system should prevent any re-occurrence.

Prevent foliage from falling into the water (netting is useful in the autumn) and remove any rotting organic matter such as dead leaves from the pond as the gases released by decaying foliage are harmful to plant and wild life especially if they become trapped by winter ice.

Too Many Fish

The nitrate content of your water will increase if you keep fish, so don’t overstock. A rule of thumb is one inch of fish per sq ft of surface area (or 25cm per sq metre). Remember it’s always better to have a few fish rather than too many, especially in the summer when there is less oxygen in the water.