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Pond Care 101

How to care for your garden pond


Whether you have inherited a pond or have designed and built your own, we hope that these tips will help you find water gardening as rewarding as we do.


RESEARCH     Give yourself some background knowledge on what makes a successful pond and how to avoid some common pit-falls, and you can avoid expensive and frustrating mistakes!  There are lots of very good resources online and some good pond-building tips on YouTube. Be very careful with online forums, blogs and Facebook groups as it can be hard to separate the genuinely sound advice from old-wives tales and hearsay!

LITTLE & OFTEN    Treat the pond as you do the rest of your garden. Most gardeners spend a little time here and there maintaining their plants and weeding, and the pond should be approached in the same way.

MEASURE    Calculate the volume of your pond. At some point you may need to      medicate your fish or add a conditioner or fertiliser, and you will need to know the volume to calculate the dosage. Measure the average length, width and depth of the pond in      metres and multiply the measurements together. This gives you the volume in cubic metres. Times this by 1000 to work out how many litres you have. (e.g. for a pond which is 2m long, 3m wide and 1m deep: 2 x 3 x 1 = 6m3. 6 x 1000 = 6000 litres.)

TAP WATER  Remember not to top up your pond with water straight from the tap.  Tap water contains chlorine to kill bacteria and make it safe for us to drink.  Unfortunately this also damages the beneficial bacteria and micro-organisms in the pond, and can make your fish ill. Always treat tap water with a water conditioner or ‘dechlorinator’.

FEEDING FISH  If your pond has fish in it, it is VITAL that you do not overfeed them. Just like dogs, they will beg for food whether they genuinely need to be fed or not! Dried fish food is very concentrated and high in protein. Feeding too much can lead to algae  problems, cloudy water and ill or dying fish. Koi and goldfish don’t have stomachs as such; the food is digested in the intestine, so they can only process a tiny amount of food at a time. If they eat more than 2-3 pellets per meal, most of it will just come out as undigested waste so larger portions of food just waste your money and make it harder for you to keep the water quality stable. During the summer months you should feed a good quality food once or twice a day as fish need to eat more to store up fat to help them survive the winter.  In winter they must be fed with an easily digestible “wheatgerm” based food. This is       because their metabolism slows down so much in the colder water that they cannot digest the high-protein summer food.

STOCKING  Do not be tempted to over-stock your pond. Bear in mind that most fish you buy will be juveniles and will grow to many times the size they are now! The more fish you have, the more waste will be generated in the pond, and the more likely you are to have problems with the water quality and/or algae blooms.

CLEANING    Try and maintain your pond by giving it a PARTIAL water change at least once a year. We hire out a Pondovac, which is a large vacuum cleaner designed to  remove sludge and debris from the bottom of the pond without disturbing your fish. As you are not removing more than about 30% of the total volume of water, you will not be      disrupting the chemical and biological balance of the pond.

ALGAE  Be prepared to encounter algae! You WILL get this at some point! It is a    natural, primitive plant that actually helps to keep the pond healthy. The two most     common forms found in a garden pond are unicellular (tiny particles of suspended algae which make the water appear green) and filamentous algae i.e blanket weed (long strands or tufts of algae which grow on the plants and sides of the pond) There are many ways to combat algae:

MORE PLANTS!      Plants feed on the same nutrients in the water as algae does, so your plants help to compete with and starve the algae. Any plants which grow loose in the water will help as the roots take the nutrients directly out of the water (whereas plants in pots will be getting their nutrients from the compost).  Algae growth is stimulated by sunlight, so floating plants and lilies provide shade– ideally you should aim to have       over half of the surface of the pond covered in plants. This restricts the amount of light entering the water, and makes the pond look more attractive. Plants also help to use up fish waste by-products in the water, so they will improve your water quality.

ANTI– ALGAE PRODUCTS  These products aren’t necessarily intended to ‘kill’ the  algae (you wouldn’t want decaying algae matter in the pond as it would pollute the water) but they should stop the algae growing back once you have manually removed as much as       possible. In the case of unicellular algae, the algaecide damages the algae cells and makes them flocculate or ‘clump together’ so they are removed by the filter.  Use algaecides as a last resort and try not to use them in spring when wildlife is relying on algae for food and protection.  Barley straw is a natural slow-acting algae treatment which can be added in spring to restrict algae growth.

FILTRATION           A filter is vital to keep your pond clean and clear. It reduces      maintenance, improves the water quality for your fish and if you add an Ultra Violet light unit to your filter, it will remove the green suspended algae from your water. The pump supplying water to the filter can also be used to run a waterfall, which oxygenates the  water for the fish and improves the general appearance of the pond.

COLD WEATHER      During the autumn, try to remove any dying leaves from your pond plants (most will re-grow next spring) and cover the pond with a net to prevent leaves and debris from falling in. Leaves can rot in the pond over winter and cause    problems with the water quality. If the weather is particularly icy, it may be safest to    install a pond heater to prevent ice forming on the surface and suffocating the fish. Never try to break the ice as the shock–waves can stress the fish!

Fish are at their most vulnerable during the winter. Keep an eye on the water quality– most pond medications will not work if the water is below 10°C so prevention is better than cure. If you do need to treat your fish during the winter, you may need to separate the ill fish and move them to a quarantine tank inside.

Re–position your pump during the winter. It is best to keep your pump and filter running throughout the winter but move it so it is higher in the pond and will not disturb the warmer water at the bottom. The fish are dormant at the bottom of the pond in very cold weather and they need the temperature to remain as constant and warm as possible while they hibernate.

PREDATORS    If you choose to keep fish in your pond it is your responsibility to make sure they are protected from predators, ideally with a secure cover net.

GO STEADY!    Never completely empty your pond! You will upset the pond’s balance and this always does far more harm than good.  Test your water regularly (bring a sample to us if you don’t have your own testing kits) and talk to us if you’re having problems.


Good luck, and enjoy your pond!




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