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Garden Ponds: Filters, Pumps and Liners for Pond Fish

What a garden fish pond needs compared with an aquarium: a liner, a pump and a filter sized for the pond, water testing, and fish that never go into the wild.

By Fish Supplies editorial teamUpdated 2 min readHow we research

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A garden fish pond needs the same three things as an aquarium, scaled up and moved outdoors: a watertight liner, a pump to move the water, and a filter sized for the pond’s volume and its fish. Test the water as you would in a tank, and never let pond fish or plants reach a stream or lake.

This section covers the gear for an outdoor pond. Many of the water rules from our aquarium chapters carry over, so the links below point to them where they do.

What a pond has in common with a tank

A pond is still a closed body of water that has to process fish waste. Goldfish, the most familiar pond fish, make a lot of waste, so the filter matters as much as the size. Our goldfish tank setup chapter explains why, and RSPCA Australia says goldfish can live about 10 to 15 years, so a pond is a long-term home.

The same bacteria-driven nitrogen cycle that keeps a tank safe works in a pond filter. How to cycle a fish tank explains it, and a test kit tells you whether it is working.

Water test kits and conditioners

Shop water conditioners, test kits and bacteria starters

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Pond gear compared with aquarium gear

Job In an aquarium In a pond
Holding the water Glass or acrylic tank A liner or a preformed shell
Moving the water The filter’s own pump A separate pond pump
Cleaning the water Hang-on-back, canister or sponge filter A pond filter sized for the volume
Light A light on a timer Daylight, with shade from plants

Aquarium filters compared explains mechanical and biological filtration, which is the same idea at pond scale.

Keep pond fish out of the wild

Pond fish and plants do not belong in natural ponds, lakes or streams. The Habitattitude campaign, announced by the U.S. Fish and Wildlife Service, suggests returning unwanted animals to a retailer, giving them to another hobbyist or a club, and sealing unwanted plants in a bag for the trash. Place a pond where a flood or overflow cannot carry fish into a nearby creek.

Aquarium chapters that apply to ponds

Two orange goldfish swimming in a dark, planted aquariumGoldfish needsSpace, filtration and temperature for goldfish.
Zebra danios swimming beside a filter outflow pipe and a stream of bubbles in an aquariumHow filters workMechanical and biological filtration explained.
A newly planted cube aquarium under a clip-on light, with no fish yetThe nitrogen cycleHow bacteria make fish waste safe, and how to test.

For water changes and routine jobs, see the tank care section.

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