Frequently Asked Questions
Should I put goldfish or koi in my pond?
While you can put goldfish into any pond, koi require a good filtration system and a greater volume of water in which to grow to full size. So it is best to plan your pond according to the type of fish you want to keep.
What pump should I use for my pond?
You can use a submersible or surface pump for your pond. The exact type you choose will depend on whether you want to circulate water for a water feature like a fountain or whether you need it to power some sort of a filter, or both. Make sure the pump you choose is suitable for the use to which it will be put. Please also refer to our articles section on water pumps.
What size pump is most suitable for garden ponds?
If you need a pump to operate a filter, the size pump you use in your pond will depend on the volume of water that needs to be moved. This, in turn, will depend on the size of your pond. However, you can use a relatively small submersible pump in a large pond if you simply want to create a fountain feature. For fountains, it is the water head or height that the water will spurt that is important.
What construction method is best suited to koi ponds?
Generally koi ponds are larger than goldfish ponds to allow the fish to grow to full size. This means that preformed ponds are not suitable. But you can build a koi pond using most other, more versatile, construction methods including using concrete, bricks or blocks and mortar, or a flexible liner like EPDM. Please also refer to our articles section on All you need to know about Building a Pond.
Will I need a filtration system for my backyard pond?
If you are going to keep koi fish it is vital to use a good filtration system (preferably a biological filter) to keep the pond water clean, clear and healthy. Many people who keep ordinary goldfish do not bother about filtration, but it will help prevent the water from becoming green and murky.
Is aeration of fish pond water necessary?
If you keep koi then both filtration and aeration of the water is essential, to keep the water clear and healthy, and to oxygenate the water and get rid of toxic gases that build up, particularly in larger ponds. A fountain placed within a pond will help aerate the water. Or you can buy a dedicated aeration unit that either floats and bubbles or sprays from the surface, or a bottom-based unit that pushes air to the bottom of the pool so that it bubbles up again.
What happens if a pond with a flexible liner springs a leak?
Unfortunately this is a potential hazard with flexible liners. Better quality liners, including butyl rubber and EPDM, are usually sold with repair kits, but you may need to drain the pond to locate the hole and fix it.
How can I be sure a concrete pond will remain watertight?
First of all, use a high strength concrete mix – sand, cement and stone mixed 1:2:2 by volume with just enough water to make it workable. Use a small sized stone and add a waterproofing compound to the concrete mix. Once the concrete has cured (at least a week, during which time you should hose it lightly with water every day), plaster the shell and then seal it with rubberized bitumen or a layer of fiberglass.
What is the difference between a mechanical filter and a biological filter?
A simple mechanical filter will filter out dead plant matter, dirt and algae while a biological filter will start a process that results in the breakdown of this waste and debris, keeping the water clear and healthy.
What sort of plants should I grow inside my fish pond?
Various oxygenating plants, available from outlets with fish pond supplies, grow submerged under the water and help to keep the water clear by maintaining the balance of nature. Various floating plants help to suppress algae growth by keeping sunlight out, as do various other aquatic plants like water lilies, pond lilies and lotus plants. Some marginal plants can be grown in shallow water. Where possible choose plants indigenous to your region.