Pond Setup GuideUK garden ponds, sized properly

UK garden ponds

Plan the pond before you buy the pump

Work out the litres, the liner and the flow rate for a wildlife pond, goldfish or koi. Child safety comes before the shopping list.

Plan your pondChild safety
WildlifeNo fish

A beach edge, native plants and rainwater. A filter is usually unnecessary.

 FishGoldfish or koi

Half the volume per hour for goldfish. The full volume per hour for koi.

 Already greenPea soup or blanketweed

They are different problems. A UV clarifier helps only one of them.

Pond planner

Volume, liner, pump, filter, UV and a rough electricity cost. The sums are on this page. Nothing is sent to a server.

Default price: 26.32p/kWh, the Ofgem Direct Debit average for England, Scotland and Wales from 1 October to 31 December 2026. Your tariff and region can differ. Standing charges are not included.

Plan

Size, site and line the pond before you dig.

Size and depthHow big should a garden pond be?

RHS depth and surface-area figures for a UK garden pond, plus shelves, a beach edge and a worked example.

Liner sizeWhat size pond liner do I need?

The liner sum used for UK ponds — length and width plus twice the depth plus overlap — and why underlay is not optional.

CalculatorPond planner

A browser calculator for pond volume, liner size, pump flow, filter rating, UV watts and yearly running cost.

Preformed or linerPreformed pond or a liner?

When a rigid shell is enough, and when the RHS points you to a flexible liner and a beach.

SitingWhere should a garden pond go?

Sun, shade, trees, buried services and child access, using RHS siting advice for a new UK pond.

Kit

Pump, filter and UV sized from the pond you have.

Filter sizeWhat size pond filter do I need?

Pressure filters and box filters, and why the fish rating on the box matters more than the biggest litre number.

Pump flowWhat size pond pump do I need?

PondXpert's goldfish and koi flow rates, how head height cuts the real flow, and two Oase pumps with maker figures.

UV wattsWhat size pond UV clarifier do I need?

How a UV clarifier clears green water, and the Hozelock Vorton wattage and flow bands to start from.

Wildlife

A pond for amphibians and insects, without fish.

Wildlife pondHow to build a wildlife pond

RHS steps for a UK wildlife pond: no fish, a shallow beach, rainwater, and a way for animals to climb out.

Pond plantsPlants for a wildlife pond

The four plant roles the RHS names for a UK wildlife pond, and the invasive-plant warning that comes with them.

Safety

Children first, then the electrics.

ElectricsPond pump electrics

What Electrical Safety First and the RHS say about RCDs, cables and using a qualified electrician for a pond pump.

Child safetyPond safety for children

RoSPA's grille, fence and fill-in options for a UK garden pond, and why a leaf net is not a child cover.

Fix

Tell green water apart from blanketweed.

BlanketweedHow do I deal with blanketweed?

What the RHS says about blanketweed in a UK pond, why a UV clarifier often misses it, and how to remove it without emptying the pond.

Green waterWhy is my pond water green?

Suspended algae, the RHS distinction from blanketweed, and when a UV clarifier is the tool that helps.

Care

Winter, leaves and topping up.

WinterPond care in winter

Leaf nets, ice, and what the RHS says about pumps and open water for fish and for wildlife ponds in the UK.

RainwaterTopping up a pond with rainwater

Why the RHS prefers rainwater to the hose, and when a wildlife pond can be left to drop in summer.

Around the garden

Sister guides

Sister sitePlankley

Digging, edging and paving around the pond.

Sister siteGladeburn

Robot mowers, and keeping them off the pond edge.

Sister siteRowanspring

How much rain a roof can put into a water butt.