Clear blue flexible pipe 14 x 18 mm, shown in cross-section

Opaque white two-layer pipe, 4 x 7 mm, for air and nutrient solution

Roll of black flexible pipe 18 x 22 mm sold by the metre

Roll of 14 x 18 mm blue crystal pipe, cut to length at the time of ordering

Flexible PVC pipe by the metre or on a reel, 3 diameters

Name: Flexible PVC pipe by the metre or on a reel, 3 diameters
Brand: Terra Aquatica
SKU: TA-TUYAU-4X7
Availability: InStock

$3.00

$1.00 × 3 with no fees Klarna.

This flexible PVC pipe is sold by the metre in three diameters, matching the hydroponic systems in the same range: 4 x 7 mm opaque white, 14 x 18 mm crystal blue, and 18 x 22 mm black. The quantity ordered corresponds to the number of metres, supplied as a single length.

It is used to replace a worn connection, extend a circuit, or build a custom system.

Ref. TA-TUYAU-4X7·Pipe

Diameter : 4 x 7 mm, white

4 x 7 mm, white

14 x 18 mm, crystal blue

18 x 22 mm, black

Packaging : Per metre

Per metre

Customer support 7 days a week by email

Delivery within 2 to 15 business days

100 % secure payment

The summary

What you receive: a single continuous length per metre, or a 50 m roll in 14 x 18 and 18 x 22 mm.
The 4 x 7 mm: opaque white, for air lines and small solution runs.
The 14 x 18 mm: blue crystal, for gravity-fed connections and level tubes.
The 18 x 22 mm: black, for feed manifolds and water returns.

Replacement pipe sold by the metre for water, nutrient solution, and air circuits

This flexible PVC pipe is sold by the metre in three diameters, matching those used in the hydroponic systems in the range: 4 x 7 mm white, 14 x 18 mm crystal blue, and 18 x 22 mm black. You order the number of metres required, supplied as a single length, then cut exactly what you need to replace a worn connection, extend a circuit, or build a bespoke system. The first figure gives the internal diameter, which determines the fitting, and the second gives the external diameter.

📐 Three diameters, three applications

The 4 x 7 mm is a white, opaque, two-layer pipe with a thick wall that resists crushing. It fits onto the 4 mm outlets of air pumps and diffusers, and supplies the nozzles of the aeroponic pot with nutrient solution. Its opacity prevents algae from developing inside, which also makes it a good air pipe for a tank exposed to light.

The 14 x 18 mm is a translucent blue pipe. It connects two reservoirs at different heights by gravity, and it serves as a sight tube, since the water level is visible through the wall. It fits over 16 mm barbed fittings, whose ridges hold it in place without a clip on a connection that carries no pressure. The 18 x 22 mm, by contrast, is a black, opaque pipe with a larger bore. It is used on the supply rails of gutter systems and on water returns to the reservoir, wherever flow rate matters. Under pump pressure, it is secured to its fittings with hose clips, and its black colour protects it from light along its entire length.

Connecting an air pump to its diffuser

The 4 x 7 mm pipe fits directly onto the 4 mm outlet of an adjustable air pump and onto the connector of a diffuser. Cut the exact length needed between the pump, positioned out of the water, and the bottom of the tank. The opaque pipe stays clean far longer than a transparent one.

Keep the nutrient solution away from light

Crystal-clear pipe lets light through: a nutrient solution left standing in it will turn green within a few weeks. Keep it for plain water, short connections, and sight tubes, and choose an opaque pipe for nutrient solution circuits exposed to daylight.

✂️ Cut and fit

Cut the pipe cleanly and squarely with a knife or pipe cutter, as an angled cut will cause a leak at the fitting. To push a stiff pipe onto a barbed fitting, soak the end in hot water for 30 seconds: the PVC softens and slides more easily over the barbs. Leave a gentle curve rather than a sharp bend, which constricts the bore, and you will be able to disconnect the pipe later without having to cut it.

🐟 The pipe in aquaponics

In an aquaponic system, the 18 x 22 mm size is suitable for the water return from a grow bed to the pond, and the 4 x 7 mm for aerating the fish tank. The 14 x 18 mm serves as a level tube on a sump, allowing you to read the water height at a glance, and for feeding a rainwater top-up reservoir.

📦 By the metre or on a roll

The 14 x 18 mm and 18 x 22 mm sizes are also available as a 50 m roll, in one continuous length, for fitting out a complete installation or keeping a supply to hand. Per metre, the roll works out cheaper than cut lengths, making it the better choice once your requirement exceeds around 45 metres. Below that, buying by the metre remains the most economical option, and in either case you receive a continuous length with no intermediate fitting. Bear the weight in mind too: the roll weighs approximately 6.1 kg in 14 x 18 mm and 11.3 kg in 18 x 22 mm.

Technical specifications

The three pipes

4 x 7 mm: White, opaque double-layer41 g per metre
14 x 18 mm: Blue crystal, translucent122 g per metre
18 x 22 mm: Black, opaque225 g per metre
Material: Flexible PVC

The nozzles

Pipe 4 x 7 mm: 4 mm nozzle
14 x 18 mm pipe: 16 mm end fitting
18 x 22 mm pipe: 20 mm end fittingWith a compression collar
Cut: With a cutter, perfectly straight

Sales

Unit of sale: By the metre, or in a 50 m roll
50 m roll: In 14 x 18 and 18 x 22 mm6.1 kg and 11.3 kg
Use: Water, nutrient solution, air
Manufacturing: France

To budget for separately

Air pump: An adjustable air pump
Complete system: A drip system

6 further specifications are available in the detailed view.

In the box

1 length of flexible pipe, as many metres as the quantity ordered, or 1 50 m roll

Diameters, colours, material, weight per metre, and uses recorded on 02/10/2026 from the manufacturer's sheets and the instructions for the CultiMate, GrowStream, and Ebb&Grow systems. Roll weights recorded on 07/10/2026 from the Terra Aquatica 2026 price list.

Estimate your
delivery time

Coiled pipe dispatched by tracked parcel from France. Exact shipping costs and final delivery times are displayed at checkout once your address has been entered. Outside the European Union, import duties and taxes are the responsibility of the recipient.

Frequently asked questions

6 questions

6 key questions

How do you order 3 metres?

Which pipe for which fitting?

Pipe	Barb	Example
4 x 7 mm	4 mm	Air pump, diffuser
14 x 18 mm	16 mm	Barbed fitting, float valve
18 x 22 mm	20 mm	Drip system manifold

Does crystal pipe turn green?

Are hose clips needed?

Can it be used outdoors?

What weight for 10 metres?

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Flexible PVC pipe by the metre or on a reel, 3 diameters

The summary