On a gravity-fed run or behind a small pump, pushing the pipe onto the barbs of the fitting is enough. Behind a powerful pump, add a hose clip on each end. To push the pipe on more easily, dip its end in hot water for 30 seconds: the PVC softens and slides over the barbs more readily.

Roll of flexible 16 mm pipe, white on the outside and black on the inside

Flexible 16 mm double-layer pipe, white and black

Name: Flexible 16 mm double-layer pipe, white and black
Brand: Growrilla
SKU: TU-PVCGFP16-5
Price: 3100.0 JPY
Availability: InStock

¥3,100

¥1,033 × 3 with no fees Klarna.

This flexible 16 mm pipe carries the nutrient solution away from the light: its white outer layer reflects the heat of the lamps and the sun, and its black inner layer stops algae from settling. It fits all 16 mm barbed fittings and is sold in a 5 m roll.

Ref. TU-PVCGFP16-5·Pipe

Longueur : 5 m

5 m

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The summary

What it is: a flexible PVC pipe, white outside and black inside, for circulating a nutrient solution.
Its diameters: 12.5 mm inside, 18.5 mm outside, for 16 mm barbed fittings.
Where it is used: between a reservoir and a float valve, on a pump intake, for irrigation.
The format: a 5 m roll, which you cut to the lengths you need.

Flexible double-layer pipe for the nutrient solution, on 16 mm barbed fittings

A pipe that lets light through ends up turning green on the inside, and a black pipe laid under a lamp warms the solution it carries. This 16 mm flexible pipe solves both problems with its two-layer construction. It connects the elements of a hydroponic installation or an irrigation network, and you cut it to the length of each link before pushing it by hand onto barbed fittings.

🌗 Two layers, two roles

The outer layer is white: it reflects sunlight and the light from grow lamps, which limits the heating of your solution in the pipe. The inner layer is black and blocks light, without which algae cannot develop in water laden with nutrients. A transparent pipe, by contrast, lets light through and ends up turning green on the inside, whatever the quality of the solution flowing through it.

🌡️ A cooler solution

The temperature of the solution determines how much oxygen it can dissolve. At saturation, water at 20 °C holds 9.1 mg/L, compared with 8.3 mg/L at 25 °C and 7.6 mg/L at 30 °C, while roots breathe more when it is warm. Above 26 °C at root level, the risk of infection by Pythium, an organism responsible for root rot, also increases. Every metre of pipe exposed under a lamp or in the sun warms the solution passing through it; a sleeve that reflects light limits this heat gain.

The float valve for automatic top-up

With this pipe and the float valve, your control pot refills by itself from a top-up reservoir placed beside it. The valve opens when the level drops and closes again once it is restored, so you can be away for a few days without topping up yourself, as long as the top-up reservoir holds enough solution. That leaves just one level to watch, that of this reservoir.

🔧 The 16 mm fittings

The pipe has an inner diameter of 12.5 mm and an outer diameter of 18.5 mm, and it slides onto all 16 mm barbed fittings. In an RDWC network, it connects the top-up reservoir to the float valve of the control pot, and it serves as a suction pipe for the solution. The 32 x 16 mm valved fitting has a 16 mm barbed outlet, onto which it fits directly. You then push it on by hand, right to the bottom of the barb, with no glue or tools.

🐟 In an aquaponic system

In aquaponics, this pipe carries pond water, rich in nutrients from the fish waste, to the grow beds or to the top-up reservoir. Its opacity stops algae from colonising the inside of the pipework, where they would reduce the usable cross-section and consume oxygen at night. In summer, the white outer layer also limits how much the water heats up on runs exposed to the sun, which matters for your fish, since water loses oxygen as it warms. The guide to maintaining an aquaponic system in summer covers the other jobs for the hot season.

📦 One 5 m roll

The pipe is supplied as a 5 m coil, which you cut to the lengths of your connections. Measure each run before cutting, leaving a little slack at both ends, so that the pipe does not pull on its fittings when you move a pot or the top-up reservoir. The same pipe can also be used for ground-level irrigation, between a rainwater tank and a drip line, since it pushes onto the common 16 mm barbed fittings.

Technical specifications

The essentials

Internal diameter: 12.5 mm
Outer diameter: 18.5 mm
Fittings: Ribbed, 16 mm
Length: 5 m, to be cut to length

Construction

Material: Flexible PVC
Outer layer: WhiteIt reflects the light and limits the warming of the solution.
Inner layer: BlackIt blocks out the light, and the algae with it.
Origin: Italy

In the box

1 roll of 5 m of flexible double-layer pipe, white and black.

Diameters, construction and uses taken from the manufacturer's product pages, on 08/10/2026. Dissolved oxygen: USGS saturation tables. 26 °C threshold: Grodan growing guide.

Estimate your
delivery time

The pipe is shipped coiled, in a compact parcel. Dispatch is from the workshop in Robassomero, near Turin. The exact charges and final delivery times are displayed at checkout once the address has been entered. Outside the European Union, import duties and taxes are payable by the recipient.

Frequently asked questions

8 questions

6 key questions, 8 in the detailed view

Which fittings does it attach to?

Why a white and black pipe rather than a black one?

Is it a 16 mm drip irrigation tube?

Can it be bought by the metre?

Where does it go in an RDWC system?

Is a clamp required?

Can it also be used for watering in the garden?

How do you cut it cleanly?

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Flexible 16 mm double-layer pipe, white and black

The summary