Growrilla float valve, white float on an articulated arm, tank connector nut, and black barbed fitting

Diagram of a gravity-fed constant level system: header tank, pipe to the trough, valve and float that opens the inlet when the level drops.

Float valve for automatic top-up

Name: Float valve for automatic top-up
Brand: Growrilla
SKU: SI-GRCKVG01B
Price: 12.9 EUR
Availability: InStock

12,90 €

This float valve maintains the water level in an RDWC system: when the level drops, the float opens the inlet and the solution flows by gravity from a container placed higher up. It works without electricity, connects in 16 mm and also maintains the level of an aquaponic sump or grow bed.

On an RDWC 2.0 kit, it goes in the controller pot, where the network's level is read and topped up.

Ref. SI-GRCKVG01B·Valve and tap

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The summary

What it does: it reopens the water inlet as soon as the level in the circuit drops, and closes it again as soon as the level is restored.
What it requires: a container placed above the level to be maintained, connected by a flexible pipe.
What it doesn't require: you don't plug it into a mains socket, fit a battery or programme anything.
Which system it suits: the control pot of an RDWC 2.0 kit, but also an aquaponic sump or a gravity-fed tank.

Float valve requiring no electricity that maintains the level in an RDWC system or tank

The float valve for automatic top-up keeps the level constant in an RDWC system, an aquaponic sump or a grow bed. It reopens the water inlet when the level drops and closes it again as soon as the level is restored, with no electricity, batteries or programming. A container placed higher up feeds it by gravity, via a 16 mm barbed fitting.

This float valve maintains a constant water level in a circuit or tank by refilling it continuously from a container placed at a higher level. The valve reopens the water supply as soon as the level drops and closes it again once it has returned, with no electricity, no batteries and no programming required.

⚙️ How the float valve works

The valve is a small tap operated by a float. As long as the water supports the float, its arm keeps the valve shut. When the level drops because of evaporation and plant uptake, the float sinks with it, the valve opens and the water from the container flows out. As soon as the desired level is restored, the buoyancy of the float closes the valve again. Without this regulation, a falling level causes two problems.

The pump is drawing air

Its strainer eventually breaks the surface, and a pump that loses prime stops circulating water throughout the entire system, not just in its own pot.

The roots emerge from the water

Their upper section emerges beneath a closed lid, out of sight.

Fitting the container with a tap fitting

To bring the top-up pipe out of a jerry can or a rigid tank, the 32 x 16 mm fitting with valve for RDWC 2.0 goes into a 38 mm drilled hole, with a 32 mm push-fit seal. It gives you a 16 mm barbed outlet with its own tap, which you close during a drain-down of the network so that the jerry can does not empty into an open pot. Choose the elbow version when the can is tight against a wall, because the pipe must not kink.

A bottle sized to your tank's margin

The float must move freely, touching neither the wall nor a root. If it stays stuck in the low position, the whole canister empties into the circuit: so choose a canister whose volume does not exceed what your tank or your pots can still take before overflowing. Also keep this canister closed, as a speck of dust or a leaf reaching the valve is enough to cause a slow leak.

🔗 Where it connects

On an RDWC 2.0 kit, the valve goes in the controller pot, with the float at the surface of the solution: this is where the network's level is read and topped up, and it is also where the PRO line fits its own. A flexible pipe connects its barbed outlet to the top-up reservoir, placed higher than the target level. Gravity is enough to make the water flow, so no pump is needed in this setup.

🐟 A circuit fed by fish

In aquaponics, the valve tops up the water in a fish tank, whose pH and conductivity are set first of all for the fish and the nitrifying bacteria. It does not act on either of these parameters: it simply compensates, as it goes, for the volume lost to evaporation. Fitted in the sump, with a rainwater collector placed higher up, it handles the top-up on its own and keeps the submersible pump covered while you are away, within the limit of the stored volume.

🪴 On a tank or a sump

Outside the RDWC kit, the valve also holds the level of a rigid tank or a sump, provided that its float rests on the surface of the water and that the top-up container is placed higher. The level maintained corresponds to the height at which the float closes the valve, so you adjust it by the position of the valve in the tank. At the first fill, the water should flow freely and then stop by itself; if it keeps flowing, the arm is rubbing or the float is stuck. With a nutrient solution, which you prepare directly in the container, rinse the valve at every drain, because salts deposited under the valve eventually cause a slow leak.

Technical specifications

The essentials

Principle: Mechanical float valveThe float opens the inlet by dropping and closes it again by rising.
Feed: None – no mains, no batteriesA power cut won't stop it.
Space on an RDWC kit: In the controller pot
Water inlet: By gravity, from a containerThe tank sits above the level you want to maintain.
Fitting: Barbed, 16 mm
Float position: At the surface of the solutionThe level maintained is the one at which the float closes the valve.

To budget for separately

Container outlet: Fitting with 32 x 16 mm valve
Top-up reservoir: A sealed container, placed up high, and a flexible pipe

In the box

1 float valve, float pre-assembled

Valve function, fitting with 32 x 16 mm valve and PRO kit contents taken from the manufacturer's data sheets and manuals, on 08/10/2026.

Manufacturer and product safety

Manufacturer: Growrilla di Milone Giulio
Postal address: Via Fiano 207, 10070 Robassomero (TO), Italie
Contact: info@growrillahydroponics.com
Website: growrillahydroponics.com

Information provided under Regulation (EU) 2023/988 on general product safety.

Estimate your
delivery time

It is a small part, dispatched as a simple parcel or added to a larger order. Orders are shipped from the workshop in Robassomero, near Turin. 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 remain the responsibility of the recipient.

Frequently asked questions

6 questions

6 key questions

Where does it go on an RDWC kit?

At what height should the container be placed?

What happens during a power cut?

Does it correct the fertiliser and the pH?

Which kits does it fit?

Can the float become stuck?

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Float valve for automatic top-up

The summary