An air lock is a pocket of trapped air sitting inside your irrigation pipework. It acts like an invisible plug — stopping water dead even though everything looks fine from the outside. Left unchecked: uneven feeding, stressed plants, and a root zone that never quite gets what it needs.
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The frustrating part? Air locks mimic blockages perfectly. Growers replace emitters, flush lines, and strip fittings looking for a clog that isn't there — while the real problem sits invisibly in the pipe.
The Root Cause
Six Reasons Air
Gets Into Your Lines
01
Low Reservoir Level When the tank drops too low, your pump starts drawing air alongside water. That air has to go somewhere.
02
Up-and-Over Pipe Runs Lines that go over the lip of a tank or up-and-back collect air at the highest point. Classic grow room issue.
03
Micro-Leaks on Suction Side Tiny gaps in fittings admit air under suction. You won't see them — but the pump finds them every time.
04
Drain-Down Between Cycles If laterals empty between feeds, refilling traps air pockets as water pushes back through the line.
05
Rapid Pressure Changes Hard starts, fast stops, or quick valve closures can pull air into the line before pressure stabilises.
06
Poor Priming on Setup If you don't bleed the lines when you first build, air gets locked in from day one — and never leaves.
The Fix
Right Component.
Right Place. Every Time.
Air locks are very fixable — and with the right components in the right positions, preventable entirely. Here's what solves each part of the problem:
| Problem |
Solution |
| Trapped air and salt build-up in lines |
FloraFlex Flush Valve — one twist purges trapped air, salts, and debris. Install at the low point or end of line for fast bleeding and routine maintenance. |
| Lines draining and siphoning between feeds |
Netafim DNL Valve — holds the line closed until opening pressure is reached. Prevents drain-down and stops air being pulled back in between cycles. |
| Elevated tank or attic reservoir setup |
Anti-Siphon Valve — breaks the gravity siphon when the pump shuts off. Stops unintended flow and air being pulled back through the line. |
| Leaky connections admitting air |
Quick-Fit Hose Connectors and Tap Connectors — leak-free fittings that remove the entry points air exploits on the suction side. |
Common Question
DNL vs Anti-Siphon —
What's the Difference?
These two overlap, and that's where the confusion comes from. They're solving different parts of the same problem:
A Netafim DNL is an anti-drain / anti-backflow check valve. It keeps the line primed, prevents flow reversal, and won't open until the pump builds enough pressure. Think of it as a one-way door that stays shut between cycles.
An anti-siphon valve is designed specifically to break a siphon path — critical when there's a height difference between your reservoir and your emitters. It stops water continuing to run after the pump shuts off, and stops air being pulled back through once the line empties.
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Attic tank setup? Gravity will create a siphon after the pump shuts off — even with pressure-compensated drippers. An anti-siphon valve near the riser breaks it before it empties your laterals and pulls air back through.
Get the Order Right
Where Everything
Goes in Your System
The components matter — but so does where you put them. Getting the layout wrong means protection in the wrong place, or none at all.
01
Pump → Filter Always upstream of your valves and emitters — right after the pump or water source. Protects everything downstream from particulates that cause real blockages.
02
Filter → Anti-Siphon Valve At the high point or riser — wherever a siphon could form due to elevation. Breaks the gravity path when the pump stops.
03
Anti-Siphon → Manifold → DNL The
DNL goes downstream to enforce one-way flow and keep lines primed between feed cycles.
04
End of Line → Flush Valve Low point or end-of-run. Makes bleeding and salt removal a 10-second job rather than a full strip-down. Use it regularly.
Starting Fresh?
Build It Right
From Day One.
If you're setting up a new system or rebuilding, the Complete Whip Kit gives you a neat, consistent feed line to every site from the start. Pair it with a flush valve, the right DNL, and an anti-siphon valve where needed — and you've got a pro-level, low-maintenance setup that won't let you down mid-cycle.
Stop Chasing
Phantom Clogs.
Sort the root cause. Keep the lines flowing.
FAQ
Frequently Asked
Questions
What is an anti-siphon valve?
A device that breaks a siphon path in your irrigation line — preventing water from continuing to flow (or pulling air back through) after the pump shuts off. Essential in any setup where the tank sits higher than the emitters.
Do I need an anti-siphon valve for hydroponics?
If your reservoir or header tank is elevated above your drippers, yes. It stops unintended post-pump flow and prevents air from being sucked back into the line when it empties. For level setups, a
DNL is still worth adding to keep lines primed between feeds.
How do I install an anti-siphon valve?
Most fit standard irrigation lines with clear instructions included. Install at the highest point in the run or near the riser — wherever a siphon is most likely to form.
Drop us a message if you want advice for your specific setup.
Are these valves compatible with automated irrigation systems?
Yes — they work with timers, drip systems, and any automated setup. Just make sure the valve sits in the correct position in the run, not just anywhere in the line.
What are your valves made from?
We stock valves in corrosion-resistant plastics and brass, chosen for long-term performance in indoor and outdoor growing environments.
