Check Valve

A check valve is a small, inexpensive one-way valve installed in airline or CO2 tubing. Its sole purpose is to prevent water from flowing backwards through the tubing and into your air pump, CO2 regulator, or other equipment. Despite its tiny size, a check valve can prevent catastrophic equipment damage and flooding.

Why You Need a Check Valve

Back-Siphon Prevention

When an air pump or CO2 system shuts off (either intentionally via a timer, or accidentally during a power outage), gravity can cause water to travel backwards through the tubing. This water can:

• Flood your air pump, destroying the diaphragm and motor.
• Damage your CO2 regulator, corroding internal components.
• Drain your tank, potentially onto the floor or into electrical equipment.

A check valve blocks this reverse flow entirely.

Placement

The check valve should be installed as close to the water line as possible — ideally within 15cm of where the tubing enters the tank. This minimises the amount of water that sits in the tubing above the valve.

• Correct: Pump → tubing → check valve (near tank) → device in water
• Incorrect: Pump → check valve (near pump) → long tubing → device in water

Types of Check Valves

| Material | Durability | CO2 Resistant | Price | |---|---|---|---| | Plastic (Standard) | 6–12 months | No | $1–3 | | Brass | 2–5 years | Yes | $5–10 | | Stainless Steel | 5+ years | Yes | $8–15 |

CO2-Specific Check Valves

Standard plastic check valves degrade when exposed to pressurised CO2. The gas permeates the internal rubber seal, causing it to swell, crack, and eventually fail. For CO2 systems, always use a brass or stainless steel check valve rated for CO2 use.

Maintenance

• Test regularly: Blow through the valve to confirm it blocks airflow in the reverse direction.
• Replace annually: Plastic check valves should be replaced every 6–12 months as the internal seal wears.
• Clean debris: Algae, biofilm, and mineral deposits can clog the valve over time. Soak in vinegar or replace.

Trusted Brands

• Fluval: Reliable plastic check valves widely available.
• JARDLI: Stainless steel, CO2-rated, premium quality.
• Rhinox: Brass CO2 check valves with excellent sealing.
• Generic brass valves: Widely available on Amazon, very effective.

Pros & Cons

Advantages

• Equipment protection: Prevents water damage to pumps and regulators.
• Cheap insurance: Costs $1–10 to prevent potentially hundreds in damage.
• Simple installation: Just cut the tubing and insert inline.
• Peace of mind: Protection during power outages and timer shutoffs.

Considerations

• Flow restriction: Slightly reduces airflow; ensure your pump has adequate pressure.
• Failure risk: All check valves can fail — test periodically.
• CO2 compatibility: Not all check valves are rated for CO2. Use brass or stainless for pressurised systems.
• Replacement: Consumable item; budget for periodic replacement.