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LIGHTING & CO₂

CO₂ Regulator

Dual-gauge regulator with solenoid, needle valve and bubble counter for injected carbon.

Planting stage Lighting
Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking
LightingTechnical line drawing of CO₂ Regulator
Specification
Cylinder pressure800–1000 psi
Working pressure1–3 bar
GaugesHigh pressure + low pressure
ValveSolenoid, 12 V or mains
Fine controlPrecision needle valve
FittingsDIN 477 or US CGA-320
Technical parameters
Target CO₂~30 ppm
Safe upper limit30 ppm — above this fish gasp
On before lights1–2 hours
Off before lights1–2 hours
Cylinder life, 2 kg2–4 months at 1 bubble/s
Bubble rate, 60 cm tank1–2 bubbles/second

A CO₂ regulator steps the 800–1000 psi in a pressurised cylinder down to the 1–3 bar that a diffuser can use, and lets you meter the flow finely enough to hit a target of about 30 ppm dissolved CO₂.

The features that separate a good regulator from a frustrating one are a two-stage or dual-gauge design, a solenoid valve, and a precision needle valve. The high-pressure gauge tells you when the cylinder is nearly empty; the low-pressure gauge tells you the working pressure; the solenoid lets a timer switch the gas off at night; the needle valve is what you actually adjust, and a cheap one will drift and change your bubble rate overnight.

CO₂ is switched on 1–2 hours before the lights and off 1–2 hours before they go off. Plants only consume carbon while photosynthesising, so running it at night wastes gas and drives pH down when nothing is using it. A drop checker at the far end of the tank is the measurement that confirms the injection rate is right.

Safety and welfare
  • A pressurised CO₂ cylinder is a pressure vessel. Secure it upright with a strap — a falling cylinder can shear the valve off and turn into a projectile.
  • Never exceed 30 ppm dissolved CO₂. Fish and shrimp suffocate before any visible warning. Watch for gasping at the surface as an emergency signal.
  • Ventilate the room if you smell or suspect a leak, and check the cylinder-to-regulator seal with soapy water, never a flame.

Using it well

Set the bubble rate, wait two hours, then read the drop checker. Adjust once, not continuously.
A solenoid that buzzes is usually under-volted or the coil is failing. Replace it before it sticks open.
Keep a spare cylinder. Running out mid-week drops CO₂ to zero, plants stall and algae take the gap.

Complete system needs

CO₂ cylinderRegulator with solenoidBubble counterCO₂ diffuserDrop checkerTimer
Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.
Related

Works alongside

CO₂ DiffuserLightingBubble CounterLightingDrop CheckerLightingLighting TimerLighting