CO2 injection is the single biggest upgrade you can make to a planted aquarium. Plants grow faster, colour up better and outcompete algae.
What is in a CO2 kit?
- Cylinder – holds pressurised CO2. Steel and aluminium are both common.
- Regulator – reduces cylinder pressure to a safe working level; a solenoid lets you switch CO2 off at night with a timer.
- Bubble counter – lets you see and fine-tune the injection rate.
- Diffuser – breaks CO2 into fine bubbles so it dissolves in the water.
Start slow
Begin with about one bubble per second for a 60–90 litre tank and increase gradually. Use a drop checker: green is the target, yellow means too much.
Safety first
Always run CO2 only during the lighting period and keep good surface agitation so fish have plenty of oxygen.
