What Is CO2 Injection?
Aquatic plants need carbon dioxide to photosynthesize, and in a densely planted tank the CO2 naturally available in water is usually the limiting factor on growth — injecting CO2 from a pressurized cylinder through a diffuser removes that bottleneck and is what separates a “high-tech” planted tank from a low-light, no-CO2 setup.
Why Bubble Count Matters
Bubble count — literally counting bubbles per second passing through a bubble counter — is the traditional way to dial in a CO2 system, but it’s an indirect proxy at best, since bubble size and diffuser efficiency both affect how much CO2 actually dissolves. Most planted-tank keepers cross-check bubble count against a drop checker (which shows dissolved CO2 by color) and watch fish behavior closely, since too much CO2 is genuinely dangerous — fish gasping at the surface is a sign to cut injection immediately, not push through.
Shop CO2 Equipment
See CO2 Diffusers and Planted Aquarium CO2 Kit for full injection setups.
