Ceramic Glass Diffuser
Traditional in-tank diffuser. Ceramic disc produces fine bubbles. Cheap and simple.
Pros: low cost, works for tanks up to 200L. Cons: visible in tank, bubbles don't always fully dissolve, needs cleaning monthly.
Inline Diffuser
Placed in canister return line. CO2 injected into outgoing water, dissolving fully before returning to tank.
Pros: no visible bubbles in tank, high efficiency. Cons: requires canister filter, slightly harder to install.
Reactor (DIY or Commercial)
External chamber where CO2 and water mix forcefully. Near 100% dissolution.
Pros: maximum efficiency, great for large tanks (500L+). Cons: complex install, occasional airlock issues.
Picking by Tank Size
Under 100L: ceramic diffuser is fine. 100-300L: inline diffuser preferred. 300L+: reactor or multiple inline diffusers.
Consider aesthetics — for show tanks, always hide CO2 equipment via inline or reactor.