Dennerle CO2 Diffusor Ultra, Medium

Ceramic Disc CO2 Diffuser for Planted Tanks Up to 200 Liters

The Dennerle CO2 Diffusor Ultra (200L) is a freshwater planted tank CO2 diffuser rated for tanks up to 200 liters (~53 gallons). It is the mid-size in the Dennerle CO2 Diffusor Ultra range, sized for small- to mid-size planted setups that make up the largest segment of the active planted tank hobby — tanks in the 30- to 55-gallon range running a pressurized CO2 system with a regulator and solenoid on a photoperiod timer.

The ceramic disc atomization produces fine CO2 bubbles that maximize dissolution time before the bubbles reach the surface and escape the water column. Finer bubbles mean more CO2 absorbed per unit of gas delivered — a meaningful efficiency advantage in tanks where CO2 waste adds up over months of daily injection. The shatterproof acrylic body eliminates the fragility risk of glass diffusers, which are the most commonly broken component in a CO2 system. The built-in bubble counter integrates the monitoring function directly into the diffuser body, removing the need for a separate inline counter and simplifying the CO2 line between the regulator and diffuser.

Key Features:

• Ceramic disc CO2 diffuser rated for freshwater planted tanks up to 200 liters (~53 gallons)
• Ceramic disc produces fine CO2 bubbles for efficient dissolution and reduced gas waste
• Shatterproof acrylic body; more durable than glass diffusers
• Built-in bubble counter for convenient monitoring of CO2 bubble rate
• Includes CO2 hose with 4mm inner diameter / 6mm outer diameter
• Compact, clean design suitable for aquascape setups and display tanks
• Requires a separate CO2 source: pressurized cylinder with regulator, or BIO CO2 system

Ideal For:

• Small to mid-size planted tanks of 30 to 55 gallons running a pressurized CO2 system with a regulator, solenoid, and photoperiod timer as the standard daily CO2 delivery method
• Established planted tank hobbyists upgrading from a basic or lower-quality diffuser who want the fine atomization of a ceramic disc and the convenience of a built-in bubble counter in one unit
• Pet stores stocking the CO2 Diffusor Ultra in the mid-size configuration alongside CO2 regulators and complete systems in their freshwater planted tank section

Pro Tips:

• Use the built-in bubble counter in combination with a CO2 drop checker, not instead of one. The bubble counter tells you how much CO2 is entering the diffuser; the drop checker tells you how much is actually dissolving into the water. Both readings together give you a complete picture of CO2 delivery and uptake in the tank.
• Reduce CO2 injection at the end of the photoperiod or use a solenoid timer. Plants consume CO2 during the light period and produce it at night. Running CO2 injection after lights-out drives pH down unnecessarily and can stress fish. A solenoid on a timer that mirrors the photoperiod is the standard practice for any pressurized CO2 setup feeding this diffuser.
• Run the diffuser during a 100% water change to saturate the new water quickly. Fresh water added during water changes has lower dissolved CO2 than the tank water it replaces. Running the diffuser for 30 minutes after a water change helps restore CO2 levels to the target range before plant activity resumes.