Product Information

ISTA CO₂ External Reactor I-539  Maximise CO₂ Absorption, Compact External Design and Professional Aquascaping Performance

Take your planted aquarium to the next level with the ISTA CO₂ External Reactor I-539, a precision-engineered CO₂ dissolution system designed to ensure maximum carbon absorption before water re-enters your tank. Unlike regular diffusers, this external reactor uses a patented impeller system to crush and dissolve CO₂ bubbles effectively, reducing gas waste and improving plant health.

With its compact design and easy installation on the return line of your canister filter, this unit keeps your aquarium neat while boosting the effectiveness of your CO₂ injection setup — perfect for serious planted tank enthusiasts and aquascapers.

Key Benefits

• Maximum CO₂ Dissolution Efficiency: Patented impeller design continually breaks down CO₂ bubbles, ensuring they stay dissolved in the water rather than escaping at the surface.

• Healthy Plant Growth: Higher CO₂ concentrations in water support stronger photosynthesis and lush plant development.

• External Installation: Mounts neatly on the canister/external filter return line, keeping aquarium interiors clean and unobstructed.

• Transparent Chamber: See the flow and mixing process at a glance — no guesswork.

• Durable & Low Maintenance: Designed from acid-resistant materials and simple to clean or service as needed.

Product Features

• Model: ISTA CO₂ External Reactor I-539

• Installation: Inline external with canister filter return line

• Compatibility: Fits standard 12/16 mm (13 mm) hose pipes.Not suitable for 17mm hose, you may need to add reducer on both side to use with 17mm hose models

• Efficient CO₂ Mixing: Uses water flow to crush and dissolve gas — no additional power needed.

• Easy Assembly: Modular design allows quick cleaning and ceramic tube replacement.

• Compact & Space-Saving: Ideal for medium to large planted aquariums needing advanced CO₂ diffusion.

Why You Need an External CO₂ Reactor

Standard ceramic diffusers can waste CO₂ — bubbles often reach the surface and escape into the air before dissolving. The ISTA External Reactor solves this by keeping CO₂ in contact with moving water longer, ensuring almost all injected gas dissolves into your aquarium water for plant use.

This means:

• Less gas wasted

• More stable CO₂ levels

• Better plant health

• Reduced nutrient imbalances

Ideal For

• Pressurised CO₂ systems

• High-tech aquascapes

• Canister or external filter setups

• Medium to large planted aquariums

• Aquarists seeking efficient CO₂ utilisation

Pro Tips for Best Results

• Install on the return hose of your canister/external filter to ensure optimal water flow through the reactor.
• Use CO₂-rated flexible tubing and secure connections to prevent leaks.
• Periodically rinse with aquarium water to maintain dissolution efficiency.

The ISTA CO₂ External Reactor I-539 is a must-have for hobbyists who want professional CO₂ dispersion without visual bubbles in the display tank and maximum carbon utilisation for vibrant plant growth — making it one of the most effective CO₂ accessories for planted aquariums available today.