Description
GLA PRO-CO2 Atomizing Reactor 5L
Advanced Atomizing CO2 Reactor for Nature Aquariums
The GLA PRO-CO2 Atomizing Reactor 5L combines high-pressure CO2 atomization with reactor-based dissolution to improve CO2 absorption while reducing gas accumulation.
Unlike traditional reactors that rely primarily on contact time and large gas chambers, the PRO-CO2 Reactor utilizes a removable ceramic atomizer to convert CO2 into an ultra-fine mist before it enters the reactor chamber. This dramatically increases gas-to-water contact area, helping CO2 dissolve more rapidly and efficiently than conventional large-bubble reactor designs.
The result is improved CO2 utilization, reduced gas accumulation, and more consistent CO2 delivery throughout the aquarium.
Hybrid Atomizing Reactor Technology
The PRO-CO2 Reactor uses a two-stage dissolution process:
- Stage 1: High-pressure atomization creates thousands of microscopic CO2 bubbles.
- Stage 2: The reactor chamber provides additional contact time for efficient dissolution.
Rather than relying solely on contact time, this hybrid design combines atomization and reactor-based dissolution to help maximize the amount of injected CO2 that enters solution before water returns to the aquarium.
- Faster CO2 dissolution
- Improved CO2 utilization
- Reduced gas accumulation and pocketing
- More stable dissolved CO2 concentrations
- Cleaner aquarium presentation with no visible in-tank diffuser
Improved CO2 Utilization
The GLA PRO-CO2 Reactor is designed to help maximize the effectiveness of every bubble of CO2 introduced into the system.
By atomizing CO2 before it enters the reactor chamber, the system increases gas-to-water contact area and improves overall absorption efficiency.
Many aquarists can achieve target CO2 levels while operating at lower bubble rates than conventional large-bubble reactor designs. Actual results will vary depending on aquarium size, filtration flow, circulation, plant mass, and CO2 demand.
- Reduced CO2 waste
- Potentially lower operating bubble rates
- Reduced gas accumulation within the reactor
- More stable CO2 levels
- Longer intervals between CO2 cylinder refills
By improving overall CO2 utilization, the reactor helps make more efficient use of every CO2 cylinder refill.
High-Pressure Ceramic Atomizing Core
At the heart of the reactor is a removable high-pressure ceramic atomizer that produces an ultra-fine CO2 mist for rapid dissolution and improved reactor efficiency.
- Increased gas-to-water contact area
- Faster CO2 absorption
- Reduced gas pocketing
- Improved performance across a wide range of flow rates
- Removable for cleaning and servicing
Oversized Internal Flow Path
The latest PRO-CO2 Reactor features an enlarged internal standpipe and expanded flow path designed to reduce restriction and improve water movement through the reactor.
- Larger internal standpipe
- Larger flow passages
- Reduced hydraulic restriction
- Improved flow capacity
- Enhanced compatibility with larger filtration systems
These improvements allow greater water throughput while maintaining excellent CO2 dissolution performance.
Expanded Filter Compatibility
The reactor includes adapter sets for 12mm, 16mm, 20mm, and 1" tubing, making it suitable for a wide range of canister filters, external pumps, compact planted aquariums, and larger high-flow systems.
- 12mm Adapter Set Included
- 16mm Adapter Set Included
- 20mm Adapter Set Included
- 1" Adapter Set Included
- Compatible with many Fluval FX Series installations
Each adapter connection utilizes a clear silicone O-ring to provide a water-tight seal between the adapter and reactor lid.
High Flow Capability
The PRO-CO2 Reactor is engineered to operate across a wide range of flow rates and is particularly well suited for larger planted aquariums, high-energy aquascapes, and high-flow filtration systems.
- Minimum Recommended Flow: Approximately 300 GPH
- Typical Operating Range: 400–1200 GPH+
- Suitable for many canister filters and return pumps
- No additional power required; operates using existing filtration flow
Push-Connect CO2 System
The reactor utilizes a push-connect CO2 fitting and removable atomizer assembly for quick installation and simple servicing.
- Tool-free CO2 tubing installation
- Easy atomizer removal
- Simplified maintenance
- Long-term serviceability
Serviceable Atomizer Design
Unlike permanently integrated systems, the PRO-CO2 Atomizing Reactor uses a removable ceramic atomizer assembly.
- Removable for cleaning and maintenance
- Replaceable if needed
- No need to replace the entire reactor for atomizer maintenance
Maintenance-Friendly Construction
The large reactor body and removable top allow easier inspection, access, and routine maintenance. The clear chamber also makes it easier to observe reactor operation during setup and troubleshooting.
Why Choose a CO2 Reactor?
Many aquarium CO2 systems lose efficiency when undissolved gas accumulates within equipment or returns to the aquarium before fully dissolving.
The GLA PRO-CO2 Reactor is engineered to maximize CO2 absorption before water returns to the aquarium, helping provide:
- Stable CO2 levels
- Improved plant growth potential
- Reduced CO2 consumption
- Cleaner aquarium presentation
- No visible in-tank diffuser
- Reduced visible microbubbles in the aquarium
- No additional power required
Specifications
- Reactor Chamber Capacity: 5 Liters
- Height: Approximately 20"
- Diameter: Approximately 6"
- Minimum Recommended Flow: Approximately 300 GPH
- Typical Operating Range: 400–1200 GPH+
- Installation Location: Filter return line
- CO2 Connection: Push-connect fitting
- Included Adapter Sizes: 12mm, 16mm, 20mm, and 1"
- Construction: Acrylic
What’s Included
- GLA PRO-CO2 Atomizing Reactor 5L with Installed High-Pressure Ceramic Atomizer
- 12mm Adapter Set
- 16mm Adapter Set
- 20mm Adapter Set
- 1" Adapter Set
- Clear Silicone O-Rings
- Installation & Maintenance Guide
Feature Highlights
- Hybrid Atomizing Reactor Technology: Combines high-pressure atomization with reactor-based dissolution.
- Improved CO2 Utilization: Helps reduce CO2 waste and may allow lower operating bubble rates.
- Reduced Gas Pocketing: Designed to minimize gas accumulation inside the reactor chamber.
- Removable Ceramic Atomizer: Serviceable atomizer core for easier cleaning and maintenance.
- Push-Connect CO2 Installation: CO2 tubing and atomizer assembly push in easily for simple setup and servicing.
- Oversized Internal Flow Path: Helps reduce restriction while supporting strong water movement.
- Expanded Filter Compatibility: Includes 12mm, 16mm, 20mm, and 1" adapter sets.
- Fluval FX Series Compatible: Designed to support many high-flow Fluval FX filter installations.
- External Installation: Keeps the aquarium clean with no visible in-tank diffuser.
- No Additional Power Required: Operates using existing filtration flow.
Frequently Asked Questions
How is this different from a traditional CO2 reactor?
Traditional CO2 reactors primarily rely on contact time to dissolve larger CO2 bubbles. The GLA PRO-CO2 Atomizing Reactor first atomizes CO2 into an ultra-fine mist before introducing it into the reactor chamber. This increases gas-to-water contact area and improves overall dissolution efficiency.
Will this reactor reduce CO2 consumption?
Many aquarists find they can achieve target CO2 levels while operating at lower bubble rates compared to conventional large-bubble reactor designs. Actual results will vary depending on aquarium size, flow rate, plant mass, circulation, and CO2 setup.
Does the reactor eliminate gas pocketing?
The atomizing core is designed to significantly reduce the gas accumulation commonly associated with traditional reactor designs. Small amounts of gas accumulation may still occur depending on flow rate, CO2 injection level, and system configuration.
Is the ceramic atomizer serviceable?
Yes. The ceramic atomizer assembly is removable for cleaning, maintenance, or replacement if needed.
What filter tubing sizes are included?
The reactor includes adapter sets for four installation sizes: 12mm, 16mm, 20mm, and 1" tubing.
Are silicone O-rings included?
Yes. Clear silicone O-rings are included for the adapter connections. Each O-ring should be properly seated beneath the adapter connection to help provide a water-tight seal between the adapter and reactor lid.
Is this compatible with Fluval FX Series filters?
Yes. The included 1" adapter set provides compatibility with many Fluval FX Series filter installations.
Where should the reactor be installed?
The reactor should be installed externally on the filter return line after the canister filter and before water returns to the aquarium.
Correct installation:
Canister Filter → PRO-CO2 Reactor → Aquarium Return
Do not install the reactor on the filter intake line.
Will I still need an in-tank diffuser?
No. The reactor is installed externally and is designed to dissolve CO2 before water returns to the aquarium, helping maintain a clean display without a visible in-tank diffuser.
Does the reactor require additional power?
No. The reactor operates using existing filtration flow and does not require a separate pump or power source.
Can the atomizer be removed for cleaning?
Yes. The atomizer assembly can be removed for routine cleaning and servicing.
Do I need any tools to tighten the reactor lid screws?
No. The reactor lid screws are designed to be tightened by hand only. Do not use screwdrivers, drills, power tools, pliers, or excessive force when tightening the lid screws.
Over-tightening may damage screws, threads, seals, O-rings, or acrylic components. Tighten the screws using moderate hand pressure only.
Is a check valve included?
A check valve is recommended between the regulator and reactor to help prevent water backflow into the CO2 system. Check valve sold separately and not included with the reactor.
Improved CO2 Utilization. Reduced Gas Accumulation. Professional-Grade Performance.
Customer Reviews
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Whatever co2 reactor you use, throw it away.
Yugang was a nightmare to deal with all the time and was wasteful with Co2. I hated how stupid huge it was taking up the length of the cabinet. Constant fiddling and adjusting and it just isn’t a system fit for everybody. This month I switched to GLA reactor and the difference is incredible. While it may be a tall unit, it doesn’t take up so much space lengthwise. It also doesn’t require any messing with or constant adjusting of the co2 system. I set it up and it worked instantly. My ppm of 40/45ppn is steady all day confirmed by my co2 test kit and GLA new 4DKH solution. I like that there is no gas pocket at any point of the day. Co2 dissolving quickly which is just astounding. The atomizer I noticed is removable so I like that and I’m waiting for GLA to provide the atomizers as a separate purchase so I can swap between cleanings. The atomizers itself creates a super fine mist where the bubble is so small it dissolves in 2-3 seconds. The surface area is immense so your levels of co2 are rock solid so I advise to go slow as I almost gassed my tank, so my advice is to start slow on co2. I made that mistake because I forgot to adjust my co2 from previous reactor. Otherwise absolutely awesome reactor. But please, GLA provide us with the option to buy an extra atomizer as we could really use them. ?
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This is the best reactor.
I own several reactor types over the years and this one is by far the very best I’ve ever used. It waste no co2 and is always full of water. No bubble inside at all even at the end of the photoperiod. There is truly nothing else like it anywhere. Just know the unit is quite large so confirm you have space. GLA is always providing game changing CO2 equipment and I’ve been a customer for a few decades now. High quality from top to bottom and includes all these extra fittings for various tube sizes.
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Total game changing CO2 reactor.
Coming from my first Cerges reactor to then the nightmare Yugang reactor and back to a Cerges. I ended the nightmare by giving the GLA reactor a shot. First thing I noticed is its massive size, an absolute monster of a reactor. Literally I set it up and off the start it just started working like you would want a reactor to perform. In 55 minutes or less my ph was down 1.2 points and a lime green drop checker after my first hour. At 3hrs was near gassing my fish so I had to make some adjustments to surface agitation. I made no adjustments to co2 into the reactor. Now it’s absolutely perfect. I feed co2 9hrs of the day. No big gas bubble, no sounds. And most of all no waste of CO2 like that dang nightmare Yugang reactor which was a total abortion. If you are looking to go with a CO2 reactor this is the only one you get. GLA killed it with that huge atomizer in the reactor. Love it!
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Took the plunge on this and what a game changer.
This thing is quite large and very high quality. The diffusion and saturation of CO2 is phenomenal. Totally worth the investment GLA has knocked it out of the park once again. I absolutely love this reactor. Comes with every size tubing connector imaginable and the diffuser is easily removable. Best reactor you’ll find is this. I had the Yugang style reactor and what a total abomination and waste of money and CO2. I don’t know why people think a reactor burping huge bubbles of co2 is ideal lol what a total junk concept. Buy this instead safe the hassle.
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Where has this been all my years in aquascaping.
19 years aquascaping where I’ve used reactors and diffusers of so many types. My previous reactor was a Yugang reactor which was at first I thought I good system. Bloody hell that was a disaster. It waste so much CO2 and it does it by design which to me is insane. So I went back to GLA diffusers like I’ve always used because they always have the best diffusers. They work so well in fact it creates an absolute fog mist of CO2. I grow tired of the constant fog so I decided to try this new reactor from GLA. People, when I say this thing is the best I don’t say that lightly, it works tremendously well and doesn’t waste a drop of CO2. GLA deserves an award for constantly bringing the newest and best innovations to planted tanks. From the CO2 regulator they invented to the high pressure atomizers and now this animal. It’s an absolute beast of working functional co2 delivery I can count on day after day. Thank you GLA Team for answering all my questions and supporting the hobby that brings me much joy.
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The Rolls-Royce of aquarium CO₂ reactors
The CO₂ Reactor is the Rolls-Royce of aquarium reactors. From the moment you open the box, it's clear this is a premium, expertly engineered product. The craftsmanship is outstanding, and every component feels solid and built to last. Just as impressive as the reactor itself is the company behind it. Their customer support is exceptional—they genuinely care about their customers and stand behind their products. That level of service is becoming rare these days. While it costs more than many other reactors, you truly get what you pay for. If you want a high-quality CO₂ reactor that performs flawlessly and is built to last, this is the one. It's worth every penny and is the real deal.
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Gla pro
Great reactor
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Serious piece of kit
This thing is fantastic. So well built and it feels like it will last forever. Running in an 88g Fluval Siena and no more bubbles. Not the least expensive option to be sure, but worth every penny IMO. Just make sure you have a filter with some power and you won't be disappointed at all. Well done GLA!
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No question this is the best CO2 diffusion ⭐️⭐️⭐️⭐️⭐️system on earth.
My second reactor so I have good experience using reactors. First, be smart, start your bubble rate slow because this baby works so well your fish and equipment will start pearling. Not just plants, but the hardscape, glass pipes and anything else in the tank. I was very close to gassing my fish at my usual bubble rate, luckily I noticed and dropped my bubble rate down to half. This thing is absolutely brilliant, it works incredibly well so I advise you start slow and watch your drop checker. The atomizer inside is unreal, it pulverizes co2 into a very fine atomized mist like no other diffuser I’ve seen. I have a feeling I’m going to finally start saving lots of co2. Kudos to the team at GLA for bringing yet another pioneering CO2 device to the hobby. You guys are do a couple of rewards for this CO2 reactor and modular manifold system. ⭐️⭐️⭐️⭐️⭐️
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CO2 Reactor and Support
I was a complete newbie at this and their texting support was just friggin AMAZING at helping me set it up and even provided reference images! It works fantastically and I've had ZERO issues!
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Without doubt the best co2 reactor in the game.
This is a huge reactor so be sure to read the specs. I suggest adding 2” to what they list due to the hose connections. It’s a large volume unit where zero co2 escapes, zero waste! My tank is on point daily with co2. Plants pearling and my plumbing looks rad!
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Best co2 reactor on the market.
I’m not novice to using co2 reactors as I’ve got a few I’ve used. This GLA reactor is near perfect. I’d rate it 5 stars if it came with a check valve for the co2 tubing. Other than that it’s perfect. Very well made design without a drop of co2 escaping. I have mine hooked up to a dedicated pump made by Iwaki and it moves water like a beast at 1800gph. Reactor performs perfectly everyday.
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Absolute CO2 excellence.
I own quite a bit of equipment from GLA and every time it’s top quality stuff. Their service is also unmatched. I’m louding service because they have an incredible text message service. They provide photos and videos of whatever you might need. Really great people to work with. But back to this reactor, it’s a really good reactor. Comes with a bunch of hose fittings to choose from and they even include a whole dang roll of Teflon tape lol. It took me about two days to dial in to perfection. Tank is crystal clear and void of the 7-Up look from traditional diffusers. Now the only visible bubbles are my plants peeling like mad.
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Outstanding reactor and premium customer service.
The reactir is absolutely outstanding and GLA’s customer service is amazing. They should write a book on how to setup and install co2 systems on very large tanks. My tank is 230g in size and they helped me from start to finish and I could not be more pleased. Everything was shipped for free. The service was free and worth every penny in my investment in a full GLA CO2 system. Everything works like a top. Thank you GLA.
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It’s an absolute unit of a co2 reactor.
You really don’t get the size of how big it is until it arrives, it’s huge! Pro tip: I installed the GLA inline at the top to atomize co2 prior to it entering the reactor and it works INCREDIBLY well. Then! I used the original co2 inlet port for my GLA Nectar AIO Dosing port. Injecting fertilizer into a virtual mixing vessel prior to entering the tank. This was GLA’s advice and I could not be happier. What a work of art this system has turned out to be.
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GLA is the best in aquascaping gear.
Been a customer with GLA since 2008. Still using my old co2 kit from then and now upgraded to this co2 reactor. It’s been an amazing unit and works really well on my 120g tank. It’s a huge reactor so it’s been able to handle the high flow from my pump and large amount of co2. Thanks GLA for continuing to put out great products.
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Very pleased with this co2 reactor.
Super efficient and high quality reactor. Using this on my 90g has been an absolute success. Plants are happy and my drop checker is a perfect shade of green/yellow. Yes I keep my co2 on the high side but my tank is happy!
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Beast mode has been activated!
The photo does no justice with this reactor. It’s massive and works perfectly! Co2 levels are stable and stay steady everyday. I have my co2 on a ph controller so my levels are dialed into perfection. High quality unit that freaking works! A++
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This thing rocks!
This is what I’ve wanted since ditching my Cerges reactor. That thing was a nightmare and an absolute abortion of a design. With this it’s just super easy to use and I don’t ever mess with it. My co2 is stable and always puts my drop checker near the yellow zone in short time.
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GLA the best in co2 equipment.
I use GLA equipment for years and never a problem. GLA customer support always very kind and supportive anytime I have a question on anything. Really love their text-message support system which was just incredible at my success with my aquascape. This will be my 2nd time entering IAPLC contest and already feeling positive. Love this reactor.
