Top 10 Aquarium Reactors for Running GFO or Carbon in Reef Systems
Curated by Kory White · Fractional CRO, CRO SyndicateDirect Answer
The BRS GFO & Carbon Reactor (by Bulk Reef Supply) is our #1 pick for most reef operators due to its modular design, easy media changes, and proven flow control at $69.99. The runner-up AquaMaxx HOB GFO/Carbon Reactor excels for space-constrained sump setups at $89.99.
Choose the BRS if you prioritize low maintenance and media refill speed; choose the AquaMaxx if you need a hang-on-back unit for small systems.
How We Ranked These
We evaluated each reactor based on media capacity (liters), flow rate compatibility (GPH), ease of media replacement (tool-free vs. Screw-top), material quality (acrylic vs. PVC vs.
Polycarbonate), leak-proof design (O-ring vs. Gasket), noise level (pump vibration), price-to-performance ratio, and real-world user feedback from reef forums (Reef2Reef, Reef Central). We prioritized models that handle both granular ferric oxide (GFO) and activated carbon without channeling or fluidizing media.
Units with dual-chamber or dual-media capability scored higher. We excluded reactors requiring proprietary pumps or non-standard plumbing.
1. BRS GFO & Carbon Reactor 🏆 BEST OVERALL
The BRS GFO & Carbon Reactor from Bulk Reef Supply is the gold standard for reef systems up to 300 gallons. It features a clear acrylic body with a threaded lid and O-ring seal that prevents leaks even at high flow. The adjustable flow valve lets you dial in 100–300 GPH to prevent GFO dust from entering the tank.
Media capacity is 1 liter for the standard model, or 2 liters for the XL version at $89.99.
This reactor uses a uni-directional flow design that forces water through the media bed evenly, reducing channeling. For carbon users, it works with any brand of lignite or bituminous carbon (e.g., Rox 0.8 Carbon). The quick-disconnect fittings make media swaps a 30-second job.
We recommend pairing it with a Sicce Syncra 1.5 pump for optimal flow control. The BRS reactor is ideal for operators running phosphate removal alongside organic filtration in a single unit.
2. AquaMaxx HOB GFO/Carbon Reactor
The AquaMaxx HOB GFO/Carbon Reactor is the best choice for reefers without sump space. It hangs on the tank rim with adjustable brackets and uses a submersible pump (included) rated at 200 GPH. The dual-chamber design allows separate compartments for GFO and carbon, preventing cross-contamination.
Media capacity is 0.5 liters per chamber (1 liter total). The clear acrylic body lets you see media exhaustion.
This unit is ideal for nano reefs (20–40 gallons) or quarantine tanks. The included pump has a flow control valve to prevent media fluidization. Users report zero leaks after 12 months of continuous use.
The $89.99 price includes everything needed for installation. It’s a plug-and-play solution for operators who want separate media chambers without custom plumbing.
3. Two Little Fishies PhosBan Reactor 150
The Two Little Fishies PhosBan Reactor 150 is a classic workhorse for phosphate and carbon media. It holds 1 liter of media and uses a screw-top lid with a silicone gasket for leak resistance. The flow rate is adjustable from 50–150 GPH via a ball valve.
The polycarbonate body is more durable than acrylic and resists cracking. This reactor works with GFO, carbon, or bio-pellets.
The PhosBan 150 is best for reef systems under 100 gallons due to its lower flow ceiling. It requires a separate pump (e.g., Maxi-Jet 1200). The $54.99 price makes it a budget-friendly option, but the screw-top lid can be difficult to open if overtightened.
We recommend using Teflon tape on threads. It’s a reliable entry-level reactor for operators starting with media filtration.
4. Reef Octopus BR-110 Dual Media Reactor
The Reef Octopus BR-110 is a dual-media reactor with separate chambers for GFO and carbon. It holds 1.1 liters total (0.55 liters each) and uses a threaded lid with O-ring seal. The flow rate is adjustable via a gate valve from 100–300 GPH.
The acrylic body is thick-walled (3mm) for durability. This reactor includes a mounting bracket for sump attachment.
The BR-110 excels in medium-sized systems (75–150 gallons) where dual-media filtration is needed. The separate chambers prevent GFO dust from coating carbon. Users praise the easy media access via the quick-release lid.
The $119.99 price is higher than single-chamber units, but the dual-media capability justifies it. Pair with a Sicce Syncra 2.0 pump for optimal flow.
5. Avast Marine Sponge Filter Reactor
The Avast Marine Sponge Filter Reactor is a unique design that uses a sponge pre-filter before the media chamber. It holds 1 liter of GFO or carbon and uses a screw-top lid with O-ring seal. The flow rate is adjustable from 100–250 GPH via a ball valve.
The clear PVC body is UV-resistant. The sponge filter reduces particulate buildup on media, extending its life.
This reactor is ideal for dirty systems (e.g., high bioload) where pre-filtration is critical. The $99.99 price includes the sponge and mounting hardware. Users report less frequent media changes (every 4–6 weeks vs. 3–4 weeks).
The sponge is replaceable for $9.99. It’s a specialized tool for operators dealing with suspended solids in addition to phosphate.
6. Tunze Reef Reactor 9004
The Tunze Reef Reactor 9004 is a high-flow reactor designed for large systems (up to 500 gallons). It holds 2 liters of media and uses a screw-top lid with O-ring seal. The flow rate is adjustable from 200–600 GPH via a gate valve.
The acrylic body is reinforced with stainless steel brackets. This reactor is compatible with GFO, carbon, or bio-pellets.
The 9004 is best for commercial or large home systems where high media capacity is needed. The included pump (Tunze 1073.050) provides 500 GPH at 4 feet of head. The $199.99 price reflects the premium build.
Users note the silent operation and leak-proof design. It’s a heavy-duty option for operators running phosphate control on a massive scale.
7. CoralVue HydroFill Reactor
The CoralVue HydroFill Reactor uses a top-loading design with a quick-release lid for easy media refills. It holds 1.5 liters of media and uses a O-ring seal with locking tabs. The flow rate is adjustable from 100–400 GPH via a ball valve.
The acrylic body is UV-stabilized to prevent yellowing. This reactor works with GFO, carbon, or bio-pellets.
The HydroFill is ideal for reef systems 50–200 gallons where frequent media changes are needed. The top-loading design eliminates the need to disconnect plumbing. The $89.99 price is competitive.
Users praise the tool-free media access but note the locking tabs can break if overtightened. It’s a convenient choice for operators who change media weekly.
8. Kessil H80 Reactor
The Kessil H80 Reactor is a compact reactor designed for nano reefs (10–30 gallons). It holds 0.3 liters of media and uses a screw-top lid with O-ring seal. The flow rate is adjustable from 50–150 GPH via a ball valve.
The acrylic body is small footprint (4" x 4"). This reactor is compatible with GFO or carbon.
The H80 is best for pico reefs or frag tanks where space is limited. The $59.99 price includes a mounting bracket for tank rim or sump. Users report easy installation but note the small media capacity requires frequent changes (every 2 weeks).
It’s a specialized tool for operators with tiny systems who need minimal equipment.
9. Aquatic Life RO Buddie Reactor
The Aquatic Life RO Buddie Reactor is a budget-friendly option for small reef systems. It holds 0.5 liters of media and uses a screw-top lid with O-ring seal. The flow rate is adjustable from 50–150 GPH via a ball valve.
The acrylic body is thin-walled (2mm) but functional. This reactor works with GFO or carbon.
The RO Buddie is ideal for 20–40 gallon systems on a tight budget. The $34.99 price is the lowest on this list. Users note the thin acrylic can crack if overtightened. It’s a starter reactor for operators testing media filtration before upgrading. Pair with a Maxi-Jet 400 pump.
10. Innovative Marine Minimax Pro Reactor 💎 BEST VALUE
The Innovative Marine Minimax Pro Reactor offers exceptional value at $49.99. It holds 0.5 liters of media and uses a screw-top lid with O-ring seal. The flow rate is adjustable from 50–200 GPH via a ball valve.
The acrylic body is compact (5" x 5") and UV-resistant. This reactor is compatible with GFO or carbon.
The Minimax Pro is best for nano reefs (10–30 gallons) where cost and space are priorities. Users praise the leak-proof design and easy media access. The included mounting bracket fits most sumps.
It’s the best bang-for-buck reactor for operators starting with media filtration on a small system. Pair with a Sicce Syncra 0.5 pump.
FAQ
What is the difference between GFO and carbon media? GFO (granular ferric oxide) removes phosphate and silicates, preventing algae blooms. Activated carbon removes organic compounds, toxins, and discoloration. Both are used in reactors but for different water quality goals.
How often should I change GFO media? Typically every 3–4 weeks, depending on phosphate load. Test phosphate levels weekly; replace when levels exceed 0.03 ppm. Overused GFO can release phosphate back into the water.
Can I run GFO and carbon in the same reactor? Yes, but only in dual-chamber reactors (e.g., Reef Octopus BR-110). Mixing them in a single chamber can cause channeling and reduced efficiency. Always use separate media bags if using a single-chamber reactor.
What pump size do I need for a reactor? For most reactors, a pump rated at 150–300 GPH (e.g., Sicce Syncra 1.5) works well. Higher flow can fluidize GFO, causing dust release. Lower flow reduces contact time. Always use the manufacturer’s recommended flow range.
How do I prevent GFO dust from entering the tank? Rinse GFO media in RO/DI water before use. Use a reactor with a pre-filter sponge (e.g., Avast Marine) or a flow control valve to limit flow. Start flow slowly and increase gradually.
Are acrylic reactors better than PVC? Acrylic is transparent (allows visual inspection) and lighter, but can crack if overtightened. PVC is more durable but opaque. For most reefers, acrylic is preferred for visibility and ease of use.
Sources
- Bulk Reef Supply – GFO & Carbon Reactor
- AquaMaxx – HOB GFO/Carbon Reactor
- Two Little Fishies – PhosBan Reactor 150
- Reef Octopus – BR-110 Dual Media Reactor
- Avast Marine – Sponge Filter Reactor
- Tunze – Reef Reactor 9004
- Innovative Marine – Minimax Pro Reactor
- Reef2Reef Forum – Reactor Reviews
Bottom Line
Select the BRS GFO & Carbon Reactor for best overall performance and ease of use in most reef systems. Choose the Innovative Marine Minimax Pro Reactor for budget nano setups. Always match reactor capacity to system size and test phosphate levels weekly.
For dual-media needs, the Reef Octopus BR-110 offers the best separation. Avoid single-chamber mixing of GFO and carbon.
*Top 10 aquarium reactors for running GFO or carbon in reef systems for professional operators.*