Fluval 307 vs Fluval FX2: Which Canister Filter Fits Your Tank Size?
The Fluval 307 and FX2 canister filters compared on rated tank size, flow, media volume, priming, and maintenance for planted aquariums.
Tank size decides this one. Fluval recommends the 307 for 40-70 US gallon aquariums, while it rates the FX2 for an aquarium capacity of up to 175 US gallons. On a typical 40 to 70 gallon planted tank, the 307 is the size Fluval designed for. On larger tanks, roughly 75 gallons and up, the FX2's higher flow and 9.5 L filtration volume are the better match. The two also differ in priming: the 307 uses a manual instant-prime handle, while the FX2 primes itself electronically and pauses briefly every 12 hours to purge air.
What we compared
Both are Fluval canister filters often considered for mid-size and larger planted tanks. We compared them on:
- Rated tank size. What Fluval states each filter is for.
- Flow. Pump output and Fluval's filter circulation figure.
- Media room. Basket, biological, and total filtration volume.
- Physical size and head height. What fits in the cabinet and how far below the tank it can sit.
- Priming and routine maintenance. Starting the filter, servicing it, and parts the manuals call for.
All figures come from Fluval's user manuals, listed under Sources. We have not tested either filter hands-on.
Side by side
| Product | Fits | Best for | Skip if |
|---|---|---|---|
 Fluval 307 Performance Canister Filter (307)Model A446 | 40–70 gal; low-tech tanks, CO2 tanks | A 40-70 US gal planted tank where you want external filtration with room for media. | Your tank is outside the 40-70 US gal range Fluval specifies for this size. |
 Fluval FX2 High Performance Canister Filter (FX2)Model A213 | up to 175 gal | A large planted tank (roughly 75 gal and up) where you want one high-capacity canister. | Your tank is small enough for a 07-series or hang-on-back filter. |
| Spec | Fluval 307 (A446) | Fluval FX2 (A213) |
|---|---|---|
| Rated tank size | 40-70 US gal (90-330 L) recommended | 175 US gal (750 L) aquarium capacity; no minimum stated |
| Pump output | 303 US gal/h (1150 L/h) | 475 US gal/h (1,800 L/h) |
| Filter circulation | 206 US gal/h (780 L/h), same-length hoses | 343 US gal/h (1,300 L/h), without media, same-length hoses |
| Media | 3.1 L basket volume; 4.5 L total chamber volume | 3.9 L biological volume; 9.5 L filtration volume |
| Mechanical pre-filter | 803 cm2 vertical pre-filter area | 1,150 cm2 (178 sq in) foam area |
| Canister | 7.3 L canister volume; 9.5 x 7 x 16.5 in (24 x 18 x 42 cm) | Dimensions not stated in the sources we cite |
| Max water column / head height | 1.75 m | 2.1 m (6.9 ft) |
| Priming | Attached instant-prime handle | Electronic automatic priming |
| Power | Not stated in the 07 manual excerpt we cite | 27 W (120 V/60 Hz) |
| Warranty | Not stated in the sources we cite | 3 years |
The circulation figures are not measured the same way: Fluval notes the FX2 figure is without media, and the 307 figure is with same-length intake and output hoses. Treat them as a rough guide, not a direct match.
Choose the Fluval 307 if
- Your tank is 40 to 70 US gallons. That is Fluval's recommended range for this size, based on North American standard aquarium usage.
- Cabinet space is tight. Fluval lists the 307 at 9.5 x 7 x 16.5 inches.
- You want a hose shutoff for service. The AquaStop valve shuts off flow and locks the hoses to the canister cover for maintenance.
- You might own more than one 07-series filter. The 07 series shares its platform and service parts across sizes. Our Fluval 307 review and Fluval 07 series vs EHEIM classic comparison cover the line.
Choose the Fluval FX2 if
- Your tank is above the 307's range. The FX2 is rated for up to 175 US gallons, which suits a large planted tank of roughly 75 gallons and up.
- You want one high-capacity canister. The 9.5 L filtration volume gives more room for media than the 307's 4.5 L chamber volume.
- You want automatic priming. The FX2 primes electronically after plug-in.
- The filter sits well below the tank. The listed maximum head height is 2.1 m, compared with 1.75 m for the 307.
When neither is right
- Your tank is under 40 gallons. The 307 is rated from 40 gallons, and the FX2 is a large canister for a small tank. Look at the smaller 07-series sizes or a hang-on-back filter in our filter picks.
- Your tank is over 70 gallons and you want no flow pause. The FX2 stops for 1 minute every 12 hours by design, and the 307 is rated only up to 70 gallons. Compare other large filters on the Filters: what to check before you buy ↗ hub.
- You do not want to service hoses and gaskets. Any canister needs more upkeep than a hang-on-back filter. Our filter guide compares filter types.
Compatibility and maintenance differences
Priming. The 307 starts with an attached instant-prime handle, per the manual. The FX2 primes electronically after plug-in, and the pump stops for 1 minute every 12 hours to evacuate trapped air. This short pause is by design and is not a fault.
Servicing. On the 307, close the AquaStop valve to shut off flow and lock the hoses to the cover before you open the canister. The manual calls for lubricating the gasket and for yearly replacement of the motor head gasket and impeller as preventive maintenance. For the FX2, follow the maintenance steps in the FX manual listed in the sources.
Flow in a planted tank. Higher flow helps carry CO2 and nutrients around a large tank, but strong flow can also flatten delicate stems in a small one. Match the filter to the tank volume Fluval states rather than buying the largest model.
Placement. Both sit below the tank. Keep within each filter's listed maximum head height: 1.75 m for the 307, 2.1 m for the FX2.
How we chose
- Same maker, different size classes. These two are a common choice for buyers whose tanks sit near the top of the 07 series' range.
- Specifications from Fluval's user manuals, listed in the sources. Where a source does not state a figure, the table says so.
- Identity confirmed against the retail listing for each exact model.
- Research-based. We have not tested these filters hands-on. There are no scores or rankings, and the right choice depends on your tank volume.
Related guidance
Sources
- Fluval 07 Series canister filter user manual (doc 09520001), Rolf C. Hagen (PDF hosted by Fishkeeper UK)
- Fluval FX2/FX4/FX6 canister filter user manual, Rolf C. Hagen
This page is research-based: we have not tested the equipment or methods ourselves. It draws on the sources listed and established hobby practice.
Keep reading
Choosing a Filter for a Planted Aquarium
How canister, hang-on-back, sponge, and internal filters suit planted tanks, how to size flow realistically, and how to maintain media without harming the cycle.
Best Filters for Planted Tanks: Canisters and HOB Picks by Tank Size (2026)
Canister and hang-on-back filters for planted tanks, grouped by the maker's rated tank volume, with media capacity, placement, and maintenance notes.
Fluval 307 Canister Filter Review (2026): Specs, Fit, and Upkeep
Fluval's 307 canister is rated for 40-70 US gal tanks. Its published specs, fit, upkeep, and how it compares with the 207, 407, and EHEIM classic 350.