Real owners lean toward the Fluval FX6: 77% of 349 owners recommend it, vs 45% of 22 for the AquaClear 70 Power Filter.
Verdicts aggregated from Reddit, enthusiast forums, and YouTube owner comments — affiliate reviews excluded. Sample sizes differ; judge accordingly. How we score
Owners of both filters report dependable, long-term reliability, with each drawing a strong core of satisfied users alongside a minority reporting quirks or failures. The Fluval FX6's fans praise its huge media capacity and powerful flow for big tanks, months between cleanings, and a self-priming drain valve, but flag its steep price against SunSun canisters, its bulk, a finicky prime that gurgles unless below water level, and occasional leaks or motor and valve failures. The AquaClear 70's owners widely regard it as the best hang-on-back filter, valuing a customizable media chamber that works like a canister for less money and units that run reliably for years or decades, though some find it finicky to restart after a power cut or once the impeller gets dirty, and its strong outflow often needs taming, with a few pulling it off planted tanks to stop it blasting plants. Owners of large or messy tanks needing heavy canister filtration gravitate toward the FX6. Those wanting a flexible, canister-like hang-on-back filter for planted or refugium setups at lower cost lean toward the AquaClear. Neither is simply better; the choice hinges on tank size and whether canister capacity or a customizable HOB fits the setup.
Owners of both filters report dependable, long-term reliability, with each drawing a strong core of satisfied users alongside a minority reporting quirks or failures. The Fluval FX6's fans praise its huge media capacity and powerful flow for big tanks, months between cleanings, and a self-priming drain valve, but flag its steep price against SunSun canisters, its bulk, a finicky prime that gurgles unless below water level, and occasional leaks or motor and valve failures. The AquaClear 70's owners widely regard it as the best hang-on-back filter, valuing a customizable media chamber that works like a canister for less money and units that run reliably for years or decades, though some find it finicky to restart after a power cut or once the impeller gets dirty, and its strong outflow often needs taming, with a few pulling it off planted tanks to stop it blasting plants. Owners of large or messy tanks needing heavy canister filtration gravitate toward the FX6. Those wanting a flexible, canister-like hang-on-back filter for planted or refugium setups at lower cost lean toward the AquaClear. Neither is simply better; the choice hinges on tank size and whether canister capacity or a customizable HOB fits the setup.
Owners point the AquaClear 70 Power Filter at owners who want a customizable media chamber, similar to a canister filter but cheaper, and planted or reef HOB setups running refugium media like chaeto, floss, and purigen.
Owners point the Fluval FX6 at large-tank owners from 75 gallons up to 400, and turtle and messy-fish keepers needing heavy filtration.
The most-cited downside of the AquaClear 70 Power Filter is can be finicky to restart after a power outage or once the impeller gets dirty, sometimes needing repriming or grinding/failing to cycle water at all. For the Fluval FX6, it's expensive, especially next to SunSun.