OASE BioStyle 30 Hang-On Aquarium Filter, Grey review

Read the exact 30 SKU, not just “BioStyle”

The grey OASE BioStyle 30 is US item 84065, a powered hang-on-back filter with an up-to-30-US-gallon product label. The specification page also prints 115 L; those paired labels are maker claims rather than a conversion supplied by this review. No lower endpoint appears in the exact model evidence. A 30-gallon ceiling therefore does not by itself prove fit at a particular volume, and it says nothing about species, waste production or the maintenance schedule an aquarium needs.

OASE also identifies the standard 30-size in Navy (SKU 84059) and White (SKU 84071) on separate US model pages. Those exact pages list a 115-L maximum, 154 × 230 × 212 mm body, 120 V / 60 Hz supply, 4 W, 550 L/h maximum-flow label and 1.9 L total filter volume; no lower tank endpoint or media-basket volume is supplied. The listed net weights differ slightly (1.038 kg for Navy and 1.01 kg for White), while the product category and listed housing dimensions remain the same. Their pages do not spell out a full box inventory in the accessible specification view, so check the exact package before treating the Grey SKU 84065 media list as guaranteed for another finish. The Grey item itself has a separate route conflict: its current page lists 5 W / 150 GPH while an alternate exact route lists 4 W / 145 GPH; both give 550 L/h. That disagreement is not evidence that color changes filtration performance.

The exact White 84071 product page now exposes a separate page-associated image that visibly matches the White finish; it is shown above rather than the earlier dark-looking image candidate. As with the other finishes, verify the SKU and package on the exact listing because the page does not provide a lower volume endpoint or a complete box inventory.

There is an additional source detail worth keeping in view: OASE’s current US product route lists 5 W and 150 GPH, while its alternate exact US route for the same SKU lists 4 W and 145 GPH. Both routes say 550 L/h. That is a manufacturer-page discrepancy, not an invitation to select the figure that looks more persuasive. The listed maxima are not independent measurements of flow after the cartridges become loaded or of circulation through a particular tank layout.

Two cartridge positions; no bundled heater

The manufacturer describes two disposable multi-stage cartridges and two 30-ppi biological foams in the BioStyle 30 package. The cartridge description names foam, chemical media and fleece layers; the separate foams provide a different media element and are not a litre measurement. OASE lists 1.9 L as filter volume, but the public sources do not call that a media basket. Do not use it to answer a hard canister-basket minimum. The standard grey SKU is not the same package as the Thermo 30, which adds a size-matched heater bundle and carries its own product SKU.

The cleaning indicator is a reminder to inspect or replace media, not a precise service interval for every aquarium. The manufacturer guide says to rinse the media before first use and not to open the disposable cartridge. It also says carbon should be removed while fish medication is being used, because carbon can absorb treatment. Those instructions affect how much flexibility the ready-made cartridge offers: check whether a supplied carbon cartridge is appropriate for the current care task instead of assuming all media can stay in place.

HOB fit is a measured installation question

Unlike a canister, this filter hangs on the tank and does not need a below-aquarium cabinet or hose run. The benefit depends on a compatible rim and enough free room behind the tank. OASE’s setup guide specifies glass below one inch thick, a telescopic intake from 6 to 14 inches, and a water level no more than 5.5 inches below the rim. The intake should sit a short distance above substrate; check the exact setup guide for the placement details. A hood, trim, wall, or nearby light can block the filter or make lifting it for service awkward even when the cabinet below is empty.

The pump must be primed with water before use and never run dry. For a new setup, plan an established biological media source and monitor water quality rather than treating a manufacturer’s gallon ceiling as proof the filter is cycled or suitable for a particular load. The adjustable control changes output, but it is not a published high-waste qualification.

Choose between standard and Thermo by package

Choose the grey 84065 only when the standard filter package is what you need. It is distinguishable from grey Thermo SKU 84068, which bundles a heater and has a preset-temperature claim; the exact Thermo page also raises a separate question about the heater’s stated stand-alone application. For a larger chamber and third cartridge/foam position, compare the BioStyle 50 assessment. For a heater package, see the Thermo 30 review and confirm the complete bundle before ordering. The 30’s main strength is its compact HOB arrangement and two-part media package; its main limits are upper-only sizing, unclear basket volume and route-specific specification conflicts.