OASE BioStyle Thermo 30 Hang-On Aquarium Filter with Heater, Grey review

A filter-and-heater bundle with a separate question to verify

OASE BioStyle Thermo 30 Grey is item 84068. The exact page names two parts in the US package: a grey BioStyle 30 base, SKU 84065, and HeatUp 25 US, SKU 33798. The filter page gives an up-to-30-US-gallon / 115-L label, a maximum 550 L/h flow, 5 W filter power and 1.9 L total filter volume. It describes the included heater as preset around 79°F. The preset statement is important: this assessment does not transfer every adjustment feature from the separately sold heater page to the Thermo bundle.

That separate official HeatUp 25 page identifies SKU 33798 as 25 W and gives a stand-alone maximum aquarium recommendation of 25 L. The Thermo filter page, by contrast, labels its filtration package for up to 30 US gallons. The sources do not explain how that heater recommendation applies to the bundle. Do not assume that the filter’s gallon ceiling establishes that its included heater is sufficient for every tank near that size; ask OASE to confirm suitability for the actual aquarium, room temperature and temperature target before relying on it as the only heater.

Two media sets and a standard-size body

The filtration side includes two multi-stage disposable cartridges and two biological foams, like the standard 30. OASE describes its cartridge as foam, chemical media and filter fleece, and its separate setup guide advises removing the carbon element during medication treatment. The page’s 1.9 L is total filter volume, not a media basket. No published lower aquarium-volume endpoint or comparable litre basket appears in the reviewed sources.

This is not just a non-Thermo BioStyle 30 with another label. The Thermo SKU packages a heater, the exact finish is grey, and the setup guide says to run the filter first, confirm water is flowing, and only then connect the heater. It also says the heater may be removed and used in the tank with the supplied suction cups. Thermo models do not include the outlet stopper described for standard units. Those differences affect startup and service, so check the instructions for the exact bundle rather than applying all non-Thermo accessories by default.

Installation still depends on the rim and waterline

The HOB arrangement avoids a canister cabinet and plumbing below the aquarium, but it uses the rear tank edge. OASE’s setup guidance calls for glass under one inch thick, a water level no more than 5.5 inches below the rim and a telescopic intake extension from 6 to 14 inches. Leave clearance for the housing, lid, wall, cord and media removal; the maker also advises an intake position above the substrate. These checks are more concrete than simply asking whether there is room under the stand.

Prime the filter with aquarium or filtered water before startup, never run it dry, and use a drip loop. The maximum-only label means this review cannot certify a numeric tank-volume match. Adjustable filter flow does not prove the package meets a high-waste requirement. A newly installed biological filter still needs time to establish; plan monitoring rather than treating a gallon label as an aquarium-care guarantee.

When this package may—and may not—simplify the tank

Combining the filter and heater in one visible HOB housing can suit a layout where two separate devices would be distracting. But it is a package convenience, not a substitute for checking heater capacity and set-point needs. Compare the standard BioStyle 30 if you do not want a bundled heater, and read the navy Thermo 30 review for the finish-only counterpart. Both Thermo 30 colors share the same functional claims in the checked pages, but retain separate exact filter and base SKUs. For Thermo 30 Grey, the defining purchase check is whether the exact 84068 package is what you intend and whether OASE resolves the 33798 heater’s separate page recommendation for your tank.