Comparison
Compare OASE HeatUp 25–400 W aquarium heaters
OASE's US-oriented HeatUp selector contains seven exact model cards. This comparison keeps each wattage, SKU, published capacity and body length attached to its own product rather than treating “HeatUp” as one interchangeable heater. The manufacturer pages describe an adjustable quartz-glass design, but the US technical tables list 115 V while product narrative copy says 230 V; check the actual unit label before powering it. All models are listed for freshwater and saltwater and have a 66–90°F setting scale. OASE's separate calibration wording (±2°F in one US feature block versus ±3°C in other copy) is not an accuracy claim. A separate thermometer is needed to verify actual water temperature.
Seven distinct ratings and physical lengths
| Model / SKU | Power | OASE metric maximum | US gallon wording | Conservative library ceiling | Listed length | Documented filter integration |
|---|---|---|---|---|---|---|
| HeatUp 25 / 33798 | 25 W | 25 L | up to 10 gal | 6.6 US gal | 205 mm / 8.1 in | In-tank holder; no external plan established |
| HeatUp 50 / 33799 | 50 W | 50 L | up to 15 gal | 13.2 US gal | 205 mm / 8.1 in | BioPlus 50 integration is internal; no external plan established |
| HeatUp 100 / 33802 | 100 W | 100 L | up to 30 gal | 26.4 US gal | 245 mm / 9.6 in | FiltoSmart 100 + ThermoFit 48507 (adapter separate) |
| HeatUp 150 / 33803 | 150 W | 150 L | up to 40 gal | 39.6 US gal | 315 mm / 12.4 in | BioMaster 250 |
| HeatUp 200 / 33804 | 200 W | 200 L | up to 55 gal | 52.8 US gal | 315 mm / 12.4 in | BioMaster 350; FiltoSmart 200 instead requires separate ThermoFit 48532 |
| HeatUp 300 / 33805 | 300 W | 300 L | up to 80 gal | 79.3 US gal | 370 mm / 14.6 in | BioMaster 600; FiltoSmart 300 instead requires separate ThermoFit 48567 |
| HeatUp 400 / 77117 | 400 W | 400 L | up to 106 gal | 105.7 US gal | 440 mm / 17.3 in | BioMaster 850 |
“Conservative library ceiling” is the lower of the published litre maximum converted using 3.785411784 litres per US gallon and the product page's US gallon wording. The underlying maximum pair remains visible because the two forms differ, including the pronounced 25 L / 10 gallon gap. These ceilings screen only the maximum; the maker's tables do not supply minimum tank sizes, room-temperature calculations or guaranteed temperature-rise results. Consider actual water volume, ambient temperature, tank cover, circulation and the animals' separate care requirements.
Separate in-tank and external-filter plans
Every exact HeatUp page describes a submersible in-tank arrangement with a suction-cup holder. A filter-integration feature is not blanket permission to place any HeatUp into any plumbing. OASE identifies model-specific filter combinations: 100 W with FiltoSmart 100 and the additional ThermoFit 48507, 150 W with BioMaster 250, 200 W with BioMaster 350 or a FiltoSmart 200 plus ThermoFit 48532, 300 W with BioMaster 600 or a FiltoSmart 300 plus ThermoFit 48567, and 400 W with BioMaster 850. The named external filter must actually be part of the setup, and ThermoFit parts are not included. The library uses one exact external combination per plan; it does not transfer a neighbor's filter compatibility to another wattage.
Wattage and height both rise through the family, but not in equal steps: the 150 and 200 W bodies are both 315 mm, while filter integration differs. The 25 and 50 W units are each 205 mm; their separate upper capacities and wattages remain distinct. Measure the clear aquarium space and read the exact current manual for immersion depth, placement and filter setup before selecting an installation route. A source page's general “easy installation” phrase is not a substitute for those instructions.
Important evidence limits
OASE's U.S. technical specification tables state 115 V / 50–60 Hz, but the narrative description on the same US-oriented product pages says 230 V. The 115 V table is the value represented for the US-listed SKUs in the finder; this source conflict makes checking the physical carton and nameplate essential. If the unit says 230 V, do not use it on U.S. mains. Contact OASE or the seller rather than assuming the selector card determines the specific device in hand.
OASE describes a quartz-glass tube and relative resistance to temperature compared with standard glass. That does not establish impact resistance or a shatterproof-body claim. The pages name a thermal shutoff switch but do not establish a separate dry-run cutoff in this review. Likewise, the adjustable scale is a setpoint range rather than live water-temperature feedback. No model in this family should be selected on the assumption that a listed maximum guarantees a desired temperature under all room and tank conditions.
For the actual evidence, read the seven 25 W, 50 W, 100 W, 150 W, 200 W, 300 W and 400 W model assessments. The heater sizing guide explains why the maximum is only a screen, and the installation guide distinguishes an in-tank mount from a documented external-filter route. Use the finder to compare supported conditions; no shortlist is a compatibility or performance guarantee.