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Will HeatUp 400 cover an aquarium at its published size limit?
OASE gives this exact 400 W SKU a 400 L technical maximum and also states up to 106 US gallons. Those rounded/source forms differ; this library uses the lower litre conversion, 105.7 US gal, as the conservative maximum. That is not a warm-up or cold-room guarantee. Check actual water volume, room-to-water difference, lid, circulation and livestock needs.
Explore this need in the finder →Can HeatUp 400 be used for saltwater and where does it install?
OASE lists freshwater and saltwater suitability and a fully submerged in-tank holder. For the documented external route, the full named BioMaster 850 setup is required.
Explore this need in the finder →Is HeatUp 400 adjustable for the intended temperature setting?
OASE documents a 66–90°F setting scale. A secondary post-calibration adjustment is described as ±2°F in one US feature block and ±3°C in other product copy; neither is an accuracy tolerance, a measured water reading or a stated degree-by-degree step. Confirm actual water temperature with a separate thermometer and set a species-appropriate target independently. Its quartz tube is not documented as shatterproof. Verify the exact heater label: US technical table says 115 V / 50–60 Hz, while the product narrative says 230 V.
Explore this need in the finder →The OASE HeatUp 400 is the largest wattage in the seven-card US HeatUp family selector: 400 W, SKU 77117, with a 23 mm diameter and a 440 mm (about 17.3-inch) tube. The exact technical table gives a 400 L aquarium maximum, and US marketing copy gives 106 U.S. gallons. Four hundred litres converts to about 105.7 U.S. gallons, so this review uses the smaller 105.7-gallon threshold for matching. That rounding difference is left visible. This is a source-based product assessment, not a heating test, ownership report or stock recommendation.
Longest body, largest published rating
The 400 W model is materially longer than its siblings: 440 mm compared with 370 mm for the 300 W, 315 mm for the 150/200 W and 245 mm for the 100 W. Its wattage rating alone does not tell whether the tube will fit in a tank, and a 17.3-inch heater demands careful measurement of usable interior height, minimum waterline and nearby equipment. Capacity is an upper label, not an assertion that every tank beneath it will reach a target. The temperature difference between room and aquarium, a lid, water movement and actual volume affect demand; the product page does not promise results under each set of conditions.
OASE describes fresh- and marine-water suitability, an adjustable 66–90°F setting scale, bimetal thermostat control, a heating indicator, a thermal shutoff switch, quartz glass, an included holder and a three-year warranty. The source names BioMaster 850 for filter integration. For this review, that is the sole external-filter plan; a heater by itself is not an external inline configuration, and the BioMaster 850 is a separate component that must be present and installed according to the current instructions. Do not transfer integration options from the 300 or 200 W pages to the 400 W model.
How to read the thermostat description
The US-facing family pages give the main scale as 66–90°F and describe a separate calibration adjustment as ±2°F. Other manufacturer feature text calls the secondary adjustment ±3°C. The wording conflict does not mean the heater measures water accurately within those tolerances, nor does the source say the dial has a one-degree step. A lamp identifies active heating rather than displaying current water temperature. An independent thermometer is needed to check real aquarium conditions; an appropriate target must come from the fish and invertebrates being kept.
The outer tube is quartz glass, with OASE describing tolerance of at least twice the temperature of standard glass. That is not a drop test, an impact-resistance rating or proof of shatterproof construction. A thermal shutoff switch is named, but no separate dry-run sensing conditions were established in the exact product evidence. Follow the instructions supplied for the exact device and filter combination; do not create a safety procedure from feature-summary copy.
Do not ignore the conflicting voltage sentence
SKU 77117 appears in the US HeatUp family, and its exact product specification table states 115 V / 50–60 Hz. However, the product-page narrative says 230 V. The table supports a U.S.-edition matching value, but the source conflict means an individual unit still needs checking. Read the carton and the heater’s electrical label before plugging it in. If the device is marked 230 V, do not connect it to a U.S. mains outlet; have the seller or OASE confirm the precise edition. A US category-card identity is not a guarantee about a particular retailer’s box or current stock.
When to put the HeatUp 400 on a shortlist
This version merits comparison only if the aquarium fits within the conservative 105.7-gallon maximum, the adjustable range covers the keeper’s separately selected target, and the unusually long body has a safe place with circulation. If a filter-based arrangement is needed, confirm the named BioMaster 850 and exact current setup instructions. The HeatUp 400 is not documented as shatterproof; buyers who require that exact body claim should not treat “quartz glass” as equivalent. Its maximum does not prescribe a lower size boundary, so smaller aquariums require independent selection and husbandry judgment rather than a claim that 400 W is suitable for every smaller tank.
The model’s 440 mm length, 400 L rating and 400 W draw differentiate it from the 300 W version. That makes separate model review and an exact mounting check useful: a family table is not a substitute for verifying the unit at hand. A finder match represents only the evidence-backed requirements this library can test. It is not a safety certification, stock guarantee, measured temperature result or species-care decision.
Questions to settle before choosing
- Is measured aquarium volume no more than 105.7 U.S. gallons using the lower litre-derived capacity, rather than the rounded 106-gallon ceiling?
- Will a 17.3-inch heater fit while meeting the instructions for water depth and circulation, and is a BioMaster 850 external-filter setup actually intended?
- Does the exact SKU 77117 nameplate confirm 115 V, and is a quartz-glass body acceptable when a shatterproof construction claim is not documented?
Key specifications
Key details at a glance
| Rated heater power | 400 W |
|---|---|
| Manufacturer aquarium rating | 105.7 US gal |
| Lowest thermostat setting | 66°F |
| Highest thermostat setting | 90°F |
| Temperature control | Adjustable thermostat |
| Supported water types | freshwater / saltwater |
| Installation route | Fully submerged, in-tank |
| Heater length | 17.3 in |
| Electrical supply | 115 V |
Use the exact model’s instructions for operating limits, supplied equipment and version differences.
Sources for this review
Sources for this assessment
Check the complete aquarium setup
Use the finder to compare documented tank size, water type, installation and temperature-control fit. A match does not guarantee the keeper's species-specific target or measured performance.