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Which HMU option is documented as 400 W?
The official Finnex Shop lists a 400 W HMU choice with SKU HMU-400S and its own Shopify variant ID. Its official variant barcode field is blank, so the UPC is unverified.
Explore this need in the finder →Does Finnex publish a tank-size range for HMU 400 W?
Not in the primary Shop record or the reviewed comparison chart. The chart gives a 100–500 W family span but no capacity band. Do not turn 400 W into a gallon recommendation; this variant remains reference-only.
Explore this need in the finder →What control range can be attributed to HMU 400 W?
Finnex’s comparison chart lists a shared 68–92°F HMU range for its 100–500 W span. This is a manufacturer claim, not an independently measured water temperature; the product still lacks a supported tank capacity and setup.
Explore this need in the finder →Finnex HMU digital titanium series · 400 W · reference-only assessment
The official Finnex Shop has an individually selectable 400 W HMU option. Product JSON maps it to SKU HMU-400S and a unique Shopify variant ID. This is a separate identity, not a controller accessory or a duplicate of the 300 or 500 W choices. Finnex's comparison chart includes 400 W within the HMU line's 100–500 W span, but it does not supply an aquarium-volume band or any exact-size dimensions. The product is real as a catalog configuration; its appropriate operating setup is not established by the sources reviewed.
Published family specifications
Finnex's current grouped Shop description says the HMU uses a titanium heating tube and remote temperature sensor, with adjustable digital controls, a flame-retardant guard and a non-resumable fuse described as cutting power if the element is exposed. The maker's comparison chart reports a steel coil, push controls, digital display, 68–92°F range, non-resumable out-of-water protection and Japanese components for the HMU 100–500 W range. These statements are not test data. The chart does not show 400 W as a different control version; its specific wattage difference from neighboring configurations is the supported model-level distinction.
Power is not a capacity rating
The 400 W number is useful for identifying a higher-output option than HMU-100S, -200S or -300S and a lower-output option than -500S. It is not a manufacturer-backed answer to “How many gallons?” The primary sources do not connect HMU-400S to a tank-size range, target-to-room temperature assumptions or complete setup requirements. A wattage-only comparison cannot account for the aquarium's actual water volume, heat loss, room conditions and circulation. Rather than import ratings from another model or retailer listing, I leave this key fit question open.
What remains to verify
The official variant data has no UPC. The Shop copy does not give complete voltage and frequency, model length, approved water types, full immersion depth, orientation or clearance. The public Finnex instructions index lists manuals for HMH, HMS and HPC heaters but none for HMU, and those related manuals cannot confirm HMU installation. The gallery is shared and does not visibly identify HMU-400S, so no image is used as an exact product photograph. The listing's current sold-out display is not treated as proof of discontinuation. This assessment stays reference-only and is excluded from the finder and purchase landings until exact model documentation fills those gaps.
Evidence checked
See the official Shop configuration, Finnex's comparison chart and the manufacturer instructions index. This is documentary research, not a hands-on trial.
Key specifications
Key details at a glance
| Rated heater power | 400 W |
|---|---|
| Lowest thermostat setting | 68°F |
| Highest thermostat setting | 92°F |
| Temperature control | Adjustable thermostat |
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.