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What is documented for the HMC-400S size?
Finnex lists a distinct 400 W HMC-400S row for 80–100 US gallons, with a 15.1-inch tube and 3.33 A at 110 V. The official Shop product options omit this size, so no exact retail SKU or current offer was verified.
Explore this need in the finder →Does the HMC-400S use a digital display and adjustable setting?
The family page describes the HMC controller as an illuminated digital display with adjustments and lists 68–92°F. It does not give accuracy tolerance or a measured temperature test for the 400 W model.
Explore this need in the finder →Is the HMC-400S documented for an in-tank submersible setup?
Finnex labels the HMC heater submersible, but the reviewed pages do not give the HMC-400S immersion depth, waterline, orientation or mounting procedure. Check the exact HMC instructions before installation; the current support index does not list an HMC manual.
Explore this need in the finder →A 400 W family-table model that the Shop selector omits
Finnex’s HMC specification page explicitly lists the HMC-400S as a 400 W configuration for 80–100 US gallons, with a 15.1-inch tube, 3.33 A at the stated 110 V reference and 68–92°F control. The current grouped Shop product record has options for 100, 200, 300 and 500 W, but not 400 W. The official family row is enough to retain this model as a documented configuration; it is not enough to claim a current retail offer, SKU, UPC, package or stock status.
Its stated length matches the HMC-500S tube length, but the models are not duplicates: the table assigns different wattage, amperage and tank-volume bands. The shared physical length does not reveal internal component differences or tank performance. The lower and upper ranges meet at 100 gallons with HMC-500S; that chart boundary should not be treated as a tested equivalence.
Controller features on the HMC family
Finnex describes the HMC system as having a digital illuminated display and adjustable controller outside the aquarium, a separate sensor, and memory that resumes the last setting after an interruption. It lists a control range of 68–92°F. These are family-level manufacturer statements; there is no HMC-400S accuracy tolerance, independent stability log or recovery test here. A controller’s adjustment range is not a recommendation for fish, coral, plants or invertebrates. Confirm the target separately and use an independent thermometer to check actual tank water.
The source identifies a titanium heating element and flame-retardant guard, and its copy describes freshwater/marine use and labels HMC submersible. The source set does not provide complete placement instructions, an immersion-depth marking, waterline drawing, attachment method or full power-input rating. The inspected manufacturer instructions index has no HMC entry, which is a bounded source gap rather than proof that no instructions exist anywhere.
Limits on retail and image identification
The HMC-400S model code and wattage come from the family page, not from a Shop variant. No exact Shop SKU, variant ID, UPC, package or model-specific offer was found. Because the current Shop selector omits 400 W, a seller’s generic “Finnex digital titanium heater” label would not by itself establish this exact model. Check the code on the product and package before assuming a listing is the HMC-400S.
The current Shop page reuses three images named for HMU across its four listed options, and none identifies HMC-400S. The family page image references are placeholders rather than product photographs. No image is attached to this review as an exact model image. The 3.33 A value is an amperage reference at 110 V only; full acceptable supply voltage and frequency still need the exact label or manual.
Why this assessment cannot enter the finder
At 80 gallons the HMC-400S is at the lower boundary printed by Finnex. The existing matcher has no minimum-volume operation and would otherwise treat any tank up to 100 gallons as a potential match. That would include smaller aquariums outside the table’s 80–100-gallon band. I therefore keep this as a reference-only review without a finder result or ordinary questionnaire-based purchase recommendation. Its separate model-reference lookup provides identification and seller checks, not compatibility approval.
See the separate HMC-300S assessment for the prior 60–80-gallon row and the HMC-500S review for the Shop-listed 500 W model. Their adjacency does not settle which heater is appropriate for a particular tank or substitute for missing installation details. Verify exact model, package, complete electrical rating, setup directions and intended tank conditions independently. No model use or testing is claimed here.
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 |
| Supported water types | freshwater / saltwater |
| Installation route | Fully submerged, in-tank |
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.