Finnex HMS-500S 500 W Digital Titanium Aquarium Heater

Exact-model photograph is not verified. This reference landing is text-only. The official HMS-series visual on the full review shows family components but does not identify the 500 W size or any retail package; it is not presented here as an exact HMS-500S product photo.

Finnex’s 2020 HMS manual gives HMS-500S its own 500 W, 100–120 US-gallon row and a 15.16-inch titanium tube. The 100-gallon lower edge cannot be screened by the finder’s maximum-only volume rule, so this is a reference lookup rather than an eligible finder match. Its remote sensor and temperature-limited low-water system are important installation constraints.

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Documented model details

• Finnex’s September 2020 HMS manual identifies an exact HMS-500S row: 500 W, 4.50 A at a stated 115 V reference, a 100–120 US-gallon band, 50–94°F control range, 55-inch power cord, 47-inch controller-to-heater lead, 47-inch sensor cord and 15.16-inch heater tube. The 115 V current reference is not a complete voltage/frequency supply rating.
• The manual describes 0.1°F adjustment increments and a stated ±0.5°F display accuracy. These are manufacturer specifications, not independent measurements of temperature stability throughout an aquarium.
• Within the six HMS rows in that manual, the 500S is distinct from the 300S: its band is 100–120 gallons rather than 80–100, its tube is 15.16 rather than 12.40 inches, and its controller lead is 47 rather than 39 inches. These are configuration differences, not a claim that every tank in either band will heat as desired.
• The heater itself must remain fully immersed and secured in moving water in an aquarium or sump. The HMS instructions place the separate water sensor underwater, slightly above the tube and directly below its cord clip with no slack; they call for 15 minutes of water-temperature acclimation before power, a drip loop and a GFCI-protected outlet.
• Finnex’s manual describes low-water shutdown and an audible alert when the sensor is exposed, but says the system functions only from 58–92°F. Outside that range it is disabled, and the manual warns the heater can continue heating with the sensor out of water. Never operate the heater outside the water.
• The family page describes a titanium tube, included protective guard and freshwater or marine use, while requiring water above 150 ppm TDS. That is the maker’s family-level condition, not species-specific suitability or a reef-compatibility assessment.

Limits to weigh

• The manual’s 100–120 US-gallon band includes a meaningful 100-gallon lower edge, but the current matcher tests the upper capacity only. The product is held out of finder matches rather than being shown for smaller tanks; this does not establish a universal safe minimum for all aquariums.
• The 120-gallon ceiling does not promise performance under particular room temperature, cover, circulation, target temperature or heat-loss conditions. No tank heat-up or steady-state performance was measured.
• The manual’s 4.50 A at 115 V entry is only an amperage reference; the full supply voltage and frequency for an individual unit are not established. The exact retail SKU, UPC and current seller offer also remain unverified in the bounded Shop sources.
• The low-water protection system is not general dry-run protection: Finnex’s manual limits it to 58–92°F, says it is disabled outside that range and warns the heater may continue to heat when the sensor is exposed.
• No exact HMS-500S wattage-marked product/package photograph is verified. The approved HMS-series visual is family-scoped and does not identify this wattage or a seller’s package; this reference remains text-only. No current price, stock, exact Amazon listing or package contents are asserted.

Check before ordering

• If evaluating a manually found offer, confirm the heater and carton say Finnex HMS-500S / 500 W and inspect the actual electrical label for its full supply rating; the manual’s 115 V amperage column is not that nameplate. Do not treat the absent current Shop SKU/UPC bridge as proof that no listing exists.
• Measure the exact 15.16-inch tube and plan the 55-inch power cord, 47-inch controller lead and 47-inch sensor lead without assuming extension use is permitted. Make room for full immersion, suction-cup mounting, circulation and the remote probe’s position just above the tube beneath its clip.
• Follow the current unit manual for 15-minute acclimation, GFCI and drip-loop precautions, complete immersion, cooling before removal and sensor cleaning. Do not rely on the low-water warning outside its documented 58–92°F active range, and never run the heater dry.
• Check that operating water is above Finnex’s stated 150 ppm TDS condition before relying on the family page’s freshwater/marine description. Do not infer that the generic wording covers a particular fish, coral or livestock temperature requirement.
• Confirm the actual offer, model suffix, package, return terms and supplied instructions before purchase; the retained manufacturer evidence does not establish a current seller or delivered assembly.