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What aquarium volume does Finnex list for the HMS-500S?
The exact HMS manual lists a 100–120 US-gallon range for HMS-500S at 500 W. That is a manufacturer band, not an independently tested guarantee; the max-only finder cannot enforce its 100-gallon minimum. The product therefore remains outside finder matches rather than being treated as suitable for every smaller volume.
Explore this need in the finder →How does the HMS-500S control temperature and sense water conditions?
The HMS manual documents a 50–94°F adjustable digital setting with 0.1°F increments and stated display accuracy of ±0.5°F. That is the maker’s display specification, not a measured stability result. The HMS-500S uses an external water sensor separate from the titanium tube. Finnex’s HMS manual says to position the probe slightly above the tube, just below its clip without slack, and keep it submerged near the heater; this is different from HMH’s built-in sensor arrangement. The family page also requires water above 150 ppm TDS.
Explore this need in the finder →Can the HMS-500S be installed inside an aquarium?
The HMS manual requires the heater itself fully submerged in the aquarium or sump, secured with suction cups in moving water, and its remote sensor underwater near and slightly above the tube. Allow 15 minutes for temperature acclimation before power; use a GFCI outlet and drip loop. Within the manual’s 58–92°F low-water protection range, exposure stops heating and sounds an alert; outside that range the low-water system is disabled and the manual warns the heater may continue heating. The manufacturer describes freshwater and marine use but requires water above 150 ppm TDS; verify water chemistry, exact supply rating and exact package instructions.
Explore this need in the finder →The longest HMS configuration in the table
The HMS-500S is the highest-wattage HMS model listed in the manual: 500 W for 100–120 US gallons. Its 15.16-inch titanium tube is the longest HMS option, 2.76 inches longer than the 300 W HMS-300S and nearly 9 inches longer than the 50 W model. Measure the submerged mounting area and check that the tube can be secured with open circulation around it. A large tank’s nominal volume does not alone establish that the long element fits or that the stated band is adequate for the room temperature, lid and water movement.
Finnex specifies 4.50 A at its 115 V table reference, plus a 55-inch power cord, 47-inch controller-to-heater lead and 47-inch sensor cord. The longer controller lead is a practical distinction from the 300 W HMS model’s 39 inches, while the main power cord remains 55 inches. These dimensions support planning, not a claim of extension-safe installation. The table does not supply a complete nominal voltage/frequency for the exact heater. No model-specific current Shop SKU, UPC or individual offer was resolved in the inspected collection and HMS search; verify the exact box and electrical label instead of assuming an offer’s title is enough.
Remote sensing adds a placement constraint
HMS-500S uses a separate sensor, unlike the HMH-500S’s built-in sensing point. Finnex says to secure the probe beneath the sensor cord clip with no slack, slightly above the heater tube and underwater. It needs to stay near the tube while remaining in the water it is meant to monitor. The heater itself must be fully submerged, attached to glass with suction cups and positioned where water circulates. Finnex suggests filter or wavemaker flow and permits placement in a filter sump; neither direction describes an inline canister-filter hose installation. In a large system with a sump, plan the 15-inch tube and probe route before setting the controller.
The stated controller range is 50–94°F with 0.1°F adjustment increments and ±0.5°F display accuracy, according to Finnex. That is not evidence of independently measured tank stability. Compare it with an external thermometer. The low-water cutoff/alarm works only from 58–92°F; outside that range it is disabled, and Finnex warns that the heater may continue heating with the sensor out of water. The manual also describes an audio alarm above 95°F and says to unplug the heater and investigate. A broader adjustable range should not be described as broad dry-run protection.
Respect the manual’s start, stop and cleaning steps
Allow 15 minutes for water-temperature acclimation before connecting the HMS-500S. Use a GFCI-protected outlet and drip loop. Before cleaning, unplug aquarium appliances; after disconnection, allow at least 15 minutes for cooling before removing the heater. Finnex calls for a 30-day check and cleaning of the remote sensor, which is the part that must stay in its correct position for the controller and low-water system to interpret the setup. If a low-water event occurs in its active range, restore immersion and follow the manual’s reset instructions rather than immediately assuming it has resumed normal operation.
Why the 100-gallon floor stays visible
Finnex’s 100–120 gallon range is not interchangeable with the other HMS bands. The 100-gallon lower edge is a genuine source boundary, but the public finder enforces only the maximum and would show a 500 W unit for smaller volumes unless the model is held out. HMS-500S remains reference-only. Finnex describes freshwater and marine suitability but requires water above 150 ppm TDS; that condition is not represented in the current public choices. The missing full supply label, individual current retail identity and exact-model image are additional limitations.
The most useful paper identifiers are the HMS-500S suffix, 500 W, 100–120 gallon band, 15.16-inch tube and 47-inch controller lead. The assessment can help compare a real label and setup with the manual, but it is not a product test, availability claim or recommendation of a fish- or coral-specific temperature.
Key specifications
Key details at a glance
| Rated heater power | 500 W |
|---|---|
| Lowest thermostat setting | 50°F |
| Highest thermostat setting | 94°F |
| Temperature control | Adjustable thermostat |
| Supported water types | freshwater / saltwater |
| Installation route | Fully submerged, in-tank |
| Heater length | 15.16 in |
Use the exact model’s instructions for operating limits, supplied equipment and version differences.
Paper, software and setup details
Manual-recommended aquarium range
100–120 US gal
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.