Comparison

Compare AquaTop HTG guarded aquarium heaters

AquaTop's HTG family has five separately named guarded glass heaters, not one adjustable product with interchangeable sizes. The current exact pages list 50, 100, 200, 300 and 400 W configurations. This comparison uses each exact model's own wattage, height, water-temperature range and current capacity claim. For the three larger entries, it also preserves older official data-sheet figures that differ from the current product page; the finder uses the lower figure until the package/version relationship is clear.

Compare the five actual size rows

• HTG-50: 50 W, 9.5 inches high, 13 US gallon current-page maximum. The older data sheet also lists 13.
• HTG-100: 100 W, 11.5 inches high, 25 gallons on both current exact page and older data table.
• HTG-200: 200 W, 13.5 inches high, 50 gallons on its current page versus 40 in the older HTG-200W data row. The conservative finder ceiling is 40.
• HTG-300: 300 W, 15.75 inches high, current-page maximum 80 versus older HTG-300W table maximum 60. The conservative finder ceiling is 60.
• HTG-400: 400 W, 18 inches high, current-page maximum 130 versus older HTG-400W table maximum 100. The conservative finder ceiling is 100.

All five are listed as fully submersible, freshwater/saltwater-capable, and adjustable from 68–93°F; every exact page lists a 1.25-inch width and depth. Those shared family statements do not make the units equivalent: wattage, body length and the upper gallon screen differ. The volume screen is a maximum-only comparison, not a minimum-size recommendation or a guarantee of reaching a target in every room.

Read the capacity conflict as a version question

The current exact manufacturer pages identify the suffixless SKUs HTG-200, HTG-300 and HTG-400. AquaTop's older official series table uses HTG-200W, HTG-300W and HTG-400W, with a different maximum listed for each. The sources do not explain whether those codes refer to an earlier retail package, a superseded rating or a physical revision. We therefore do not transfer the older UPCs to the current SKUs or silently discard either source. Instead, this review library keeps the current page claim visible and screens tank volume at the lower historical value: 40 gallons for the 200 W plan, 60 for 300 W and 100 for 400 W. For an exact purchase, compare the paperwork delivered with that package before relying on a higher limit.

The current page and older sheet agree on HTG-50 (13 gallons) and HTG-100 (25 gallons). Those agreements are not evidence for a minimum tank volume. AquaTop's reviewed HTG sources do not quantify room temperature, desired heat rise or operating conditions. A maximum should be read alongside actual working volume, space, lid and circulation rather than turned into a rule of watts per gallon.

Guard, glass and control are separate considerations

AquaTop describes the HTG models as glass heaters with an included outer guard intended to help reduce accidental breakage. No exact page calls the heater body shatterproof or gives an impact-test rating. A guard is not the same claim as a shatterproof body, so these models are excluded if the latter is a hard requirement. The exact pages also list an LED indicator and adjustable dial, but do not define what the light's state means or state a numeric thermostat accuracy. The listed setting range helps screen requested values; it does not measure actual aquarium water or choose a suitable temperature for any animal.

The current product pages support fully submersible in-tank use and fresh or saltwater operation. They do not show an inline external-filter route. The sources reviewed do not include a detailed HTG manual covering mount direction, a waterline mark, start-up delay or cool-down time; those steps should not be borrowed from an unrelated GH model. Check the exact instructions and the physical electrical nameplate, since the reviewed HTG web text did not publish voltage or frequency.

Choose a documented task, not a wattage shortcut

Use the freshwater in-tank adjustable comparison only as a first screen, then set actual volume and any desired dial temperature to check individual limits. The 13-gallon HTG-50 scenario, 25-gallon HTG-100 scenario and 40-gallon conservative HTG-200 boundary preserve those model-specific ceilings. At one gallon above each active cap, that exact size drops from the capacity-only result. For HTG-300 and HTG-400, use the 60-gallon and 100-gallon conservative tests, then review the underlying page/table discrepancy.

The page says 68–93°F for each HTG size, so 67°F and 94°F fall outside the documented endpoints while 68°F and 93°F fall within them. These are setpoint boundaries, not water measurements or husbandry recommendations. Verify the actual temperature with an independent thermometer, read the current package manual and confirm electrical fit. If the version or label needed for a safe decision is unavailable, do not assume a match proves suitability.

Primary sources: AquaTop's HTG family listing, five exact-model pages for HTG-50, HTG-100, HTG-200, HTG-300 and HTG-400, plus the HTG series data sheet.