Aquarium Heater

An aquarium heater is essential for maintaining the stable tropical temperatures that most planted tank inhabitants require. Tropical fish and plants thrive in water between 24–28°C (75–82°F), and even small temperature fluctuations can cause stress, disease, and inhibited growth. A reliable, accurately calibrated heater is one of the most important pieces of equipment in your setup.

Types of Aquarium Heaters

Submersible Glass Heater

The most common and affordable type. A glass tube containing a heating element with an adjustable thermostat, fully submerged in the tank.

• Pros: Cheap, widely available, works well for most setups.
• Cons: Visible, fragile glass, can be inaccurate.

Inline Heater

Installed in the canister filter's return hose, outside the tank. Water is heated as it flows through.

• Pros: Invisible, no equipment in the tank, even heat distribution.
• Cons: More expensive, requires compatible hosing, slightly larger footprint.

Titanium Heater

A metal heating element with an external digital controller. Extremely durable and precise.

• Pros: Unbreakable, highly accurate, adjustable controller.
• Cons: Expensive, controller requires positioning outside the tank.

Sump Heater

Any submersible heater placed inside the sump rather than the display tank.

• Pros: Hidden from view, doesn't affect display aesthetics.
• Cons: Requires a sump setup.

Sizing Guide

| Tank Volume | Recommended Wattage | |---|---| | Up to 30L | 25–50W | | 30–60L | 50–100W | | 60–120L | 100–150W | | 120–250L | 150–250W | | 250L+ | 250–300W or dual heaters |

Rule of Thumb: 1 watt per litre for rooms at normal ambient temperature. In cold rooms, increase to 1.5–2 watts per litre.

Placement & Safety

• Position near the filter intake or outflow to ensure heated water circulates evenly.
• Angle the heater slightly (at ~45°) for efficient heat convection.
• Never operate a heater outside of water — it will overheat and crack.
• Use a controller: An external temperature controller adds a safety layer, cutting power if the heater malfunctions.
• Dual heaters: For large tanks, use two smaller heaters instead of one large one — if one fails, the other provides backup.

Trusted Brands

• Eheim Jäger: The industry standard for reliable glass heaters.
• Hydor ETH: Inline heater — invisible and precise.
• Cobalt Aquatics Neo-Therm: Flat, modern design with accurate digital thermostat.
• Oase HeatUp: Integrated with Oase filtration systems.
• Finnex: Titanium heaters with external digital controllers.

Pros & Cons

Advantages

• Temperature Stability: Prevents dangerous fluctuations.
• Essential for Tropicals: Most popular fish and plants require heated water.
• Adjustable: Dial in precise target temperatures.

Considerations

• Aesthetics: Glass heaters are visible and can be unsightly.
• Failure Risk: Stuck-on heaters can overheat and cook the tank — use a controller.
• Glass Fragility: Standard heaters can crack if bumped.
• Electricity Cost: Continuous power consumption.