Name: RS Electrical Submersible Aquarium Heater (100W / 200W / 300W)
Brand: RS Electrical
SKU: RS-HEATER
Availability: InStock
Rating: 4.44 (16 reviews)

Question 1

How do I choose between the 100W, 200W and 300W heater?

Accepted Answer

Select wattage based on your tank volume. As a general rule, use approximately 1–1.5W per litre for a typical Indian home environment. The 100W is appropriate for tanks of 100–130 litres. The 200W suits tanks of 180–230 litres — the most common community and cichlid tank sizes in the 4-foot aquarium range. The 300W is for tanks of 250–330 litres — larger 5-foot community tanks and dedicated Discus setups. For rooms with air conditioning that cools below 20°C ambient temperature, use the next wattage up from the standard recommendation. For tanks over 330 litres, two heaters placed at opposite ends of the tank are recommended over a single oversized heater.

Question 2

Why is it important to unplug the heater before water changes?

Accepted Answer

The RS Electrical heater uses a glass tube containing a resistive heating element. When the element is active, the glass reaches temperatures significantly above the ambient air temperature. If the water level drops below the glass element during a water change while the heater is on, the exposed glass is subjected to the sudden transition from water-cooled temperature to air temperature — this thermal shock causes the glass to crack or shatter. This releases the element into the tank water, which is both an electrical hazard and can send glass shards into the water. Always switch off and unplug the heater before beginning a water change and wait 5–10 minutes before allowing the glass to cool before the water level drops.

Question 3

How do I know if the heater is working correctly?

Accepted Answer

The indicator light on the RS Heater illuminates when the element is actively heating. After installation and setup: set the dial to your target temperature and allow the heater to run for 2–4 hours. Then check the actual tank temperature with a separate aquarium thermometer placed at the opposite end of the tank from the heater. If the temperature matches your target within 1–2°C, the heater is functioning correctly. Adjust the thermostat dial slightly if calibration is needed — this is normal as the markings on the dial are approximate. A heater that runs the indicator light continuously without the tank reaching the set temperature may be undersized for the tank volume or ambient conditions.

Question 4

Can I use the 100W heater for a larger tank?

Accepted Answer

No — using an undersized heater for a larger tank will result in the heater running continuously at full power and still failing to reach the set temperature during cool ambient conditions. Continuous full-power operation significantly shortens heater lifespan. In cooler months or air-conditioned environments, an undersized heater will simply fail to maintain temperature, exposing your fish to cold stress. Always match the wattage to the recommended tank volume. If your tank is borderline between two wattages (e.g. 160L), choose the higher wattage — the thermostat limits heating once the target temperature is reached.

Question 5

Is this heater suitable for Discus?

Accepted Answer

The RS Electrical heater can maintain Discus tank temperatures of 28–30°C. For a Discus tank the specific wattage needed depends on tank size: a 100L Discus-only tank can use the 100W; a 200L Discus community tank should use the 200W. Discus are the most temperature-sensitive of commonly kept ornamental fish — they should not be kept below 27°C and thrive at 28–30°C. For Discus setups we also recommend a separate digital thermometer placed in the tank at all times for accurate temperature monitoring, since the thermostat dial on the heater is approximate and Discus require more precise temperature management than community fish.

Question 6

Is the heater suitable for saltwater/marine aquariums?

Accepted Answer

The RS Electrical heater is a general-purpose submersible glass heater suitable for both freshwater and marine aquariums at the indicated wattages and tank volumes. The glass and suction cup components are chemically neutral and safe for use in saltwater environments. Standard saltwater reef temperature targets of 24–26°C are within the heater's adjustment range. For marine aquariums, monitor carefully for salt creep on the heater body (rinse monthly with clean freshwater) and inspect the suction cups regularly as saltwater degrades rubber faster than freshwater.

Question 7

How long should an aquarium heater last?

Accepted Answer

A quality submersible glass heater used correctly should last 2–5 years. Key practices that maximise heater lifespan: never expose the glass to air while the element is hot (the most common cause of premature failure); keep the glass clean of algae and mineral deposits; ensure full submersion at all times; match wattage to tank size so the heater does not run continuously. Signs to replace a heater: glass cracking or clouding, indicator light failure, temperature control becoming erratic, or any sign of electrical arcing or smell near the power cord. Never operate a damaged heater.

Question 8

Should I install the heater vertically or at an angle?

Accepted Answer

The RS Electrical heater can be installed vertically or at an angle of 45°. Fully vertical installation is common and functional. Horizontal or angled installation (45° tilted toward horizontal) is often recommended because it increases the surface area of the glass in contact with tank water flow, improving heat distribution. Position the heater near the outlet of your filter or a powerhead so that heated water is immediately distributed through the tank rather than creating a warm zone near the heater. Avoid placing the heater directly against the tank base — a small gap below the heater ensures water circulation around the full glass length.

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RS Electrical Submersible Aquarium Heater (100W / 200W / 300W)