A good aquarium heater lasts about 2-5 years and is designed to run 24/7, cycling on and off automatically. Replace it when the thermostat becomes unreliable - or every ~3 years as insurance on a valuable tank.
How long do heaters last - and when to replace
Most quality heaters run 2-5 years. Replace sooner if it struggles to hold temperature, the light stops cycling, it runs hot, or it fails the thermostat test. On prized tanks, many keepers swap heaters preventively every ~3 years, since a stuck thermostat is the main risk (see heater safety).
Can you leave a heater running 24/7?
Yes - heaters are meant to run continuously. The thermostat switches the element on only when the water drops below the set point, and off once it's reached, all day and night. You don't set "hours" - it self-regulates, running more on cold nights and less in warm rooms.
Is heater noise normal?
An occasional soft tick or click as the thermostat switches is normal. Persistent buzzing, crackling or rattling is not - check it's fully submerged and secure, and replace it if the noise continues, as it can signal a failing element.
Winterising in cold regions
In North India and hill stations, cold snaps make the heater work harder. Size up a wattage (see our size guide), keep a lid on to hold heat, move the tank away from cold windows and drafts, and check the temperature holds as the room cools. A titanium Hygger HG085 or reliable Fluval handles the extra load well.
Simple maintenance
- Unplug before water changes, and let it cool before lifting it out of the water.
- Gently wipe algae or scale off the tube during cleaning.
- Keep it fully submerged and the suction cups firm.
Choosing a replacement? See our pillar guide - best aquarium heaters in India.
Frequently asked questions
How long does an aquarium heater last?
Typically 2-5 years; replace sooner if it can't hold temperature or fails a thermostat test.
How often should I replace my aquarium heater?
When it becomes unreliable, or preventively every ~3 years on valuable tanks, since a stuck thermostat is the big risk.
Can I leave an aquarium heater on 24/7?
Yes - heaters are designed to run continuously and cycle on and off via the thermostat.
How many hours a day should a heater run?
It self-regulates - it runs only when the water dips below the set point, so more on cold nights and less in warm rooms.
Is it normal for my heater to make noise?
An occasional click is normal; persistent buzzing, crackling or rattling means you should check and likely replace it.
How do I winterise my aquarium heater?
Size up the wattage, keep a lid on, avoid cold drafts, and check the temperature holds as the room cools.
Time for a new heater? Shop reliable Fluval and Hygger heaters at Fish Bazaar, delivered across India.
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