I replace my heaters about every 1-1.5 years regardless if they are working or getting flaky. I have had too many fail on me in the past to not do so as well as always have an extra on hand just in case.
@gregg I have been running the Colbalt Neo-therm heaters for the past several years and so far have not had an issue with them. They maintain a very stable temp with no adjustments needed. I use those Bayite temperature controllers as a fail safe in case the heater fails, an alarm goes off or kills power to the heater. I keep my house at 68f at night and and a 200w is more than enough for my 75g at 76F. The BRS titanium heaters are supposed to be fairly reliable as well.
Cobalt Neo-Therm heaters are very unique. They have a super thin profile that allows them to fit into tight spaces like on AIO compartments, or sump baffles. With its easy to set and easy to read control system, setting a heater has never been this easy. Easy to set "One Touch" control...
www.bulkreefsupply.com
bayite Temperature Controller BTC201 Pre-Wired Digital Outlet Thermostat, 2 Stage Heating and Cooling Mode, 110V - 240V 10A: Amazon.com: Industrial & Scientific
www.amazon.com