2nd Reef tank heater overheat

[Twiztidninja]

So my tank yesterday was 85 degrees when I got home from work. I lost a few corals. I put a new heater in. And today I checked it and it's 83 and still on. what the heck 2 heaters malfunctioned in 2 days. The 2nd one is new and both are set at 78

 

[Potatohead]

If they’re Eheims they need to be calibrated.

Might be worth looking into an Inkbird controller.

 

[ckuhny3]

Helio PTC Smart Heaters

Smart, Safe & Stable Aquarium Heating PTC Solid-State Ceramic Heating Technology Overheat-Resistant Titanium Heating Elements Dedicated Smart Controller with Audible Alarms Remote Titanium Temperature Probe Supports Single or Dual Heating Elements Magnetic Holders for Secure, Tool-Free Mounting...

www.bulkreefsupply.com

 

[Uncle99]

Mine say 84 but actually 77.8.
They are both digital and don’t allow calibration.
There can be wide fluxes in models.
Get a second and third test, see what they say…
Maybe they lie….