What Heater For My Fluval Edge

[danotto]

I have the standard fluval edge heater in my fluval edge tank but my tick on thermometer is only reading 22 degrees when it used to read 26 is my heater packing up the temperature in the house seems warmer than usual as the mrs has the heating on now. if so whats a small decent heater that will fit well in my fluval edge and wth my fish im guessing i need the tanka round 26 degrees