The heater in my 55 Mbuna tank apparently ran continuously and I noticed
that about half of the fish couldn't take the temperature - some of the
bigger fish banged into it from time to time - I figured that the heater was
shot - I unplugged the heater, and let the tank water cool down ot house
temperature - around 79 degrees - did a fairly decent water change, changed
the filter media, and things have been fine since then. I've been trying
the heater for brief periods, watching it very closely - the heater seems to
cycle on and off normally, as indicated by the indicator light - once
something like that happens with these heaters, should they just be thrown
away? Or could it be something else? Thanks.