In article t,
says...

Also I purchased a Jager heater 5 months ago and it kept the water w/in
2 degrees of what I had set it at: 82F. Now it won't go over 80F even if I
have the dial maxed out. (I've checked the temp with two thermo's.) Dog of
a heater?



Probably not a bad unit, certainly E-J makes quality heaters. A common problem
with all one piece submersible heaters is that the heating end of the tube can
warm up the water around the top or thermostat end of tube. Then the heater shuts
off prematurely, before the water in the aquarium has reached the setpoint. Two
things that you can do to reduce the impact of this a 1) mount the heater
horizontally and low, or 2) mount the heater next to a filter inlet or outlet that
will provide good circulation around it.

Since you have just added a filter I am guessing that you might have moved the
heater or possibly repositioned it. You might try horizontal mounting if you are
not already doing so. Just turn the dial back to a reasonable position in case
this fixes the problem. If the EJ does not perform as well as it used to, when
mounted horizontally, then I would suspect a bad unit.

I recently set up a new tank with an Hydor In-line heater. These things plumb into
the line between the tank and a canister filter or return pump. The self-heating
problem of submersibles is not a challenge with these, and it is pleasing to
eliminate the heater from the display area of the aquarium. Cost was higher
though, over $40 for a 300W heater. It was worth it for me, in that application.

George