"James" wrote in message ...
200 watt in a 37 gal tank

Try 50W heater next time.
It will be enough for such a small tank!

If you are afraid 50W will not be enough
(like because you keep thermostat really low
in your fish room) than get 2 heaters, 50W each
instead of one 75W or 100W.

If one 50W fails stuck or open the second will
work OK and turns itself on/off as needed,
minimalizing temperature difference effects...