"h153" wrote in message
ups.com...
Since you are talking about temperature, I wanted to add something
about heaters.

One catastrophic problem that can occur is that the heater thermometer...

Good advice. I've heard of a few cases of catastrophic failure of a heater
basically killing off a tank.

My approach is to use at least to small heaters instead of one larger one.
They are both set at about tha same temperature. If one fails to turn on,
the other will at least maintain the temperature at a lower than optimal
setting until I get a chance to replace it. If it fails by remaining on,
the lower power makes it more difficult for the water temperature to climb
dangerously.

I find most people use heaters that are too large. 300W may sound
impressive and therefore better than a 100W, but if the 100W is all that is
needed to maintain the temperature in a tank that is sitting in a heated
room, do you really need the extra power and the risk that goes with it?

Not too mention that the 100W will gradually increase the temp whereas the
300 W is quicker and tends to overshoot.

Robert