Temp. stable?

[Mazdaman]

The only problem I've been having with the new tank is getting my temp. stable. The tank was around 81 at intial setup. It slowly has been dropping but never lower than 76.3. I would like my temp to be around 78.5. My problem ism that i've tried the heater twice. I wait 'till the temp drops to that 76 number and then plug in the heater which is set at 78. The tank raises to like 79 or even a little higher. I remember back when I setup my 20 [acronym:c00c266e92="Gallon"]gal[/acronym:c00c266e92] the inst. said the turn on the heater once the tank was roughly 4 degrees cooler than what you wanted. Doesn't seem to be working for me. It is a jager 200w heater. I have two therm. in the tank, one is a digi and reading at one end and the other is just a normal one at the other end. They read the same temp all the time.

Any ideas or suggestions? Could I just need to turn the dial down 1 deg and make up for the difference or what? Thanks

[BrianNY]

Ebo Jagers are usually very reliable heaters. I get the temp about 1 degree higher than where I want to keep it and then back the dial down ever so slightly until the light goes off.

[ChileRelleno]

What size tank?
What wattage heater?
Temp difference between tank and ambient room temp?
Position of heater and water circulation?
Powerhead?
Average 4-5 watts per gallon for a 5-10'F between water and room temp.
Heater should ideally be placed low in the tank with good circulation to prevent uneven heating/cooling, a powerhead is good for water circulation in the lower parts of a tank.
Two smaller heaters are sometimes preferred to one larger, especially in a longer tank. Also if one malfunctions there is less chance of cooked fish before you notice the problem.