Over heating with oversized heater?

Jeffreypang911

This is my situation. I have a new 150W heater. It is rated for 40+ Gallons. I have a 33 gallon tank. I could have gotten a 100W and it would have worked fine.

I also have a thermometer that is very very old. it is one of the ones that sit/float in the tank though (the glass ones).

My thermometer is reading 82F when my heater is at 22-24C (73-75F).

Which one should I trust?

Is the over sized heater heating my tank too much? Ive been trusting the thermometer a lot lately so.

Thanks a lot,
Jeff

Fishin Pole

You probably did the correct thing buying the higher wattage heater.....When it does kick on it wont have to heat as long as a smaller heater wattage heater would have to, thus saving you electric and extending the life of the heater....As cheap as thermometers are, i would buy another one and compare the readings you get............See where the temp is and adjust your heater back a little.......Dont do large changes all at once, just turn the heater back a little and wait a few hours and check temp and adjust again till you get your desired temp.........I have 7 tanks at the present and i bought 10 thermometers and tested them all in the same tank.........9 of the 10 gave me the same reading and the 10th was one degree warmer.......I now know all my thermometers are at the same level.......These are the really cheap floating type Wal-Mart thermometers and i havent had any issues with them....

Tyyrlym

The dial on top of your heater is meaningless. Just use it as a reference to be sure if you're turning it up or down. Go by your thermometer.

jeaninel

Yep, I've found that the dial on the heater is often way off. The glass floating thermometers have always done me well.

Oldman47

If you want to know whether to trust the thermometer, take it out of the tank, dry it off and lay it on the kitchen table for 30 minutes. By then it should show the same temperature as the air in the kitchen. If it is off, splurge and get a new one for about the price of a light bulb.