Heater question

[muddydogs]

In my current 10 g tank I have a 100 watt tetra wisper heater. When I got the heater it said for tanks between 5 and 15 gallons, I think. My current problem is I have the heater turned almost all the way up but still have problems keeping my tank at a constat temp. The temp will swing from 68 to 73 degrees. For a little home background, I keep my house at 64 degrees from 7am to 3pm then the temp is at 68 degrees from 3pm to 10pm where it agian falls to 64 degrees for the night. Out side temp has not broke freezing in a few weeks during the day and night temps are around 10 degrees. My thinking was the heater should be able to keep the temp constant with the 4 degree temp swing in the house but the aquarium heater dosn't seam to be doing this. So is something wrong with my heater or am I going to have to keep the house temp more constant and pay the gas company more to keep these little fishys comfortable?

Thanks Jim S.

[CroW]

I've found that most manufactures tend to overestimate the gallon size that their heaters can handle, I always go one step up from whatever is recommended.
Also, I've seen that different heaters have different thermostatic mechanisms.

The heater in my 55 keeps the water at 80*F constantly, I've never seen it vary by more than 1*F. It has ceramic around the heating coils and not sure what type of thermostat it has.
However, the Whisper heater in my 29 shows a 2-3*F swing depending on room temp, this heater does not have ceramic and uses a small bi-metallic strip as its thermostat.

So, you might look at a different brand/type of heater..

[DUSTIN323]

You might wanna go buy a new heater because with 100 watts it should definetaley be keeping it warm. Go buy a quality one in my 10g I used to have a Marineland Neptune 50 watt but it didn't work that great but adequate so I switched to a 50watt Aquarium Systems heater I had sitting around and it works good.

[mousey]

also a number of the better heaters say on the package that they are tested for acuracy in a 70 degree room.
mousey