Heater not working well in tank

[H20lover99]

I had to separate my cichlid from another cichlid awhile back. I have him in a 10 gallon tank right now in a room that's not heated well. At 1st I was using the heater that came with the 10 gallon but it wasnt working well enough. So I got him a 20 gallon tank heater that is now in the 10 gallon tank. I have noticed even tho I have the heater turned to 85 degrees the temperature is still 70 degrees. I have tried the heater in my main tank and it works to liking. I also have 2 temperature readings in this other tank to make sure of accuracy. This other tank the top dosent fit correct either so I just kinda lay it on top. Now I wont normally have it set at 85 degrees but I turned it up so it would at least get to 75. But no go. Anyone think i should try to put another heater in there. I have also noticed that the heater in there now never turns off. I think its attempting to get there just never does.

 

[speakerman3]

A heater can raise the temperature 15 or so degrees above the ambient temperature when you have 2-5 watts per gallon. Heaters can be insufficient for a given tank size and room temperature, but they can also start heating and not turn off. As a result of this danger, it is better to have two lower-wattage heaters in a bigger tank than one high-powered heater. That also protects against one heater failing and letting the tank get too cold.

In your case, you have one heater that isn't heating your tank sufficiently to counter the amount of water and room temperature even though it is a higher-wattage than is normally required. Assuming that the current heater is working properly, you could add cardboard or foam on three sides of the tank to insulate it or add a second heater of 5 watts per gallon, or do both.

Good luck.