Struggling To Keep A Stable Temp

[saltynay]

My temps seem to rapidly rise and fall for no apparent reason. Went to bed last night only heating in the house was the tank heater at 22.5C and the tank was at 23C woke up this morn about 9ish and temps had shot upto 27C so I clicked it down one notch to 22C and turned on the lamp. Just looked behind and I am at 21C. Closest radiator is about 3-4metres from the tank, ambient temps are around 17C (reading off my pc so probably one or two degrees below that). Simple physics means that without an external heat source it shouldn't be reaching these temps and should be relatively stable possibly dropping slightly at night not rising. Anyone got any ideas?

 

[Joinerlavin]

how bigs the tank, the heater might not be strong enough to keep it at a constant temp.

 

[saltynay]

5 gallons not sure on the wattage of the heater its about 15cm long

 

[jonny_dw]

Should say on it what the wattage is, I assume being a 5 gallon most heaters around wouldnt have a problem heating that. Can I ask why you have the temperature set so low?What fish do you have?It is quite low for most tropicals.

 

[saltynay]

Endlers and amano shrimp. The endlers should be kept between 20-30 and the shrimp 22-28C. I keep the temp on the heater so low as it seems to fluctuate between 21-28 randomly whilst watching it I try and keep it around 26C by single twist up or down on the heater but would much prefer if I could just leave it to find a stable equilibrium on temps.

 

[OldMan47]

It sounds like your heater may be too big. If temperature jumps up every time the heater comes on, the heater may just be too big for the tank. You only want between 25 and 50 watts of heat in a tank that small. Those heaters are usually quite small physically because the people who make heaters know you need to fit them into a small tank.