question about heater size

[darkslayer414]

hey all...i just bought a new 20g tank and the only heaters i have left are a 300 watt heater and a 200 watt heater. if i keep the 200 watt heater in the 20g tank is that going to be a problem or should i go buy a 75 watt heater made for a 20g tank?

 

[flower]

Originally Posted by darkslayer414
http:///forum/post/3008602
hey all...i just bought a new 20g tank and the only heaters i have left are a 300 watt heater and a 200 watt heater. if i keep the 200 watt heater in the 20g tank is that going to be a problem or should i go buy a 75 watt heater made for a 20g tank?
I really don't think there is a problem...As I understand it a heater is only going to heat until a temp is reached. The bigger heaters don't have to work as hard and they are longer to allow as much heat as possible for water to flow over.
So if you set your heater on say 78 in won't come on until it needs to reach 78 in the water.

 

[salt210]

yeah if you use a bigger heater it will not have to work as hard to heat the tank

 

[sickboy]

Yep, what they said....

 

[natclanwy]

The problem comes when you have a heater "stick on" a 75w heater will cause a slow rise in temp giving you time to catch it. A 200w or 300w heater can cook the tank in few hours.

 

[salt210]

good point.

 

[scsinet]

Originally Posted by salt210
http:///forum/post/3013721
good point.

I've also seen personally many times a situation where a too-large heater overheats the water. I've never been able to fully explain it.
The other thing to consider is that a heater that is significantly oversizes, like yours will cycle very rapidly, ergo causing rapid temperature swings in the tank. If it cuts on at 78 and off at 80, that 2 degree swing can happen fast enough to stress the animals.
For what heaters cost, I'd buy one that is appropriately sized.

 

[bill109]

i used a 100 W in my 20 long..
not sure if your looking to buy a new heater or not but you could get away with either a 75 or 100.