New aquarium

[tel0004]

I have a friend who is seting up a 30 gallon fish tank. Right now it is filled, and it has a 200 watt heater. The bottom of the tank is 70 degrees, and the top is around 90. He has a penguin 170, but it is on his 10 gallon tank right now, so there is not filtration and no fish in the aquarium. What is causing the temperature difference. Is it a bad heater, or just because there is no filtration.

 

[ChicoRaton]

if there's no circulation, a thermocline like that will form. Once you get osme water movement the temp will even out

 

[Indigo]

Ugh, thermodynamics >.< But I'll give it a shot...

Hot water rises. And since there's not enough circulation to keep everything mixed you've got a hot top and a relatively cool bottom. Off the top of my head, one idea is to move the heater closer to the bottom, creating more of a convection effect. Second idea is to turn the heater off for now, until you've got better circulation. Turn it back on say 24 hours before you plan on adding fish to get the water to the proper temp.

It might be a bad heater. Might not, its hard to say. When you get the filter back, keep an eye on the temp for awhile so you don't cook your fish.

 

[Indigo]

Gah! What chico said

 

[Seaman]

you might wanna becareful, if its that hot on top but cooler on the bottom, the heater may not realize that its too hot and it will keep on heating....also a 200w heater could heat a "normal" 100g tank so that probbably doesnt help any, that its oversized for that tank.

 

[ChicoRaton]

if its that hot on top but cooler on the bottom, the heater may not realize that its too hot and it will keep on heating

yeah,that's what the water circulation is for

a 200w heater wouldn't be able to heat a 100g aquarium more than a few degrees above ambient though. I have a 200w tronic heater on my 55g and it's on more than half of the time when my room is at a slightly cooler than average temperature. 200w is slightly oversized for a 30gal, but not too bad.