Why do tanks get hotter than the titanium heater setpoint?

[BilboB]

I have 2 titanium heaters - one set at 78 degrees and a backup set at 76 degrees. My tank was 78 degrees for months, but then I noticed it was 80 degrees. I lowered both heater setpoints 2 degrees, but the tank is still 80 degrees. Any reason why?

 

[Mebbid]

What brand and what are you using to control the temperature?

It's common that the heat will swing a little above and below the heater setpoint.

 

[commod0re]

In short because they use a style of heater control called “bang-bang” which is called that because it bangs the heater on to 100% and then off to 0%. Bang-bang is generally used with slower heater circuitry like relays. Electronically the circuitry is simple and inexpensive but a downside is that it tends to overshoot the set point, the temperature will float just above and below whatever the set point is

A heater with proportional control or a full PID can be much more stable

 

[BilboB]

I figured it out - the elevated temperature was due to a pump I had in my tank (I don't have a sump, so I run my UV using an in-tank pump). I turned off the pump overnight and the tank temperature matched the highest-set heater.

 

[formallydehyde]

I figured it out - the elevated temperature was due to a pump I had in my tank (I don't have a sump, so I run my UV using an in-tank pump). I turned off the pump overnight and the tank temperature matched the highest-set heater.

Even without a pump (which pumps themselves always generate heat to some extent), a UV-C bulb will get pretty hot. They need to get to a certain temperature inside to even run.

 

[BilboB]

So it could be the pump or the bulb, great.

 

[W31Olds]

My heater never runs and my Tank is still at 79 degrees. All the Pumps, lights, and my UV pretty much make a heater unnecessary.

 

[Gumbies R Us]

Just because you set your heater to be one thing doesn't mean your tank will be that temperature. Our tanks have a lot of electrical equipment running on them, and all of that equipment generates heat.

 

[Paul B]

Remember, anything made for a hobbyist is not a scientific instrument like they use on Space Shuttles. The thing was probably made on a back road in China or Korea and was never tested. As long as it gets hot, it is fine.