Heaters.....

[SuperColey1]

In quite a lot of tests digital ones come out worse than standard mercury and glass. I also use a Wilko one and can't see the point of paying out any more than the 99p they cost for one.

The only reason for a mercury thermometer showing a result as far out as 2ºC is if the card/plastic with the numbers on is not in the right position. Much like the print/markings on the dial of a heater being slightly off!!!

I doubt in average tanks the temperature is that much different anywhere unless the filter is quite literally underpowered for the tank. It would need to be pretty large for there to be too much variation.

Even so water has a habit of equalling itself out filter or not!!! Remember the hot rising to the top and cold sinking to the bottom experiments at school? simple theories but very true.

Of course water next to the heater will be slightly hotter than the rest of the tank.

With the external heaters though they are actually putting heated water into the tank via the filter output so the heated water is instantly being pushed around the tank via the filters circulation.

Have to say to the person with the pics of thermometer and heater above. that is a pretty hot tank? Do you have discus in there?

AC

 

[keenonfish]

Is it not the average tank temperature that we WANT to measure rather than the temperature of the particular peice of water that happens to be flowing past that fraction of a second?
Certainly after a water change I can watch this thermometer drop as the fresh water goes in, and then gradually climb over a few hours as the water heats again, (of course I don't know how much dealy is involved, but testing it in a cup of water it seems to react within a few seconds of change).

Even digital therms are not anything like that quick to measure but yes, I think I pointed out in my post that average is the important factor. I will say that the alcohol based thermometers are visibly going to change much quicker with a higher temperature differential and much slower of a change over a couple of degrees so there will always be lag here.

 

[keenonfish]

Problem with Digital thermometers is that they are so common & cheap these days it is very hard to know how accurate they are. And just like all things digital, just because it uses the D word it doesn't automatically mean it is better quality (hehe DAB radio is a super example here!).

I know I have some pretty nice thermometers as I was a catering engineer and had my stuff calibrated to high standards (think they used a black body source).

There are some fairly accurate methods to test at home but better really to have it done properly.

 

[smegforbrains]

(think they used a black body source).

It was probably a dry block pot

 

[Schmill]

Have to say to the person with the pics of thermometer and heater above. that is a pretty hot tank? Do you have discus in there?

AC

Sorry for the confusion, I normally put a note under those pictures and seems I forgot, (going to edit now ).
I don't have discuss in there, just water and gravel, and ornaments. I'm just at the end of my fishless cycle (which likes an elevated temp.), so that will be being dropped back down to a more reasonable 24 in the next day or so
10 / 10 for observation though!

 

[raptorrex]

It seems that no matter what heater i have in my tank at whatever setting,the temp will always rise to about 26C.I'm not that fussed ,as its a steady 26 ,but i'm curious as to why?Anybody?

as the above, seems to be the OP's basic question. we seem to have gone off track going into the mechanics of thermostats and the like.

so does anybody else find that the setting (whatever it is) on your heater have no effect at all?

 

[SuperColey1]

To answer those questions we need to know some things:

What is the ambient temperature of the room the tank is in?
Is there anything like a UV in the tank or inline?
Is this 26ºC temperature constant night and day?

What I am suggesting is that if the room the tank is in is 26ºC then of course the tank water is likely to remain at the same temperature.

If using a UV this will also heat up the water.

If the temperature is 26ºC all day and the ambient temp is 22ºC then it could be the lights heating the water so does it drop overnight with the lights off?

In answer to the original question I have never had a heater that heated to a constant temperature no matter where I set it but as stated I have had heaters that I set to a different temperature to get the temperature I want.

I have however had tanks that stay at the same temperature no matter how much I lower the heater temperature down due to using UV and also the light effects. The heater however was not heating. It was clicking on, seeing the temp was OK and clicking off within seconds.

AC

 

[keenonfish]

Well reading the Op's first post again I can't see how the situation is possible, given that he has tried different heaters AND when he removed the heater the water drops back down to ambient room temperature. Given that the heater is coming on means there are temperature fluctuations. If it was only one heater I would have said the dial was no longer mechanically connected to the stat but obviously this isn't the case..

Obviously there is something strange going on

OP are you sure you are not switching other gear as posted above (i.e. UV etc) when you switch the heater?

OR maybe you have one knackered heater and when you replaced you haven't thoroughly tested the others before assuming they were faulty? I once tried a heater that had been lying around for a while the temperature just didn't want to settle down near the indicated temperature at all (seemed to constantly creep up, turn off, creep up etc..) but I was impatient and constantly messed with it then after a week it settled down and started working correctly.

 

[raptorrex]

Well reading the Op's first post again I can't see how the situation is possible, given that he has tried different heaters AND when he removed the heater the water drops back down to ambient room temperature. Given that the heater is coming on means there are temperature fluctuations. If it was only one heater I would have said the dial was no longer mechanically connected to the stat but obviously this isn't the case..

Obviously there is something strange going on

OP are you sure you are not switching other gear as posted above (i.e. UV etc) when you switch the heater?

OR maybe you have one knackered heater and when you replaced you haven't thoroughly tested the others before assuming they were faulty? I once tried a heater that had been lying around for a while the temperature just didn't want to settle down near the indicated temperature at all (seemed to constantly creep up, turn off, creep up etc..) but I was impatient and constantly messed with it then after a week it settled down and started working correctly.

that's why i reiterated the question. it just didn't seem possible. well not if everything was working as it should.

 

[jimmyringo]

What is the ambient temperature of the room the tank is in?
What I am suggesting is that if the room the tank is in is 26ºC then of course the tank water is likely to remain at the same temperature.

Room temp is about 22c(as stated in original post)

Is there anything like a UV in the tank or inline?


If using a UV this will also heat up the water.

No,don't have a UV.

If the temperature is 26ºC all day and the ambient temp is 22ºC then it could be the lights heating the water so does it drop overnight with the lights off?

Temp is pretty much constant,lights on or off.

 

[raptorrex]

What is the ambient temperature of the room the tank is in?
What I am suggesting is that if the room the tank is in is 26ºC then of course the tank water is likely to remain at the same temperature.

Room temp is about 22c(as stated in original post)

Is there anything like a UV in the tank or inline?


If using a UV this will also heat up the water.

No,don't have a UV.

If the temperature is 26ºC all day and the ambient temp is 22ºC then it could be the lights heating the water so does it drop overnight with the lights off?

Temp is pretty much constant,lights on or off.

so this happens whatever heater and whatever settings you use?

 

[jimmyringo]

Pretty much.Ive only ever used 2 heaters.The first one was in for a couple of years set to 22c and the temp was always 26c.i put a new one in about 3 months ago ,set it to 24c and it gave me a temp of 26c.So i dropped it to 22C for a few days and then down to 20 and finally 18 without the temp changing.Its sat there for a couple of months now,and the temp has always been 26.I turned it off once just to see and the temp dropped to about 22c.
As i say ,a constant 26 is grand for my fish,i'm more curious than anything.

 

[SuperColey1]

Got me foxed then. Can't understand why 2 different heaters would have this same problem.

What size tank do you have and what is the wattage of each heater you used?

AC

 

[smegforbrains]

Is the tank anywhere near a radiator or heat duct?


Do the heaters actually operate at all? Do you see the neon indicator light up?

 

[raptorrex]

Got me foxed then. Can't understand why 2 different heaters would have this same problem.


AC

Ditto