Room Temperature

[fishwatcher]

How much does the room temperature affect the water temp in a tank that has a heater? It seems that my tanks are never as warm in the winter as they are in the summer, even with the heaters set the same (or even a little higher). How much of a difference is considered normal?

 

[BigC]

I space heated my fish-house (3kw fans) I had three tiers of tanks, the room temp was around 80'f and the top tanks came in around 74'F and the bottom teir around 72'F.
If thats any use to you
Regards
BigC

 

[Bignose]

Well, you have to remember nature always strives toward equilibrium. If the tank is warmer than the surrounding air, the tank will give up heat to the surrounding air. Hotter objects will always give up heat to cooler objects until equilibrium is reached. In almost every case, equilibrium means everything is the same temperature. There are special cases if there are heat sources or sinks, but basically, it means heat will always flow to try to bring everything to the same temperature.

How much room temperature affects the tank is a question of how efficient the heat transfer is. There are 3 methods of heat transfer, conduction, convection, and radiation. Radiation isn't going to be a very large part at all (though it is non-zero, everything radiates at least a little bit!), it becomes a question of conduction and convection. Which mechanism dominates depends on a lot of factors -- how stagnant is the air near the tank? How big is the temperature gradient? Because, if the temperate gradient between the tank and the air is large, the air will get heated up, it will then rise, causing convection -- this is known as natural convection. This is as opposed to forced convection, if the tank is next to a fan or a vent, for example. The amount of heat transfer varies depending on which mechanism is at work, and it is most likely in total a combination of all three mechanisms. We also have to look at the inside of the tank. Water is much denser than air, so conduction becomes a much more important mechanism for moving heat -- but the filter is making forced convection and the water around the heater itself will undergo natural convection.

So, you have to look at each of the following steps. 1) How efficient is the heat transfer from the heater to the water 2) The heat transfer from the water to the tank material (and it matters a lot if it is glass or acrylic or something else) 3) The heat transfer through the tank material 4) the heat transfer from the outside of the tank to room 5) the heat transfer from the top of the tank

So, it is not an easy process. However, in all cases, the larger the temperature difference between the tank and the air, the larger the heat transfer will be.

 

[cbr6fs]

Great post,

This is something that was worrying me, last summer we saw 48c, without the AC on the living room easily reaches over 34c.

Leaving the AC on 24/7 is really not an option, so i was/am really worried about how the temps are going to affect the tank water temp.
Importantly i think, of all the LFS's i've visited the past few weeks i've not seen 1 cooler for sale yet, so it can't be THAT much of a problem.

Be interesting to hear from people how the ambient temp affects the water temp though.



Cheers
Mark

 

[mark.w.jones]

Many fish keepers in hot countries have to invest in a water cooler for the summer months in order to keep their water temp. down. No worry of that ever happening in the UK thou.

 

[fishwatcher]

Hhmmm... interesting.
I have one tank I'm a little concerned with, bc the cooler water can cause respiratory infections, but for the most part all of the fish are ok at 72-74 degrees.
I was hoping there was a way to make the heater stay on longer so that it would warm the water up more, but I guess it just isn't designed to do that.

 

[cbr6fs]

I'm very new to this hobby so please take my advice in that context.

But if a heater is set to say 24c it should turn on at sat 23c and off at 25c so maintaining a constant average of 24c.

It should make no difference if the air is cooler of warmer, if the ambient temp is high enough to raise the water temp over the off limit (say 25c) then the heater should never come on.
Likewise if you fill your tank with cold water the heater should stay on till it's off temp is reached (25c)



Sounds to me as though either your thermometer or your heater is knackered, as thermometers are a lot cheaper than heaters i'd say buy a new thermometer first.


Just as a side note.
I have 2 thermometers in my tank, both exactly the same brand model etc.
1 was reading 26c ther other 24c, as my tank is only 120l i thought this odd, so i swapped them around.
Yep you guessed it, they both still read exactly the same temp


Hope that helps.



Cheers
Mark

 

[5teady_2012]

Just as a side note.
I have 2 thermometers in my tank, both exactly the same brand model etc.
1 was reading 26c ther other 24c, as my tank is only 120l i thought this odd, so i swapped them around.
Yep you guessed it, they both still read exactly the same temp


Hope that helps.



Cheers
Mark

Same happened to me.

 

[cbr6fs]

More of a q question to the experienced guys than a statement.


But from what i've read so far many of the recommended leaner fish have a temp band of around 4c as optimal.
So as long as your within that range surely it's more important to keep a consistent temp rather than worry if it's a couple of degrees C off?


I guess the exception to this would be if you have several species in your tank, it's unlikely that they will all have the same ideal temp range, so your ideal range would be where all the fishes ideal temps overlap, which would make that temp sweet spot a lot smaller.




Cheers
Mark

 

[Bignose]

Hhmmm... interesting.
I have one tank I'm a little concerned with, bc the cooler water can cause respiratory infections, but for the most part all of the fish are ok at 72-74 degrees.
I was hoping there was a way to make the heater stay on longer so that it would warm the water up more, but I guess it just isn't designed to do that.

"respiratory infections" ? Like infections of their gills? I've never heard of that one before. You do realize that the vast, vast majority of fish don't have lungs, right?

If the tank is cold, turn up the heater. I've found that the numbers on the heater itself and the actual temperature aren't very closely related at all. If one heater isn't enough, get a second one.

edited: replaced "gills" with "lungs"in the first line of my replay -- of course fish have gills silly!

 

[fishwatcher]

Sorry, Bignose, the tank I'm most concerned with is a turtle tank, hence the respiratory infection possibility.
I apologize for the confusion!
Mark, that is exactly what I thought heaters should do, but most of mine do not. They are all fairly new, too, no more than a year or old. All good brands, but each one a different brand (I buy them by what is on sale at the time!). I have both the stick on and the floating glass thermometers and they all have been reading pretty much the same temp.
I don't know what to do, as I really can't afford new heaters for each tank (I have 6).
Maybe the heaters are just turning off to keep themselves from burning up? It is, on average, about 63 it the day and 59 at night.

 

[Bignose]

Well, that makes a lot more sense. (about the turtle tank that is.) Next time when posting in the tropical fish chit chat area, it'd probably be best to state that up front. There is a subforum for "Invertebrates, Amphibians & Aquatic Reptiles Forum," maybe you should ask there? Otherwise, like I said, I'd get an extra heater -- the benefit there besides keeping the tank warmer overall is that if one should break, the temperature won't drop as the other should be able to pick up the slack until you get a replacement for the broken one.

 

[cbr6fs]

The chances of 1 heater not working well is great, the chances of 6 heaters from different manufacturers all having exactly the same problem are none at all in my book.

Are the heaters up to the job, what i mean is is the heating output suitable for the tank size?
A 50w heaters would really struggle to heat a large tank.

If you maybe list the tank sizes and heaters in each?


I really don't know how the heaters operate, from looking at mine it seems to be way to simple electronically wise to have any sort of timer.
I'd bet money that the cheaper simpler heaters just stay on till the shutoff temp is reached, but you'd really have to email the manufacturers to be sure.

To be honest 59f to 63f (15c to 17c) aren't that low, my living room (where my tank is located) drops to 16c if we're out and don't have the heating on.


I'm really at a loss for any other advice, if your tanks are out of sight for most of the day you could try wrapping the tanks in some form of insulation see if that makes any difference.
But as i said earlier as far as i'm concerned the heaters don't really care what the outside temp is.


Cheers
Mark

 

[fishwatcher]

The 2 29g have 150w, the twenty (turtle) has a 50w (I know it's alittle small, but I thought it would be ok since it's only about 15-16g of water), and the tens have 50w.
I'll just have to tinker around and see what I can discover, I think.

 

[Miss Wiggle]

But from what i've read so far many of the recommended leaner fish have a temp band of around 4c as optimal.
So as long as your within that range surely it's more important to keep a consistent temp rather than worry if it's a couple of degrees C off?

to an extent this is true. I've heard of this done with marine tanks particularly, because corals are often more sensitive to the high temps than tropical fish are.

So you gradually acclimatise the corals to a temperature of just 1/2oC above ideal, then when the hot weather hits and the tank inevitably warms up a bit then there’s not such a big varience and the corals cope with it better.