How Do I Cool A Tank

[daveg6529]

This isn't much of an Emergency but it could lead to one.
I have a small 40ltr tank with a few Platys (6).
Unusually for the UK we have a bit of a summer at the moment and I have noticed that the temperature of my tank rose from 25 degrees C (77F) to 31C (88F) yesterday evening. I removed some water 50% and topped it up with water @ 25C, this brought the temp down. Today the same thing occurred - I repeated yesterdays solution.
Tomorrow I don't get back from work until midnight so I suppose my question is
How will this affect my fish?
&
Have I done the right thing?
The tank is not in sunlight and is placed in the coolest area of the coolest room in the house.
I don't want to buy a cooler as we get so few days of sun here (London, UK).
 
The tank has been running for over a year and the fish appear to be fine without any ill effects (but I don't know enough to be sure).
 

Sorry about the little picture. I don't know how it appeared on my post.

 

[fluttermoth]

You shouldn't need to worry.
 
Nearly all our tropical fish can cope with higher tempeatures, as long as the change happens gradually and it's not for extended periods of time.
 
Your main issue is going to be that warm water holds less dissolved oxygen than cold, so make sure your have enough aeration (add extra, if you have an air pump available) and that your filter is really disturbing the water surface. Raising the filter outlet, or lowering the water level a few inches, might help in that area.

 

[daveg6529]

Thanks I'll drop the water level to allow the pump to agitate the water more.

How long could they stand a raised temp?

 

[fluttermoth]

I'm not 100% sure on that, but it would be a matter of days, given enough extra oxygen, and don't forget, your tanks will drop a little bit at night/early mornings.

 

[TwoTankAmin]

Put a fan set to blow across the front of the tank. You can do this across the top, but I would want to remove the lid then. This can be an issue if one has fish that jump. Remember not to run the lights.

 

[Blondielovesfish]

You can also put several frozen bottles of water in your tank. They will only last about 3-5 hours but its better than nothing!

 

[DoubleDutch]

 

Put a fan set to blow across the front of the tank. You can do this across the top, but I would want to remove the lid then. This can be an issue if one has fish that jump. Remember not to run the lights.

 
The only way to cool down is the veperation of water (that takes energy / heat from a tank). Putting a fan to blow across the front of your tank won't work. It's the windchill that cools us humans down (veperation as well)but it won't cool down objects as a tank. Blowing over de surface is another thing : that will stimulate veperation = cooling down as I said.

Unplug your heather so temps maybe an drop a little further than the heather is set. Fish can better take higher temps gradually raised than lower temps dropped in a short period of time. So I wouldn't use the bottles as well.
Cheers Aad

 

[TwoTankAmin]

If you put your hand against the glass of tank that is clearly a different temperature than the surrounding air, you can feel the difference.
 
If you have ever had a filter seize up, you know how warm the water is inside when you discover it. If the tank is warmer than the surrounding air, which is likely if you have equipment running since this equipment generates heat which will get transferred via the flow from the filter into a tank, pushing air across the front glass will be a help in moving the heat from the surface of the tank glass and dissipating it. You are basically facilitating this form of heat exchange with a fan.
 
While you are using the same fan to do this that you would use to facilitate heat transfer via evaporation, the method of the transfer differs. Of course blowing across the front of the tank will not have any cooling effect when the tank is cooler than the surrounding air. But when it isn't, the large surface area of the glass, even though not the best heat conductor, provides a big enough surface to help.
 
It also matters how the tank is being heated. If you put identical tanks outside, one in the shade and the other in direct sun, the latter will get hotter than the surrounding air. The one in the shade should reach the ambient temp. But it is likely the filter etc., which adds more heat, will cause the tank to get over the ambient air temp.
 
Any motor used in relation to a tank- filters, power heads, air pumps, lights etc. all generate heat which heat the water. While we can leave the lights off, leaving the other things off is not an option, especially when its very hot and the oxygen level in the water tends to be lower.