Keeping An Aquarium Cool In The Hot Weather

This weather can be a problem for all sorts of pets. Fish will encounter weather/temperature fluctuations in the wild, but this will cause stress.

I also have danios, WCMM, and other temperate fish, so my sympathies are with you. My biggest problem is my axolots, which have been known to die in temperatures above 24C. Over the past few years I've picked up a few tips, especially on the axolotl forum, about keeping tanks cool.

Fill bottles with water and pop them in the freezer, or use ice packs. When frozen put them in a large ziplock bag/freezer bag, and float them in your tank water. Depending on the size of your tank, this is usually the easiest solution to a short term heat problem, and with enough bottles/packs you can rotate them and keep things cool.

Use a fan to blow across the surface of the water, which will help with evaporation. The down side with this is that lots of evaporation will start to concentrate the mineral content of your water, so evaporation should be replaced with RO.

Wet/damp towels draped over the tank, with a fan blowing onto the towel will also help.

If you are absolutely desperate, and at home all day, several water changes during the day will also help to keep things cool. Don't do huge/very cold water changes as a rapid change of temperature will also cause stress. Keep an eye on the thermometer and the fish as you lower the temperature.

Don't have your tank lights too bright, or raise them further away from the tank as well.

I ended up getting a chiller for the axolotl tank because low temperature is so critical for them. I'm not currently running a chiller on my river tank (which contains temperate fish), but it's a big tank, so doesn't heat up quickly, and I tend to go with the usual tips for keeping the room cool (closing curtains & windows on sunny side of house, etc.), along with ice packs & damp towels.

Best of luck and keep us posted.

Fill bottles with water and pop them in the freezer, or use ice packs. When frozen put them in a large ziplock bag/freezer bag, and float them in your tank water. Depending on the size of your tank, this is usually the easiest solution to a short term heat problem, and with enough bottles/packs you can rotate them and keep things cool.

Hi Littlefish,

This method could potentially cause rapid cooling of the tank water, which would not be good for the inhabitants. Factors such as water flow rate, tank size and cooling bag size would need to be considered.

JPC

Keeping the room cooler -

Keep curtains, blinds etc closed for windows which face the sun. If you are out all day this might mean leaving all the curtains/blinds closed if different windows get sun at different times.
Leave the windows shut during the day to stop warm air coming in from outside
At night, leave as many windows open as possible - obviously not a good idea for ground floor windows (open invitation to burglars)

This does work for us, going outside it's like walking into an oven compared to indoors.

I have managed to get the temperature down to 26.5 degrees using a fan on the surface of the water for a few hours yesterday. The fish seem to be really enjoying it! I do have a large airstone in my aquarium already so hopefully that should be keeping the water oxygenated. I don't have an RO filter, but the water level hasn't really gone down that much in my aquarium.

Its back up to 27.5 today but I am using the fan for an hour or so this morning to hopefully get it down a degree before I go to work.

Maybe I'm lucky to live in the north. My main tank is currently at 24.5 deg, though the thermometer in the betta's tank has come adrift and is at the back of the tank so I've no idea yet for that one.
The house is in semi darkness; the windows all face north or south so at the moment all the south facing ones have the curtains, with thermal linings, shut. Late afternoon, we draw all the north facing curtains.

If you have fluorescent lights they get quite hot when they are on. Don't have them on today as they'll help heat the water. LEDs aren't as bad, but if those get warm leave them off too. It's only for a day or two in this country, plants won't come to harm during that length of time.

How have all your fish managed today? I have to confess that my main tank only went up 1 degree above normal.

But in the south, you've had it hot with the hottest July day on record being reached in Cambridge @Littlefish

Wow that is hot... the car was absolutely boiling tonight for my journey home... I had to run the aircon in the car for a while before in could face getting in it... my 6 week old is not a happy bunny. The storms and rain have cooled things down significantly now though and the next few days are set to be much cooler.

But in the south, you've had it hot with the hottest July day on record being reached in Cambridge @Littlefish

Apparently 38.1 here in Cambridge yesterday. I spent the whole day doing water changes on the tanks to get temperatures to around 25C. Went outside to throw some waste water into the garden and thought I was going to melt. I felt very sorry for anyone dealing with going to work in that sort of heat.

Everything seems so much better this morning. 

I had the same issue with my tanks today, although it was quite reassuring to see condensation on the inside of the mudskippers tanks rather than on the outside of the axolotl tank. 

Hi, looks like lotsa members concerned over recent 'heatwave' - wasn' quite as severe as forecast down here in the SW.. but prompted me to 'investigate my options'.. I felt the water change with cooler water was perhaps the quickest and easiest fix, even if it had to be repeated, but not to 'do it blind'.. a little bit of maths first - sorta planning      - example:  tank volume 60L    current tank temp 80F / 27C   proposed change 10L    input (tap) water temp 64F / 18C.. so, we gonna have 50L x 80F = 4000 + 10L x 64F = 640.. so, after water change we shud have 4000 + 640 = 4640 divided by 60L for new tank temp, i.e. 4640 / 60 = 77.3 F.. not bad - a 3 degF drop for one bowl of water.. I believe I tried that last week in my 350L cichi tank, just to check if my math was valid, and it seemed to work..  I  believe, even in that 60L tank, with just a 10L water change, the temperature drop wud take a few minutes and not be too much shock to the fish.. for bigger tanks, using 'more bowls' wud be even slower, so hopefully not a prob.. perhaps Littlefish and Sue can validate my 'math' assumptions.. either the 'theory' or in practice.. I believe it works,  and is a 'free' easy fix...