Keeping An Aquarium Cool In The Hot Weather

Apparently we got a new high temperature record in Cambridge last week, but I'll admit that the only planning I did was along the lines of "I'm going to need a lot of cold water", rather than calculating anything accurately.

I tend to just keep an eye on the thermometers while doing cold water changes, and due to the tank water volumes involved I'm quite hard pushed to drop the temperatures by 2C in less than 30 minutes on my largest tanks, even using a combination of cold water and frozen water bottles.

The smallest tanks are 60L, and I used 10L cold water over a period of around 15 minutes, which drops the temperature by just over 2C.

I understand that the use of frozen water bottles is generally frowned upon. Nobody wants to stress their fish with a rapid, localised temperature drop, or have a plec decide to attach itself to anything that's frozen. The tanks I use them in both use FX external filters, so I feel that the cooler water is moved through the tank quickly enough not to cause cold spots, and I usually only use them in an emergency, and in conjunction with water changes.

Perhaps the best part of doing a cool water change during a heatwave, apart from lowering the temperature, is that you can also claim it as part of your weekly routine tank maintenance.   

Actually, the best part of any of the cool water changes I did last Thursday was when I spilled the water on myself.