Keeping Your (fish tank) Cool
During summer months, overheating can be a serious problem for our aquarium fish. Thankfully there are a number of simple, cheap solutions as well as a few more reliable high-tech methods to cool your aquarium.
The trouble with overheating fish-tanksMost tropical fish will live happily in water with a temperature of 24-26C, with some preferring a few degrees either side. In a heat wave lasting a few days, aquarium temperature can rise quickly to over 30C and at this temperature many fish will start to run into trouble. At higher temperatures, oxygen is reduced in water and this is what causes many fish suffer, along with general exhaustion and discomfort. In serious cases high temperatures will cause fish deaths, or stress leading to disease.
What not to doMany fish keepers first instincts are to turn the heater off and carry out a large water change to cool the aquarium. These are in fact two of the worst things to do. Heaters have a built in thermostat and will switch themselves off when the temperature rises above of the set range, so switching off the heater will have no cooling effect. If the heater has been switched off, the water temperature could even become too cold at night, creating a greater day-night fluctuation and causing more harm to your fish.
Carrying out a big water change with cold water can lower the temperature too quickly, again causing stress to your fish and even killing filter bacteria, so should be avoided as a method of cooling. Whilst smaller water changes can be used to drop the temperature slightly, you would need to do several small changes a day to keep temperature down without causing a rapid change each time.