Things You Should Know About Freshwater Aquarium Temperature

What is the Best Temperature?

So you’ve setup your tank, the filter is working and you’ve checked the water ph. Using the heater thermostat you now need to set your freshwater aquarium temperature.   What should that temperature be?   Most freshwater aquariums do best somewhere between 73 and 82 degrees Fahrenheit (23 to 28 Celsius).   Depending on whether you live in Alaska or LA will dictate the best freshwater aquarium temperature.    The reason is that you want to avoid water temperature fluctuations as much as possible.   So in a cool climate 75 degrees Fahrenheit is favourite and in a warm climate 80 degrees Fahrenheit would be best.   This has the effect of minimising the impact of ambient temperature changes on the freshwater aquarium temperature.

It is important that you are aware of the fact that the water cannot hold so much oxygen the higher its temperature so more aeration is needed.   As it happens acrylic is a much better insulator than glass so temperature fluctuations will be smaller in acrylic tanks, a fairly tight fitting lid also helps.

To a large extent the actual freshwater aquarium temperature that you set is not too important, it is sudden changes in water temperature that will kill fish.      Rapid temperature rises or falls really stress out you fish making them prone to disease and can kill them.   Sudden freshwater aquarium temperature changes usually bring on the ‘shakes’ or ‘shimmies’, ‘Ichthyophthirius’ (ick), fungus or a general decline downhill.

What Size Heater?

There are two things upon which the required heater wattage depends, how much water is to be heated and the temperature rise required.   A good rule of thumb is to calculate on the basis of requiring 2 watts to raise each gallon of water through 5 degrees.   Large tanks with high temperature differentials may need two heaters.   If so they should be placed at each end of the aquarium.

You should not use a higher wattage heater than as calculated by the above formula.   There are a couple of very good reasons for this, number one you do not want the heater as it turns on and off with the thermostat to cause rapid temperature rises and number two, if the thermostat fails you do not want your fish to fry.

What kinds of heaters are there?

There are three kinds of heater, all work well.

1.   Immersible heaters.    These are the most common mainly because they are easily found and inexpensive.    They hang onto the back or side of the aquarium, dangling into the water.   A temperature control knob is kept above the water.   Their downside is that they can be considered an eyesore, a lot of people prefer the heater to be hidden.

2.   Submersible heaters.   As the name suggests these are completely immersed in the aquarium water.   The good thing about them is that they can be hidden behind rocks and plants.   These heaters are very reliable and keep a constant tank temperature with ease.   They’re easy to use, slim–so that you don’t notice them as much, and relatively inexpensive although they generally cost more than the immersible variety.

3.   Filter heaters.   These are a really good option because they keep the freshwater aquarium temperature even throughout the tank.   As the water passes through a filter it is heated.   They are filter units as well consequently they are the most expensive type of heater.   The big plus of this type of heater is that it is outside your aquarium, so it doesn’t take up space inside and you don’t see it at all!

Don’t Forget a Themometer!

One final word, make sure you have a good thermometer in your tank. Before use chack that its calibrations are correct. Every day after that you should regularly check the reading. The best time is to glance at it as you feed your fish. This way you will know about any freshwater aquarium temperature problems before they can have a lasting affect on the wellbeing of your fish.

Conclusion

So there you are.   Your freshwater aquarium temperature should be closely controlled by heater and thermostat, the actual set temperature depends upon where you live.   Keeping temperature fluctuations to a minimum is much more important than what you select as your freshwater aquarium temperature.