Summer is coming and although it may get warm in your house, you need to think of your fish and what their range of water temperature should be for their safety.
You will have to do some reading and asking questions of the right people in order to know this correct water temperature range for the specific type of fishes that you have.
Some people may enjoy just opening their windows in the house to get some air, but as we get into the month of June and temperatures outside heat up, if you don't have your air temperature controlled with an air conditioner, for example, your air temperature may become so high that it is effecting your aquarium water temperature and causing it to be too high. Your fish will become sick and suffer and die if you do not pay attention to this detail.
Even if you have clean water and the water is pH balanced and you have tested your aquarium water with an aquarium water test kit and you have done everything else right, if you do not pay attention to this one thing, you will have an aquarium disaster on your hands.
Know your fish - know their breed and check reference information on the subject of that specific type of fish and you will find the water temperature in which your fish will thrive and live happily.
Remember to put your aquarium in an area in your house away from direct sunlight so that, for one thing, it will not heat up too much.
Also, keep your aquarium away from hot drafts of air.
It's unlikely that you will need your water heater for your aquarium.
Be sure to use your aquarium thermometer.
It is a good idea to keep your air in your house at a reasonably cool temperature in the summer not only for the human inhabitants, but also for the fishy inhabitants as well. Just as we take care of our own health, we must also consider the health of all our pets, including our wet ones - the beautiful fish in your aquarium. They give us many hours of enjoyment and fun and relaxation and are a great way to teach our kids about nature.