Causes for Aquarium Heater Too Hot (4 Tips and Solutions)

When you have an aquarium, one thing that is crucial for the health of your fish is the water temperature. If this falls on the colder side of the ideal, fish will become sluggish and can suffer if you don’t warm it up.

One of the worst things that can happen is when you have a problem, and you are unaware of it. Water temperatures that are too warm, and can have a detrimental impact on your fish, as much if not more than cooler water.

Unless you live in a very hot environment, there is usually one reason this happens.

Is the aquarium heater too hot? Here’s what to do:

Once you see your heater is becoming too hot and your water temperatures are rising, you do need to stop the water heating up too much. Second, to this, you will need to cool your water back to the ideal temperature, although you can’t do this too quickly, or you will stress and shock your fish.

If your heater is faulty, all you can do is purchase a new one. Here, we will look at what you can do to cool your water back to the ideal temperatures for the safety of your fish.

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Tank Temperatures Vs. Temps in the Wild

Unless you have had your aquarium for a while, you will need to understand how temperatures affect your fish. Fish are cold-blooded, so their bodies follow the surrounding temperatures, unlike humans whose bodies will adapt for the varying temperatures.

In the wild, there is no exact temperature right for fish. They do however have an ideal range. Their natural environments will have changing temperatures based on sun, rain and different times of the year. Temperatures can vary by as much as 30°F or possibly more without harming the fish.

You may think these temperature swings are enough to cope with an aquarium heater that is too hot, yet, unless the temperatures are extremely hot, it is more to do with the speed of these temperature changes.

An aquarium will heat up or cool down much faster than a larger body of water. In the wild, it takes a long time for this water to change temperature. Because an aquarium will heat up faster, it is because of this why they have heaters in the first place.

What Should I Do With High Water Temperatures?

Once you have water that is rising in temperature, different issues will arise. Temperatures that rise above 90°F will cause the most significant problems. Fish will become more active, and as a result, they require more oxygen.

You may think this isn’t too much of an issue, yet warm water holds less dissolved oxygen than cold water. If your tank is balanced and there is a reasonable amount of oxygen for your fish population to breathe, this could quickly change, and your fish don’t have enough oxygen to breathe correctly.

Another issue is that you will suffer from Ammonia spikes. Oxygen is needed for the beneficial bacteria to do their job, and once they can’t do this, ammonia levels rise, and your fish suffer.

Now, if you see this happening, you need to do something quickly, although not too fast to shock your fish.

The very first thing you need to do is turn down the temperature on your aquarium heater. While many experts say unplug your heater, you may drop the temperature too much, and also quickly. It is safer to do the following while keeping an eye on the temperatures with your aquarium thermometer.

While one or two of these methods may be sufficient, you may find yourself doing everything to lower the temperature of your aquarium to a safe level where you can control it, and then resolve the issue of why it rose in the first place.

1. Add More Oxygen

Making sure there is adequate oxygen can be the first step you take. There are so many disturbing things, which can happen; this is vital to save your fish and all the bacteria.

2. Cool the Room

One thing you may not notice is the ambient temperature. If you begin trying to cool your aquarium, and the room where you have your tank is warm, then it will be harder to do.

3. Remove the Hood

If your tank has a hood, especially one with built-in lights, you will need to remove this to help the water temperature fall. You do need to be careful of any fish that may want to jump from your tank. If your lights are not part of the hood, then turn them off until you resolve the warm water problem.

4. Use Your Filter to Cool

This method will only work if you have an external filter. You can run the tubes through cold water or ice packs. As long as you don’t have a sudden drop in temperature, it could be enough to cool the tank temperature without causing any harm to your fish, or damaging the cycle of your tank.

Water Changes to Cool Your Aquarium

One way to reduce the heat is by carefully making small water changes. These should not be over 25% of your tank volume in anyone go. The water you are exchanging should not be too cold because this will affect your fish. It should ideally be a couple of degrees colder than the water in your tank.

While it is never a recommendation to drop ice directly into your tank, for one, they will most likely not be of the same water type, such as reverse osmosis or dechlorinated water. Second, they will make the temperature plummet, and it will shock your fish.

If you do use ice of any form, you can place ice in a Ziploc bag and dip this into the water, or you can do the same with ice-cold water. By dipping it in, you can keep an eye on the temperature as it begins to fall.

One thing to be sure of is the temperature doesn’t fall more than 2 to 3 degrees in any four hours.

Using Fans and Chillers to Cool Your Aquarium

Although this method may take a little longer to cool the water temperatures of your tanks water, it can be less shocking to your fish.

If you can place either one large fan or a couple of small ones to blow across the surface of your tanks water, it helps with evaporation and thus aiding in cooling. It is possible to purchase clip-on styled cooling fans that make them easy to sit in position.

The extreme way to cool your aquarium is a chiller unit. However, if it is an emergency, then these won’t suffice, as you won’t have one ready. These are intended for long-term use where waters are prone to rising to unsafe levels. An aquarium chiller unit will also need to be purchased according to tank size, and these take a considerable investment.

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The Right Heater for Your Tank

Heater issues can stem from the wrong heater size in a tank. If they are too small, then they will only heat the area around the heater and leave the remainder of the tank cool. One that is too big will overheat the water and thus cause the above issues.

Knowing the size of the heater you need is half the battle in maintaining the ideal water temperatures. As a rule, you require between 2.5 and 5 watts of heat per gallon of water. However, knowing that a larger tank will lose heat slower than a smaller tank can have a bearing on this guide.

Tiny aquariums are challenging to heat, and you may need to resort to a miniature submersible heater. On the other hand, if you have a tank of around 70 gallons, you will be looking at a high power aquarium heater of approximately 200-300 watts in power.

Ambient room temperatures also have a bearing on this; if you have a warm room, and without a heater, the water temperatures are around the mid seventy degrees Fahrenheit, then you can use a smaller heater.

No matter what size you have, you should have one that will reliably cut off when you set the temperature. This is one way you can be more confident your water temperatures won’t go too high.