Why Is My Hot Tub Dropping Temperature

Why Is My Hot Tub Dropping Temperature (7 Reasons & Fixing Guide)

Is dropping temperature from your hot tub water continually? Looking to find reasons with easy solutions? Don’t worry; I am going to share the top reasons why your hot tub dropping in temperature. I’ll also share some handy tips on how to troubleshoot and fix the issue.

So, keep reading to learn.

A hot tub should have an average temperature between 37°C and 39°C, with the maximum being 40°C. However, after hours of research and according to hot tub experts, the top sources of temperature loss are dirty filters, low water levels, and faulty hot tub parts. Plus, external factors include the surrounding cool temperatures and heat loss from jets and blowers.

7 Top Reasons: Why Your Hot Tub Dropping Temperature with Solutions

1. Filter becomes clogged and dirty

Your hot tub filters would be clogged and dirty due to various reasons. When these are clogged, they can lead to some chilly consequences! Hot tub filters may clog, mostly due to the body oils, lotions, and other yucky stuff that comes from our skin when we soak. This can slow down the heating process, which means the temperature might drop when you least expect it.

Another sneaky cause of clogged filters is tiny debris like leaves, grass, and dirt. These little particles can block the water’s flow too. Sometimes you might find hair tangled in the filter, causing even more clogs.

But don’t worry; I have a solution for this! One easy fix is to clean your filter regularly. You can rinse your hot tub with a hose or soak it in a special cleaning solution. This will help wash away the entire gunk and keep your hot tub’s water flowing smoothly even clean and cristal.

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You can also use a skimmer net or vacuum to remove debris before it reaches the filter. If you control all these things, you might stop dropping the temperature in your hot tub.

2. Low water level, closed valves, blocked drain covers

Why can low water levels, closed valves, and blocked drain covers cause the temperature to drop in a hot tub? And how to fix these issues!

According to most pool experts and my knowledge, it would be due to the water level being too low. If your hot tub does not have enough water, the heater struggles to warm it up and maintain the desired temperature. You can fix this by simply filling your hot tub with more water and ensuring it reaches the recommended level.

Another reason, I think, is closed valves. We all know that valves control the flow of water. So if your tub’s water pump valves are closed, the water will not be able to circulate properly. That’s why, water will not mix with the cooler water. You can read our guide to softening hot tub water naturally.

You can simply solve this by finding the water valves in your tub and then cleaning them to ensure a smooth flow of water.

Sometimes debris like leaves, twigs, or other gunk can clog up your drain covers. As a result of which it affects the water circulation and makes it hard for the heater to warm the water evenly. To combat this, you should regularly clean your drain covers, try to remove any visible debris, and give them a good scrub.

3. Problem with the hot tub thermometer

Dropping hot tub temperatures could be due to the hot tub thermometer! The little gadget that tells you the temperature of your water plays a big role in keeping things toasty. Sometimes, the thermometer does not provide accurate data. This can lead to the temperature dropping in your hot tub.

Hot tub thermometer

If you do not understand why this happens, you should know what the thermometer measures. With the right measures, you can maintain the right warmth in your tub water. However, if your thermometer does not work properly, it may give you false readings, causing the heater to turn off too soon. This can make your hot tub water cooler than you want.

To solve this issue, check whether your thermometer is calibrated or not. You can also use another thermometer and compare its readings with those that you know are accurate. If you find a difference, adjust your hot tub thermometer accordingly.

Moreover, place your thermometer in a good location, away from direct sunlight or air jets, as these factors can affect its readings. Also, make sure the thermometer is clean and free of debris, as this can also cause inaccurate temperature readings.

4. Cool temperatures around the hot tub

Did you know that the cool air surrounding could be the sneaky culprit making the water temperature drop? When you enjoy a relaxing soak in your warm and cozy hot tub, you might not realize the chilly air can sneak in and steal your heat! But don’t worry; I have a solution for this.

A well-insulated hot tub cover is like a cozy blanket that traps the heat inside. As a result of which your tub’s water stays warm and inviting. Don’t forget to tighten the cover when you’re not using your tub.

Thermal blanket for water
Thermal blanket

You can use a thermal blanket, which is a handy little invention. A thermal blanket floats on the surface of the water and acts as a barrier between the air and your precious heat. Plus, it is super easy to put on and take off whenever you want to use your hot tub.

You can install a windbreak around your hot tub, which is another good idea to solve this issue. A windbreak will help block the cold breeze from sneaking in and cooling down your water. Not only does it prevent a drop in temperature, but it also gives you some extra privacy.

Sometimes hot tub temperatures drop due to the tub’s heater. So you can invest in a more energy-efficient hot tub heater. Some heaters work better in cooler weather. So I advise you to check the labels and choose a heater that’s designed to perform well in your area’s climate.

6. Low water level

Your hot tub water temperature could be drop due to low water levels. If the water level drops below the recommended level (1/2 to 2/3 of the skimmer hole), it can cause the heater to shut off automatically. Although automatic shut-off is a safety feature that is only built-in to prevent damage to the hot tub’s heating elements.

You can easily check water level condition of your hot tub; just simply look at the water line on the side of the tub. If you see water levels below the line, you will need to add more water.

So I highly recommend monitoring the water level regularly. If you find any change, try to add water as needed to prevent temperature loss and any potential damage to the tub’s heating system.

7. Cool temperature around the hot tub

If your hot tub is located outside, the cool temperature would reduce the heat retention of your tub. Also, wind and rain can contribute to decreasing the temperature.

In order to combat this, you can consider adding insulation or building a structure around your hot tub to help keep the warmer air inside. Additionally, you can use a hot tub cover to retain heat and prevent temperature loss.

8. Heat loss from spa jets and blowers

You may face a temperature drop in your tub’s water due to spa jets and blowers. It can happen when jets and blowers aren’t sealed properly. In this case, air flows through jets or blowers and releases heat from the water.

To solve this heat loss issue, try to ensure your spa’s features are properly maintained and sealed. Also, you can check the jets and blowers to see if any seals or gaskets are worn down or damaged.

4 Faulty Parts That Cause Temperature Loss

If you notice a sudden temperature drop in your hot tub water, it can be caused by a variety of issues, including those discussed above. For one of these reasons, I think faulty parts are the main culprit.

Here are some of the parts that could be causing your temperature loss:

  • Heating Element: It is one of the most common parts of a hot tub that commonly fails to heat or is damaged. Somehow, if the heating element stops working, your hot tub will not be able to maintain its temperature.
  • Thermostat: If your tub’s thermostat does not work properly or is damaged, it won’t be able to accurately regulate the temperature.
  • Electrical Connections: If you have loose or damaged electrical connections, it might be causing your hot tub to malfunction and lose heat.
  • Circulation Pump: Without a working circulation pump, your hot tub will not move water through the heating system, which can lead to temperature loss.
Water circulation pump
Water circulation pump

If you find fault with any of these parts, you should check them and have them repaired by a professional.

Frequently Asked Questions

What can I do to prevent my spa from cooling down too quickly?

To prevent your spa from cooling down too quickly, you can set a higher temperature in your spa, consider adjusting the set temperature based on the current weather conditions, or avoid using the blower, which can take a lot of heat out of your spa.

Can poor insulation cause the temperature of a hot tub to drop overnight?

Yes, poor insulation is one of the primary culprits behind a hot tub’s temperature drop overnight.

Why is heat loss through the surface a problem?

Your hot tub may lose heat through its surface if it is not appropriately covered. The heat loss is accelerated when the ambient air temperature drops at night. Hot tub covers are designed to retain heat and prevent evaporation. When the cover is not used or is damaged or ill-fitting, the tub’s heat loss increases. According to the U.S. Department of Energy, using an appropriate cover on your hot tub can reduce heat loss by up to 95%.

The Bottom Line

Those are some of the common reasons why your hot tub might be dropping in temperature. Remember, try to act quickly and troubleshoot the issue to prevent further damage to your hot tub.

If you are unsure about anything, it is always best to contact a professional. If you have any hot tub maintenance tips or hacks, please share them with us in the comments below!

Hey, after fixing the temperature-reducing problem, you can learn our in-depth answer about how long it may take to heat your soaking tub.


Hi, I'm Shimul, the founder of Pooltub Life. I'm excited about sharing the latest outdoor living trends with you. My goal is to provide you with up-to-date information that will help make your POOL & HOT TUB stylish and enjoyable. Read About Me More । Follow on Facebook

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