Why Is My Hot Tub Water Green

Why Is My Hot Tub Water Green? Reasons and Preventions

If you have had a hot tub for a long time, you must face the problem of having green water in your tub, right? Undoubtedly, greenish water is the most common hot tub problem; most owners face it. That must be the reason many of them why their hot tub water is green.

Usually, there are many different reasons behind this irritating problem. The most common reason is the algae and the water material that is not suitable.

However, preventing this problem is easy; if you are already in it, you must find a reason to fix it. Do you know how to find it? No need to be worried. My topic of discussion today is precisely what you are thinking about. Let me dig into the facts for you.

Reasons Behind Your Hot Tub Water Is Green

There can be different reasons that can make your hot tub water greenish. To fix the problem, the first thing you need to do is to salt out the issue.

Once you know the real culprit here, you will learn how to fix it automatically. Let’s understand the common reasons that can make your hot tub water greenish.

Algae Growth

Algae in hot tubs are very rare as hot tubs generally remain covered. If daytime it is covered and provided with sanitizers, algae growth is highly unlikely. Sometimes algae can grow and be of any color, such as green, yellow, black, etc.

green algae in hot tub water

If the hot tub base or floor is slippery and the water seems a bit greenish, it could be algae growth. One of the reasons for this condition is merging algae-inflicted swimsuits in the bathtub water. So, washing clothes after bathing in ponds, lakes, and rivers is always suggested.

Excessive Metal Content

Another common cause of the hot tub water turning green is the excessive presence of metal elements. Water from wells and taps can have traces of copper and iron, as they are common in such sources. Even the long iron-based pipe ways make that water hold metal content.

In the oxidation process in the tub, the copper turns greenish. As a result, the water seems green. If the water’s TA and pH level is checked, the tubs or spas water will seem clear with a green tint. Not just the metal traces, it depends on the water temperature too.

Unbalanced Sanitiser Levels

Sometimes it can grow due to the quality of sanitizers used in the water. The water turns green if you use a very low-quality product in small portions. The sanitizer levels should always be balanced in the tub’s water.

It does not matter which sanitizer you use on the bath or spa water. Most people use chlorine and bromine as water sanitizers. You should use it regularly in the proper balance.

Excessive Mineral in the Water

A high amount of minerals in the water can turn the tub water green or of different sorts. This is a very common scenario. The local water source, wells, and even water supply lines can saturate minerals in the water.

If copper is dominant in the water after the regular shock process in the bath water, the water can turn greenish. In this condition, you can use mineral removal products to clean up copper and similar minerals.

Leisure Time Chlorinating Granules for Hot Tubs

Leisure Time Chlorinating Granules for Hot Tubs

This chlorine-based sanitizing system is easy to use and easy to maintain. With its active ingredient, Sodium Dichloro-s-Triazinetrione Dihydrate, you can rest assured that your hot tub will be clean and safe.

Chlorine Shock

One of the main reasons for your hot tubs or spa’s water turning green or discolored is chlorine shock. Yes, sometimes too many chemicals or sanitizers can hamper the condition. Even algae growth increases manifold in that condition because of the shocking treatment.

The process gets even quicker if the water stays for an extended time without any circulation or movement. According to the CDC’s report on hot tub facts, it is essential to maintain water free of chlorine or containing only 3–10 parts per million or ppm or bromine in a hot tub.

Filtration System Issues

If the filtration system in your hot tub is not functioning correctly, it may be unable to remove all the contaminants and bacteria from the water. This can lead to an overgrowth of algae, which can turn the water green.

A dirty or clogged filter can reduce the effectiveness of your filtration system, allowing algae and other contaminants to build up in the water.

Unbalanced pH Level

An unbalanced pH level in your hot tub water can cause many problems. And one of them is making the water greenish.

Usually, the pH scale measures how acidic or alkaline a solution is, and in the case of hot tub water, a pH level between 7.2 and 7.8 is considered balanced.

If the pH level is too high (above 7.8), it can cause scaling and cloudiness in the water and reduce the effectiveness of your sanitizer. A report by the CDC recommends maintaining the pH level of the water at 7.2–7.8 for a hot tub.

Steps to Prevent Your Hot Tub Water from Turning Green

As you know everything about the reasons behind your hot tub water turning green, you can take the necessary steps to solve it.

You can follow the below steps to keep your hot tub fresh and well-maintained.

Step 1: Test the Water

The first step in resolving green hot tub water is to test the water using the test strips or kit. This will provide you with information about pH, sanitizer, and alkalinity levels. You can check CDC’s recommended way to test your hot tub water.

test the water of hot tub

Step 2: Shock the Water

If sanitizer is low, you must shock the water with a hot tub shock treatment. This will kill off any bacteria or algae that may be present in the warm water.

Follow the manufacturer’s instructions carefully when using a shock treatment.

If you have issues with foam along with green water in the hot tub, follow another guide to resolve the problem.

Step 3: Clean the Filter

A dirty or clogged hot tub filter can reduce the effectiveness of your filtration system. It can allow algae and other contaminants to build up in the water.

Deep clean or replace the filter as needed to ensure proper filtration. So, cleaning the filter before refilling it with fresh water is essential.

Step 4: Adjust the pH Level

If the pH level of the water is too high or too low, you will need to adjust it using pH increases or decreases as necessary. This will help balance the water chemistry and prevent further algae growth.

Step 5: Add Algaecide

An algaecide may also be necessary to help kill off any remaining algae in the water. Make sure to choose an appropriate algaecide for use in hot tubs and follow the manufacturer’s instructions carefully.

Step 6: Drain and Refill the Water

If the water is still green after taking the above steps, you may need to drain and refill the hot tub. Draining your hot tub can help remove any remaining contaminants and start fresh with balanced water chemistry.

Step 7: Regular Maintenance

To prevent future occurrences of green hot tub water, it’s essential to regularly maintain your hot tub by testing it regularly, cleaning the filter, and adding hot tub chemicals.

This is the easiest yet most effective way to keep your hot tub water well-maintained and safe. Make sure to check the water condition and test the water once or twice a year.

Final Call

Having a hot tub with green or discolored warm water is a real pain. Once it starts, you must suffer a lot to eliminate it if you don’t know the exact reason.

That’s why I suggest finding the reason first and then taking the necessary steps to fix it. But taking the required initiatives to prevent your hot tub from getting greenish water is even wiser.


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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