Hot Tub Water is Green (Here’s How To Fix It…)

By Dillon •  Updated: 05/25/21 •  17 min read

Why is my hot tub water green?

Green hot tub water happens when there is excessive growth of algae or bacteria in the hot tub, which can be caused by dirty filters and chemicals that are not often replaced. Other problems include pH levels, sanitizer levels, and filter type. To fix green hot tub water, add a large amount of chlorine or bromine sanitizer. Total sanitizer should be between 3 and 5 parts per million (PPM). Shocking the hot tub with a chlorine oxidizer will also help. Finally, draining and cleaning the spa is the best solution.

Check out my list of high-quality hot tub products to help keep your hot tub clean and running great all year long!

My recommended product to help you test your spa water for accurate pH, alkalinity, bromine, and chlorine readings is the AquaCheck Trutest Digital Reader.

A year or so ago, I experienced green hot tub water and wondered how it could be fixed.

What’s wrong with my hot tub water? It is green, smells terrible, and I can’t see anything in it! These are all signs of a dirty hot tub. Hot tub water that is cloudy or has algae growth should be treated right away to prevent the spread of bacteria and other harmful organisms.

In your hot tub, water can get cloudy for several reasons. If you have been using the same filter and chemicals regularly without replacing them or topping up with new ones, these things are likely to cause the problem.

This article will discuss what causes hot tub water to turn green and how you can keep the water clear.

I will also talk about how Sanitizers, pH levels, filter types, and dirty filters all affect your hot tub’s clarity.

Let’s get started!

Why Is My Hot Tub Water Green?

Some causes for green hot tub water include dirty filters, which can trap organic particles and other debris. Dirty hot tub pumps are another thing that may cause water to turn green. A build-up of algae in the plumbing system is also another reason for hot tub water turning green.

If you have been using the same filter and chemicals regularly without replacing them or topping up with new ones, these things are likely to cause the problem.

The pH levels in your hot tub could affect how clear it appears by either making it more acidic or alkaline (depending on its natural state). If there’s an imbalance between these two conditions, the chlorine will not work correctly, and bacteria from dirtier areas like feet might find their way into your hot tub through cracks.

When it comes to pH levels, you want to keep the hot tub at a pH of between seven and eight. If it gets too acidic, the chlorine will be less effective in killing bacteria and algae.

Sanitizer levels should be at the recommended two parts per million (PPM). If it’s not, that means there is a build-up of bacteria and algae.
Your sanitizer type must be compatible with filter types as well. For example, some filters are not suitable for saltwater or bromine because they can’t get rid of the chemical residue from these treatments like other filtration systems do!

Lastly, change dirty filters often or replace them entirely if possible, so green hot tub water doesn’t happen again!

If you’re interested in knowing if you can leave a hot tub empty, check out our article on the subject for more information.

Hot Tub Water is Green and Smells

Hot tub water that is green and smells is a result of several different issues:

  1. It could be that you have a stain on the hot tub floor or some other type of dirt contaminant in your water, and this has created an unpleasant smell.
  2. While not as expected, there are instances where strong chemicals from a sanitizing agent can react with metal heaters to produce hydrogen sulfide gas which is what most people associate with rotten eggs!
  3. This process will also result in green hot pouch water coloration due to the copper corrosion caused by these chemical reactions.

Lastly, suppose something is wrong with your filter system. In that case, either bacteria colonies or algae growth can block filters, so they cannot work effectively against particles found inside the spa.

green hot tub water

What is Hot Tub Algae?

Hot Tub Algae is a type of bacteria that thrives in hot water. Hot tub algae can form on the surface, grow inside vinyl liner or live at the bottom as filter clogs. Its whitish-green coloration makes this bacteria very noticeable, and it creates an unattractive appearance for any hot tub owner.

Algae in a hot tub is a natural occurrence caused by hot water, warm temperatures, and nutrients. Hot tub algae can be found on the surface of your hot tub or stuck to surfaces like tiles.

If you’re looking to remove mold from an inflatable hot tub, read our article on the subject for more information.

How to Prevent Hot Tub Algae?

One of the best ways to prevent hot tub algae is by conducting a sanitizer shock treatment every month. By shocking your spa with a high level of chlorine or bromine, you will be able to kill off any harmful organisms that might have been growing and causing problems for your water chemistry over time. It’s also important not to disturb surfaces inside the spa, such as walls, seats, ladders, etc., since they can easily collect bacteria particles, ending up in the water when someone gets into it.

Some other steps to consider:

These few simple tactics will help keep algae from forming in the future. But first, you need to address the algae already in the hot tub.

Check out this great article from Home Depot about getting rid of algae in a pool.

How Do I Get Rid of Green Water in My Hot Tub?

If your hot tub is green and smells, you’ll want to start by checking the pH balance of the water. Most people don’t know that when there’s a high amount of chlorine or bromine in the hot tub water, it can cause it to become cloudy, which will then make it seem like something must be wrong with the filter system. However, the real issue could come from dirty filters and sanitizers not being balanced correctly due to lack of cleaning or maintenance.

The best way to clean and rid your spa of green water is to drain it and then wash it thoroughly.

Check out our article on how to clean a hot tub for our best tips.

Drain and Clean the Hot Tub

You’ll want to drain the hot tub water and clean all of its surfaces. You should use a hot-tub cleaner that includes chlorine to rid any algae from the sides or bottom. After you’ve done that, take out your filter system and scrub along with it as well so that everything is thoroughly cleaned before reassembling it back into place.

Add line flush product to the water before draining. This would dissolve all the biofilm accumulated in the pipes. Allow the water to circulate for 30 minutes after adding line flush product. You will see foaming on the surface of the water, but this is normal.

There are two methods on how to drain a hot tub. The first is to use a submersible pump to suck the water out of the spa. A 1/4 horsepower utility pump should do the trick. The second is to attach a hose to the drainage valve and let gravity do the work. It can take up to 2 hours to drain a hot tub. However, this depends on the size of the spa and the amount of water it holds.


Refill The Hot Tub With Fresh Water

If you’ve cleaned your hot tub thoroughly, then this step is even easier. But, first, you’ll want to refill it with fresh water and change the chlorine level to eliminate any remaining algae from the cleaning process.

The best way to refill a hot tub is to use a hose or tap water. If your hot tub is a hard-sided spa, then place the hose inside one of the filter housings to fill the spa plumbing to remove any air out of the system. Filling a hot tub could take 1 to 2 hours, depending on the size of the spa. Don’t fill the hot tub if it’s below freezing outside, and remember to keep the hot tub shut off at all times until it’s filled with water.

Why Does Hot Tub Water Get Cloudy?

Cloudy water is often a result of chemical imbalance within your hot tub. This imbalance leads to insufficient sanitizer levels causing bacteria and other organic material to spawn in the water, making it cloudy. To prevent this, add 30g (1 capful) of oxidizer to the spa. Next, add another 30g of sanitizer (either chlorine or bromine) to clear the water. Sanitizer levels should be between 1-3 PPM for chlorine or 2-6 PPM for bromine.

Hot tub water gets cloudy for a variety of reasons. Some common causes are high chlorine, chloramine, or bromine sanitizer in the hot tub, dirty filters or filter cartridges, and pH issues with too much acidity (low pH) or alkalinity (high pH).

The best way to determine what is causing your hot-tub troubles is to test the water at least once every week.

Check out this great article from Swim University about how to fix cloudy spa water.

What are some of the things that cause cloudy, hot tub water?

Low Water Sanitizer Levels

Did you notice the cloudiness of water after heavy use? Then low water sanitizer levels could be what’s causing the hot tub water to be cloudy. That’s why I use hot tub sanitizers; to remove bacteria and other organic contaminants. If the rate of things being added to the water is greater than the speed of the contaminant being removed, cloudiness can appear.

Check out our full article on chlorine tablets and how to administer them.

Sometimes it’s possible to add too much sanitizer to a spa. If this has happened to you, read our full article on the subject for some tips.

Below is our recommendation for chlorine tablets.

Our recommendation for a chlorine dispenser.

High Calcium Hardness and pH Imbalance

If you are from an area with hard water, high calcium amounts can make your hot tub water cloudy. Check the total alkalinity level (TA), pH, and calcium hardness and put them under recommended ranges.

Calcium makes the water more alkaline, and that causes cloudiness. So, make sure the calcium hardness levels are not greater than 300ppm. A chemical balancer is an effective method of adjusting the calcium hardness, pH, and alkalinity of water.

Similarly, if the total alkalinity levels are more than 150ppm, metal carbonates can build up, making the water cloudy. Even if the cloudiness is not a problem, you should keep the total alkalinity under the limit. If they rise too much, it can become difficult to control them. You can use a pH reducer to keep the levels under 100ppm.

To raise total alkalinity I recommend Spa Essentials Total Alkalinity Increaser.

Our recommended product to raise pH in hot tubs is Spa Essentials pH increaser Granules.

Our recommended product to decrease pH in hot tubs is SpaGuard pH Decreaser.

Total Dissolved Particles

A hot tub that has held water for more than four months develops high TDS levels (total dissolved particles). This is because water only absorbs a certain amount of chemicals. After that, the particles move around in the water as solids. These undissolved particles can cause the cloudiness of water. Now is the time to drain and refill the hot tub. You don’t have to wait for the water to become cloudy, as you can check the TDS levels. If the TDS level is above 1500ppm, then replace the water.

Dirty Hot Tub Filters

The most common reason why spa owners face cloudy, hot water is dirty hot tub filters. If you forgot to clean the filters, now is the time.

The job a hot tub filter does is catch the “gunky stuff” floating in the water. Over time, various types of small matter can get stuck in the filter and reduce the filter’s efficiency to do its work. The filter becomes overloaded with grease and other contaminants, and its effectiveness decrease over time.

Another possibility could be a bad quality filter. Dirty water might be escaping the filter and causing cloudiness. Make sure that you have positioned the filter correctly. If the problem remains, try replacing the filter.

Is Green Hot Tub Water Safe?

Green hot tub water is not safe because it makes you more susceptible to getting sick. Green hot tub water can cause respiratory problems, skin irritation, and eye infection. As a result, people with compromised immune systems are at risk in particular. 

It’s always best practice to keep your hot tub clean by emptying or draining green spa water regularly to avoid running into these issues.

How Do I Keep My Hot Tub Crystal Clear?

Keeping your hot tub crystal clear is possible with some simple and inexpensive steps. First, hot tubs need to be emptied or drained regularly for the water not to turn green. You can also use a filter that filters out all impurities, including dirt particles and contaminants.

Try adding chemicals like chlorine or bromine tablets which will reduce bacteria growth even further. Another option would be using an automatic feeder so you don’t have to remember how often you should add chemical treatments yourself!

However, even without any of these methods, it’s best practice to always clean up cloudy floating debris by hand first before deciding what treatment might work best. If you have problems with hot tub water turning green, murky, or smelly, it’s best to consult an expert for help!

Though the problem may be caused by dirt particles and contaminants that get into your hot tub through leaves and dead insects found on top of the surface of the water – which is why keeping your lid closed as much as possible will prevent this issue from happening in most cases.

bromine tablets for hot tubs

Can Too Much Bromine Turn Water Green?

The chemical bromine can cause hot tub water to turn green if it is not properly balanced with other chemicals. When used in conjunction with chlorine or biguanide sanitizers, bromine will produce a substance called chloro-bromamines which are highly irritating and will discolor the water into a light shade of green.

This reaction occurs because there is too much bromine present in relation to these other chemicals. You might be using more than what you need for proper disinfection for your hot tub’s size (in gallons). Make sure that you’re adding enough chlorine and biguanide before adjusting anything else!

Spa Turns Green After Adding Chlorine

There are a few reasons why your hot tub could turn green after adding chlorine. Chlorine is the number one chemical that causes hot water to turn green. This is due to too many chloramines, high pH levels (which makes it harder for sanitizers to work correctly), too little alkalinity, or bad circulation in the spa’s plumbing system.

If you have recently added chlorine but not yet swished around all of the chemicals with enough force, then this should correct itself over time as everything mixes well.

The proper chemical balance in a hot tub is essential to keep hot tub water clear.

The pH of a hot tub should be between seven and eight (optimal for sanitizers to work correctly). If the pH is too high, then upsetting chemicals may cause green-tinged water, but you’re at risk for bacteria growth if it’s below six.

If your spa has been flooded with bromine or chloramines, this can lead to discoloration in hot water as well. To fix this problem, try using something like Spa Shock.

If your spa smells like chemicals, it may be because of oxidizer issues. Check out our full article on chemical smells for more information.

How Often Should I Shock My Hot Tub?

Hot tub shock is the process of adding a large dose of oxidizer chemical to the hot tub water. This process is also known as oxidizing. An oxidizer is usually capable of breaking up organic compounds. Adding enough chlorine to this mix will kill any bacteria resulting in clean spa water. It’s important to shock your hot tub regularly for the best results.

Many factors determine how often you should shock your hot tub. The most crucial factor is the amount of bromine or chloramines in the water. If there’s a lot, then it might be necessary to use something like Spa Shock every couple of days. But if they’re still at safe levels, then once every two weeks may be sufficient enough for cleaning and maintenance purposes.

Hot tub shock removes organic contaminants.

You generate many organic contaminants into your hot tub every time you use the spa. The organic pollutants arise from lotion, shampoo, sunscreen, makeup, dead skin cells, hair, and any other remnants that your body acquires from the surroundings. The number of organic contaminants is more significant when many people soak in one hot tub.

You can reduce this problem by rinsing or showering before you soak into the hot tub. But not all the organic compounds are eliminated. That is why you must use the hot tub shock to break down the organic contaminants. This will help you avoid scum or cloudiness in the water after some time.

Check out our full article on how to clean inflatable hot tubs for some quick tips!

Below is our recommendation for non-chlorine.

Our recommendation for chlorine shock.

Consider Using a Water Care Monitor

Monitoring the health of your hot tub can often be challenging if you are not testing the water on a regular basis. This can also be a problem if you go on holiday or you are unable to take care of your hot tub due to mobility issues.

The pHin Smart Water Care Monitor for pools, hot tubs, and inflatable spas continuously tests the water and alerts you when to add chemicals with the integrated mobile app.

This water care monitor also takes constant readings of the temperature inside your hot tub. This will give you peace of mind while away from your spa.

The mobile app will inform you when to add chemicals such as chlorine, and how much chemical is recommended. This is done by entering your hot tub or pool’s unique dimensions.

Simply scan the bar code of any chemical brand and the pHin app will calculate how much chemical is to be added to the water. Most products and brands are recognized by the application.

The pHin device will sample water more than 1000 times per week to give you an accurate reading compared to using test strips.

The pHin device works with different water types including chlorine, bromine, and saltwater hot tubs, swim spas, inflatable hot tubs, and pools.

This unique device comes with a lifetime warranty to ensure your water remains clear and ready for you to use at all times.

Hot Tub Water is Green: Conclusion

hot tub water is green

In conclusion, green hot tub water results from the hot tub water getting cloudy and algae growth. It is caused by pH, sanitizer, organic contaminants in the air or on your skin before entering the hot tub. You can prevent it by rinsing with clean water or showering to remove most of these factors.

I hope our article has helped you to understand the causes of green hot tub water.

If you’re interested in knowing more about the best water temperature for hot tubs, check out our article on spa temperatures.

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Dillon

I'm Dillon, creator of SpaToolKit.com. During the day I'm a software developer for an engineering company. At night I enjoy sitting in my hot tub and relaxing. My hope is that Spa Tool Kit will be a place where you can find the best information on hot tubs, spa equipment, setups, parts, and accessories. Let's get started!