How to Remove Hot Tub Scum? (Green, Brown, Blue-Green)

There are a few things that can turn your idea of a warm relaxing evening in your hot tub into a disappointing one. One of these is hot tub scum.

Hot tub scum simply put refers to the oily grime that floats on the surface of the water in your hot tub. It makes the water unclean and unsafe. Many people know this. But, what most people don’t know is how hot tub scum accumulates in their hot tubs and how they can prevent and get rid of it.

Don’t worry though because you are about to learn everything you need to know about hot tub scum, its prevention, and how to remove it from your hot tub.

What Is Hot Tub Scum?

Hot tub scum is the oily grime that you notice on the surface of the water in the hot tub. This oily grime could be green, brown, or have another color.

If you notice a change in the color of water in your hot tub or you notice that the is starting to smell or have an oily feel, then you have hot tub scum.

The scum forms and accumulates as a result of different causes. So what causes hot tub scum? Let’s find out.

What Causes Hot Tub Scum?

To most people, hot tub scum is caused by dirt and dust particles that fly around especially if the hot tub is located outside. While this is true, it isn’t the only cause of hot tub scum. The oily grime is caused by different factors including the following.

Personal Care Products

This becomes a problem if you take a bath in the tub without removing these personal care products from your body first.

The deodorants, shampoo, perfume oils, body oils, hair-care products, and the lot that we use on our body contain oils and other substances.

Many shampoo products for instance contain tea tree oil which helps to keep the hair smooth. When you take your bath in the hot tub without removing or washing these products off first, you are directly contributing to the level of scum.

Food and Drinks Residue

What’s better than having a warm soak in a hot tub? Having a snack alongside. Eating and drinking in your hot tub have become the norm. A lot of people do it but this doesn’t make it right. Eating and drinking in the hot tub are wrong both health-wise and hot tub-wise.

In addition to the health risk, eating in the hot tub also adds to the scum in your hot tub. When you eat, food residue gets into the water and this causes hot tub scum later. This is even more serious if you eat oily foods like fries, meat, and the likes.

Bodily Residue

It’s gross but it’s a cause of hot tub scum. The bodily residue is one of the main causes of scum. Many of us use our hot tubs in the evening and usually after a stressful day. The bodily fluids that emit from your body add to the scum.

Being in the hot tub also means your body is exposed to the heat of about 100 degrees Fahrenheit. Your body system releases sweat to cool down the skin. The sweat that is produced is a mixture of different compounds and also a way of passing out waste from your body. This sweat goes directly into the water.

Asides from the sweat, there is also a possibility of tiny droplets of feces being introduced into the water (eww!). The combination of all these bodily residues and fluids contributes to the scum in your hot tub.

Hot Tub Oils

Many people add hot tub oils to the water in the hot tub because hot tub oils give pleasant fragrances. As the water and oil are being heated, the oils produce a mixture of pleasant scents that get you even more relaxed.

The problem is these oils also contribute to scum. By adding hot tub oils to the water in your hot tub, you are directly adding to the scum in the water. This doesn’t mean you shouldn’t use hot tub oils. After all, they improve the relaxing feeling you get in the hot tub but you can limit the number of oils that you are to the water.

Dirt and Debris

If your hot tub was installed outdoors, then you already know about the battle of keeping leaves, dirt, and other debris out of your hot tub water.

These dirt particles also contribute to the scum in your water. If your hot tub is left open and unattended, this debris and dirt will get into the water and accumulate to form hot tub scum.


I bet like most people, you don’t know that putting on jewelry in the hot tub is wrong. This is because the water in the tub is usually treated with chemicals like chlorine to prevent the formation of algae and bacteria.

The chemicals you use in treating the hot tub water don’t go well with your jewelry. Silver for instance creates a tarnish when it reacts with chlorine.

Gold and other accessories too can also be damaged by chlorine and other chemicals used in the hot tub. The reaction of your jewelry and these chemicals will lead to the accumulation of hot tub scum.

Damaged Hot Tub Filters

Your hot tub filters work like a sieve. The filter sieves out dirt, debris, and other waste from the water. If the filters are damaged or worn out, then you can expect to have a lot of hot tub scum and grime in your water because nothing is filtering out the dirt.

Other causes of scum include poor water chemistry, rodent infestation, poor maintenance of the hot tub, and so on.

Hot Tub Scum Types

Yes, there are different types of hot tub scum. This is because there are different causes of hot tub scum. So what are the types of hot tub scum? Keep reading to find out.

Brown Hot Tub Scum

Brown scum is caused by a high pH level in the water. As stated earlier, the water in the hot tub is usually treated to keep germs out. If you use too many chemicals or over-shock the water in the hot tub, you will most likely notice brown scum.

Using too many chemicals will cause a high pH level in the water and the minerals in the water like iron will start to react with the chemicals used. This will cause brown scum and can also cause discoloration on the inner walls of the hot tub.

Green Hot Tub Scum

Green hot tub scum is caused by a high metal level in the water. This will cause you to notice green oily grime on the surface of the water. If you have a high copper level or magnesium level in the water, you will most likely notice the green scum.

The dissolved metal reacts with the chemicals like bromine used to clean the water. This reaction causes a green residue to form on the surface of the water.

Blue-green Hot Tub Scum

The blue-green hot tub scum is the hybrid of hot tub scums. This scum is a combination of different causes such as bodily residue, body care products, food particles, and the likes.

It is the most difficult scum to remove and it also brings the most risk to the user. This scum is usually caused by a damaged or worn-out filter.

Can You Use a Hot Tub With Scum?

While hot tub scum is just oily grime that floats in your water, it’s still not recommended to use a hot tub with scum water. One of the hot tub scum causes is the unbalanced water chemistry levels. And, dipping in water with high or low pH isn’t recommended.

It takes less than 24 hours to fully get rid of hot tub scum. So, clean the hot tub first and then use it. So how do you get rid of hot tub scum? Let’s find out.

How to Remove Brown Hot Tub Scum?

How to Remove Brown Hot Tub Scum?

Getting rid of brown hot tub scum isn’t difficult. Since brown scum is usually caused by a high ph level, the best thing to do is to reduce the ph level of the water or balance the water chemistry. Let’s check out how to get rid of brown scum.

1. Use Water Clarifier

Water clarifiers will help to break down the scum so it is easier to clean. You might also be lucky enough that the water clarifier will resolve the brown scum problem.

2. Use a Floating Sponge or Hot Tub Cleaning Net

The next thing to do is to use a floating sponge or a hot tub cleaning net. Floating sponges are usually just placed on the water in the hot tub. The floating sponge will absorb things like body oils, body care products, and other liquids in the water.

Just place the sponge on the water and leave it for a few hours. It will be easier for the sponge to absorb the scum since you have used a water clarifier to dissolve it. The cleaning net can be used to scoop and dispose of the brown scum from the surface of the water.

3. Balance the Water Chemistry

After removing the brown scum, you should balance the water chemistry. You can first take a sample of the water and test it to know the ph level. After that, you can use ph decreaser or ph increaser to balance the water chemistry.

How to Get Rid of Green Hot Tub Scum?

How to Get Rid of Green Hot Tub Scum?

Green hot tub scum is also easy to remove. But, you should know that you can’t completely remove metals from your water because the water you put in the hot tub already comes with metals.

1. Use Metal Sequestrant

Metal sequestration is a process that keeps the metal substances in your water solidified. This makes it easier to remove the metals since they are clogged together by the sequestrant.

2. Use a Hot Tub Net

The next thing to do is to use a hot tub net to scoop out the solidified metals from the surface of the water. This will remove the bulk of the green hot tub scum. This will help if you already have the green scum in your water.

If you don’t and you are worried about metals building up in your hot tub, you can use a pre-filter or a hose filter while filling the hot tub. The hose will filter the bulk of the metals and other substances out of the water that goes into the tub.

How to Get Rid of Blue-green Scum?

How to Fix Blue-green Scum?

Getting rid of blue-green hot tub scum will take a combination of different methods since the scum is caused by many factors too.

1. Use a Net to Scoop Out the Blue-green Scum

The first thing to do is to use a net to scoop out the scum on the surface of the water. This would not remove all the blue-green scum but it will remove most of it.

2. Follow the Same Procedure for Removing the Green and Brown Scum

After scooping out the blue-green scum, you should also use the same procedure as stated above for removing the brown and green scum.

Start by using the water clarifier to dissolve the remaining scum in the water. Then use the metal sequestrant to get rid of the metal in the water. After doing these, you can use the net or a sponge to get rid of the reminding blue-green scum.

3. Clean It Repair the Hot Tub Filters

Blue-green hot tub scum is usually caused as a result of damaged or dirty filters. If the filters were working or clean, then you wouldn’t have as much scum. Switch off the hot tub and remove the filters. Then clean them and let them dry. If the filters are damaged, you should repair or replace them.

4. Drain the Tub

A good idea after removing any type of hot tub scum is to drain and clean the tub. If you notice scum in the water, then the water is no longer safe for you regardless of if you remove the scum or not. So after removing the scum, drain the water and clean the hot tub before refilling it.

The steps above will help you get rid of hot tub scum. But how do you prevent hot tub scum from forming in the first place?

How to Prevent Hot Tub Scum?

The following practices will help you prevent hot tub scum.

Shower Before Entering the Tub

You should always take a shower before entering the hot tub. This helps to reduce the amount of body care products and bodily residue that get into the water.

Don’t Eat or Drink in the Tub

Try not to eat or drink anything inside the hot tub and if you must, do so outside the hot tub. This will help to prevent hot tub scum.

Shock the Water Regularly

Shocking the water regularly helps to clean the water. Hot tub shocks such as non-chlorine shock have specific ways of adding them to the water.

So, ensure to follow all the instructions stated by the manufacturer. Using too many chemicals will over-shock the water and that can lead to a high ph level that can also cause brown scum again.

Clean the Filters

Ensure to always clean the hot tub filters. If the hot tub filters are clean, you wouldn’t need to worry too much about hot tub scum. But, if the hot tub filter isn’t clean or not working properly then you should replace them as soon as possible.

Change the Water Regularly

Ensure to change the water in your hot tub as at when due. You should also drain and clean the hot tub before refilling it.

Use Hot Tub Scum Balls

You can always leave floating sponges on the surface of the water. These floating sponges are usually called hot tub scum balls.

Hot tub scum balls aren’t costly and there are even products that add decor and style to the hot tub.  They will reduce the “ring around the spa” (a.k.a hot tub scum) by absorbing oils and other liquids in the water.

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