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

green hot tub large

It’s bad news when the water in your hot tub is green. Is it algae? Or something worse? And is it bad to soak in? You’re probably wondering, how do I get rid of the green in my hot tub?

Having owned 4 tubs for over 15 years, here’s what I know:

A hot tub that is constantly green in color has algae and should be drained & refilled. The filters also need to be cleaned. But an algaecide can also be added. However, if the green color is only present briefly after adding sanitizer, the color is from iron or other metals in the water and is not an issue.

So if it is due to iron, can that damage your hot tub? And if it’s algae, what’s causing it?

Don’t worry. We’ll cover all that and more. And we’ll get deeper into the difference between metals in the water and algae so you can be sure of which one you’re seeing.

Read on to learn more about how to get rid of the green in your hot tub.

What does Hot Tub algae look like?

Hot tub algae can appear as green, yellow, blue, brown, or a combination of all of those colors. Its presence is also indicated by slime at the sides and bottom of the tub. It can also easily be stirred when moving a net through the water.

In addition to the slime, the sides and bottom of the hot tub would be slippery. Apart from the unhygienic state, this is a safety issue.

Algae is unpleasant to look at. It grosses one out.

But it’s not the sole reason that could give your tub water a greenish hue. If minerals are present in the tub, they will have the same effect.

But metals won’t look like particles in the water the way algae does. And iron in your water will only turn the water green for a max of about 30 minutes after you add chlorine or bromine.

But metals in the water can also be cause for concern.

In a recent article of mine, I explained what triggers the green in the hot tub water and how to get rid of iron. When iron and other minerals mix up with chlorine, the change can turn the water green, at least temporarily. But there is a long-term danger of high levels of metal in the water.

Just click the link to read it on my site.

How do I stop algae in my hot tub?

Keeping the hot tub’s cover in place and the water chemistry balanced is the best way to eliminate or prevent algae. But adding an algaecide to the water can also help keep the water clear.

Algae is caused by excess exposure to sunlight and possibly rain and will be most common in a hot tub that is not consistently covered. And it’s a frequent issue in pools.

Let’s check out these preventive measures in some detail.

Algae are bacteria that thrive in unhygienic environments. So, you want to keep your hot tub covered when not in use so that all manner of debris that could fall into it and become a host for algae don’t fall inside.

Water chemistry is arguably the most vital factor in ensuring that the growth of algae is inhibited in your hot tub. So, balance your pH, sanitize the water, and ensure the right level of alkalinity.

Your tub’s pH should be about 7.5 or close to it as much as possible. Sanitize with chlorine or bromine, as advised in the tub’s manual.

Naturally, you’ll test all three (pH, alkalinity, and sanitizer).

The filters can act as a path through which algae gets into the hot tub. So, ideally, they should be thoroughly washed every few weeks and deep cleaned each quarter.

The swimsuits and accessories should be washed and dried before they are used in the tub.

If they’re wet and kept in a damp place for long, they may become hosts to algae, and these could be unwittingly introduced into the tub.

CLICK HERE to check out Clorox Pool & Spa Green Algae Eliminator on Amazon.

It’s an awesome fast-acting algaecide that’s highly effective for preventing the growth of algae in your hot tub. It’s non-foaming and copper-free — so it won’t tint your hair green.

It’s got over 3,700 ratings on Amazon, and almost all are 5 stars.

Does iron in my hot tub water look green?

The presence of iron and other minerals in a hot tub can turn the water green, at least temporarily, when these mix with the chlorine or bromine applied to the water. But it should dissipate within 30 minutes of adding the chemicals.

Iron and other minerals occur naturally in water. It’s when they’re above the normal level that they alter the water’s color to green.

Iron is not harmful to you, but in addition to turning the water green temporarily, it will stain the surfaces of the tub.

Hot tub water that’s rich in iron and other metals becomes discolored but clear. However, you’ll notice that the surfaces of the tub are stained.

If the water is cloudy in addition to the above, then there’s a need to oxidize it. I explained how to oxidize the water in a recent article of mine.

By the way, oxidizing the water is the same as shocking it.

This can also help clear water that’s discolored because of the presence of iron and other metals. But aside from staining, high levels of metals in the water can also shorten the lifespan of the equipment over time.

Just click the link to read it on my site.

CLICK HERE to see Spa Choice Metal-Free on Amazon. It’s an easy way to get rid of iron in your hot tub water. But it will also help prevent or remove stains from metals too.

A non-toxic and non-phosphorus product. It may deplete your sanitizer level. So, you’ll need to test and balance your water.

It’s got over 180 ratings on Amazon, and almost all are 5 stars.

Is green water in the hot tub safe?

Green water caused by the presence of iron when it mixes with chlorine or bromine is safe to soak in. But green water can also be from the presence of algae, which is unsafe to soak in.

The presence of algae in your hot tub is a cause for concern.

Apart from the fact that a slimy sight is gross, it’s a danger to the tub’s users, seeing as slime is almost always slippery.

In fact, between 1990 and 2007, there was an increase of 160% in hot-tub-related injuries!

A well-maintained and safe hot tub has water that’s clean and clear. It may appear slightly blueish if your tub is deep.

Green water in your hot tub is a sign that the water chemistry is not balanced. So, sticking to a regular maintenance schedule is the way to go to really enjoy soaking’s sweet pleasures.

But if you do think the green is from the presence of metals in the water, which are not uncommon, there is a solution.

CLICK HERE to check out Leisure Time’s Metal Gon on Amazon. 

This not only gets rid of the metals in the water, but it helps prevent the staining of the acrylic shell too. And if some damage has already been done, it helps to get rid of that too!

How do I get my hot tub water clear again?

To clear dirty or green hot tub water, ideally drain, thoroughly clean, and refill. The filters should be washed or replaced also. But hyper-chlorinating the water with a double-dose of chlorine shock can also help clear hot tub water.

The first step is to test the water and note your reading. It serves as data reflecting the state of the water, and it can be a guide in the future.

The next step is to drain the water.

It’s got to go. After all, it is no longer hygienic. Then, clean the tub’s interior thoroughly using a disinfectant or bleach to ensure that you get rid of the algae. 

The slimy surface must be washed off so that it can no longer act as the host. Ensure that you also soak and wash the pillows, floaties… in a bleach solution.

Then, deep clean or replace the filter.

The filters trap the algae and then ensure it stays in the hot tub even after adding chlorine. Wash them very well. Better still, you could soak them in a chemical rinse. Alternatively, you could replace them if you’ve been using them for too long.

Now, refill the hot tub.

Wash the hot tub cover. The cover, not just the hot tub, is often a perfect source for algae to live. You want to also keep the cover very clean.

Use a diluted bleach mixture or a special vinyl cleaner like 303 Marine Protectant on Amazon. That way, you’re not unwittingly re-introducing algae even after you’ve washed the tub.

The cover is often a secondary home for microorganisms and bacteria.

After the steps above, shock the water. Wait a while, then shock it again. Of course, test the water chemistry before your next soaking session to make sure the levels have dropped down to normal. 

Being on top of the water chemistry is one of the best ways to reduce the incidence of your water turning green.


Green water in a hot tub can be a cause for concern, depending on what triggered it. We explored how to get rid of the green in a hot tub.

We learned that it’s caused by either algae or the presence of irons and minerals in the water when the latter mixes up with chlorine or bromine.

We looked at whether green water in a hot tub is safe. It’s not harmful if it’s caused by the presence of irons, but it can be harmful if it’s due to algae growth seeing as this makes the tub slimy and slippery!

We also checked out effective ways to get rid of discoloration and slime.

Photo which require attribution:

Mmmm, algae by Qfamily is licensed under CC2.0 and was cropped with a text overlay added

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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