What Color Should Hot Tub Water Be? (Simple Ways to Make It Clear!)

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What Color Should Hot Tub Water Be?

If you have had a hot tub for some time you have a fair idea how the water in the hot tub looks. Especially, after you have drained the hot tub, scrubbed it clean and filled it with fresh water. But the color of the hot tub water is not always the same. So what color should hot tub water be?

Clear. Ideally the color of the hot tub water should be clear. Crystal Clear. Because that is the color of pure, clean, uncontaminated water.

What color should hot tub water be?

However, I must admit a lot of people associate the color of water, even pure, clean water with “clear blue”. And they are not wrong!

Is pure water really clear? Not really—even pure water is not colorless, but has a slight blue tint to it.


The scientific reason is that water molecules absorb most wavelengths of light, but reflect the shorter wavelength of blue light. This is the reason the ocean appears blue.

However, the color we see does depend on the volume of water. Pure drinking water in a glass or bottle appears clear & colorless. Because the volume is small.

The volume of water in a hot tub is not substantial. So if the water in the hot tub is totally pure & uncontaminated, it should appear pretty much clear. OK, maybe with a hint of a tint of blue! 

As a hot tub owner you need to be aware of the different colors hot tub water can be, the reasons behind it and what you need to do to make your hot tub water crystal clear again.

You can use the “cheat sheet” below or read the entire post for full details and links to recommended products.

Hot Tub Water Color

Why Is My Hot Tub Water Blue? 

At times you may feel that the color of your hot tub water is more blue than just a slight hint of blue.


A blue color tint in hot tub water is the result of high copper content. The recommended copper content is 0.2–0.4 ppm. Check the copper content with a water testing kit.


Sometimes the copper content in the hot tub water can be high, if the ionizer setting is too high. So you’ll need to turn down the ionizer setting. This will typically work when the copper content is in the 0.4–1.0 ppm range.

In case the copper contact is higher than 1.0 ppm then you will need to add a sequestering agent to the water.

In case you continue to have this problem on a long term basis then the copper may be coming from the water source as well. Check that. If high, you should use a metal trap pre-filter that can be attached to the garden hose.

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Why Is My Hot Tub Water Green? 


A green tint in the color of your hot tub water is an indication that there may be some algae growth.

However, if the walls of the hot tub are not slimy, then the green color may be from an increase in levels of copper or manganese, rather than algae.


Shocking your hot tub and cleaning the filter are the first steps you must take, when you notice that the color of your hot tub water is turning green.

If the above does not solve the problem, test the water for metal content. If copper or manganese levels are high, then use a sequestering agent.

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Why Is My Hot Tub Water Yellow? 


Not all algae are green, some are yellow too! If your hot tub water has a yellow tint, it could be an indicator of yellow algae growth. You will know it is algae if the sides of your hot tub are slimy.

High iron content in the water can also result in yellow color. The yellow color comes from iron oxide. The source of high iron could very well be the water source itself.

In case you use bromine in your hot tub, then extremely high bromine levels can also turn the water somewhat yellow.

Highly unlikely but sometimes a lot of pollen in the air can make the water look yellow especially, if you have not been using the hot tub cover.


First things first. Check the water chemistry. Make sure that iron content and bromine levels are within the recommended range, using a water testing kit.

Shocking the hot tub will eradicate the yellow algae growth. 

To bring the high iron content to recommended levels, use a sequestering agent. If you think that the iron is coming from the water source, then use a metal trap pre-filter that can be attached to the garden hose, when you fill up your hot tub.

The yellow color from pollen in the air will disappear after a while. The filter will clean it out. But do remember to cover your hot tub when not in use, so that there is no more pollen addition.

If bromine levels are higher than 5.0 ppm you should not be using the hot tub. Just wait it out and in time the bromine levels will fall to recommended levels of 1–3 ppm.

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Why Is My Hot Tub Water Brown? 


Hot tub water can turn slightly brown when the iron content is high. The brown color comes from iron oxide. If you are using ground water to fill your hot tub then that may be the source of high iron content.


You will need to use a sequestering agent to neutralize the iron. Of course, this also reduces the levels of other metals such as copper and manganese.

In case the problem of brown water is long standing, then you must check the iron content as well as the contamination levels of the water source. If it is high, you will need to use metal trap pre-filter attachment on your garden hose, when filling up the hot tub.

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Why Is My Hot Tub Water White?

You may sometimes find that your hot tub water has turned milky. This is not the same as the white color from the bubbles that is normal.


Excess of contaminants, such as lotions, cosmetics, hair products, etc. from hot tub users can cause the hot tub water to turn milky white.

High calcium content or high total alkalinity is another reason the hot tub water turns milky. The color comes from fine particles of calcium suspended in the water.

Air in the internal spa system can result in the formation of microbubbles which give the water a milky color.

If the hot tub filtration system is not working properly, then fine dust and dirt particles will not get filtered out. They will start accumulating in the hot tub water, giving it a whitish color.

Hot tubs can also see the growth of white mold, if you have been lax on sanitizing or shocking the hot tub.


It is best to go for a multi prong solution. This involves super chlorination and running the hot tub for several hours. Follow this by clearing out the jets and draining the water. 

Check the condition of the filter. Either give it a thorough cleaning or better still, replace it.

Make sure that the calcium hardness of the freshwater is not too high.

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Why Is My Hot Tub Water Pink?


The pink color of the hot tub water is the result of pink algae growth. Pink algae is closely related to white mold. In fact, pink algae is a type of bacteria. 


It is relatively easy to get rid of pink algae, because it just floats on the surface. Shocking the hot tub will kill it. Clean out or replace the hot tub filter after this operation.

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Why Is My Hot Tub Water Gray? 


The hot tub water can turn gray or black, if algae, mold and mildew grow in it simultaneously.


Shock is the best way to treat any growth of pathogens. You may want to drain out the water after the shock treatment. Refill the hot tub with fresh, clean water.

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Thank you very much for reading the post. I do hope you found it informative and helpful.

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