Hot Tub Water Green – We Have The Simplest Solution


Several different factors might cause hot tub water green problems. If you have one, you should know that you’re not alone – it is a very common issue for a lot of hot tub owners. Usually, a chemical imbalance in the water might be a problem, but green hot tub water might also be caused by other things – such as algae. However, algae are usually not the main cause and you don’t have to worry about it too much

Still, there are a few things you should know about maintaining your hot tub so you don’t have to deal with green water.  In this article, we will try to help you understand what is causing the discoloration and what you can do to prevent it.

Common Causes

These are some of the most common causes of hot tub water green issues:

  • Excessive metal content
  • Algae
  • Low pH
  • Low sanitizer levels

Excessive Metal Content

Excessive metal content is one of the more common causes of green hot tub water. Water that is kept in the municipal system or wells usually have high metal levels – iron and copper are the most prevalent.

The water will turn green if you shock the hot tub. Shocking the hot tub will trigger the oxidization process, which will then cause copper to react and become green.

The simplest way you can tell whether the excessive metal content is the cause of the green water inside your hot tub is to check pH and TA levels. If these are in balance, the water in the hot tub should just have a green tint. For example, imagine you added food coloring to the water, the result should be similar. The water table can be affected by the temperature too – which can cause metals to become more evident.

Removing Excessive Metals

Follow these steps to quickly get rid of the green water in the hot tub:

1. Test calcium hardness, pH, and total alkalinity and adjust to normal levels.

2. Get a natural stain remover and add about 1.5 tablespoons per 500 gallons. You might notice an immediate amelioration after this step.

3. Re-check your metal eliminator filter if you have one. This is also a preventative step to remove the green water.

4. Check the levels of the chemicals once more, including sanitizer. Adjust accordingly.


Your water source probably won’t change, so you might have to deal with green hot tub water again. This is why you should take preventative steps:

1. Refill – get an end filter for your hose to reduce metal impurities.

2. Remove – use a metal remover product. You can usually buy these in a bottle and they will help you remove some of the metals that cause stains (copper included).

3. Prevent – use a natural clarifier at least once a week just as a safety measure.

4. Shock – To maintain healthy water in your hot tub, make sure you add a non-chlorine shock after each use.


If your hot tub cover is left off or removed during the day algae can spread very quickly. Also, if the sanitizer levels are consistently low and your filter cartridge is dirty you can expect that you will have to deal with hot tub green water problems. But, how can you know whether the algae are causing the green water?

You will most likely notice a slimy coating inside the hot tub if the algae growth is present. Algae can also have many different colors like mustard or black. Just keep in mind that a slippery feeling on your feet while you’re inside the hot tub probably means that there are algae. Bathing suits are the most common cause for algae which is why you need to be sure that your swimwear is clean after using it (just wash it). Especially if you take a bath in the ocean, a river, or a lake.

Removing Algae

The minor algae growth can be managed without too much hassle. Get yourself an algaecide and put a dose in your hot tub water if you don’t think algae has spread too much. You should notice an improvement shortly after.

Use the same fluid at least once a week for preventative measures. Just add about 2 ounces per 500 gallons of water once per week. Also, make sure you follow the instructions and directions given on the bottle to fight off the green hot tub water.

When it comes to heavy algae growth, you will have to take a few extra steps:

1. Plumbing – Use a flush product to get rid of the algae if you think it is hidden in the plumbing. If this is causing the water to turn green, the algae will return even after you’re done with cleaning and refilling.

2. Shell  – Use a non-foaming cleanser to clean the inside of your hot tub after you draining and using a flush product. Vinegar, bleach, and other household hot tub cleaners are not recommended. All of these products may alter water chemistry and damage the hot tub shell.

3. Filter – Replace the filter cartridge if it is old, or just perform a deep clean on it. Also, pay attention to your antimicrobial filters and whether they are functioning. These have better filter media that will stop bacteria growth.

4. Refill – Refill the hot tub only after you are done with all of the steps above.

5. Balance – Test for the pH levels and total alkalinity. Adjust accordingly to normal levels.

6. Prevent – As mentioned above, use an algaecide to prevent hot tub green water problems from coming back.

Low pH Levels

  1. Test the pH levels and total alkalinity.
  2. Start by adjusting the alkalinity first. You will regulate pH levels easier if you adjust the total alkalinity levels first. Use a pH booster if the pH levels are low but the TA is normal. These products will help you increase the pH levels without changing the TA levels.
  3. Do the water tests again to check the chemistry levels once again. Adjust accordingly.
  4. Do these tests at least once a week to make sure that the chemistry is right.
  5. Once you’re sure that pH levels are in balance follow the above-mentioned directions for removing excessive metal content to get rid of the green tint in the water.

The main point here is to balance TA and pH. pH is directly impacted by the alkalinity in the water. pH bounce can seem impossible to control when TA is low. On the other side, if the TA is too high, you might have difficulties with lowering the pH levels.

One thing you need to keep doing over and over again is to retest the chemistry levels in your hot tub at least once a week. Also, keep your sanitizer and hot tub water regulated and you should be able to lower the risk of hot tub water green issues. Also, do the draining at least 4-5 times a year (even more frequently if it is needed). This will help you to keep the water as healthy as possible.

Low sanitizer levels

Proper sanitizer levels should be maintained at all times. However, life just happens and sometimes the proper maintenance can’t be done even for months. Whether you use chlorine, bromine, or any other sanitizer, not shocking frequently or low sanitizer levels may be causing green hot tub water.

Shocking will allow your sanitizer to perform as it should. Optimally, you will be adding the sanitizer after each use or at least once a week. The green cloudy hot tub water is usually the best sign that you’re dealing with low sanitizer levels.

Raising low sanitizer levels

1. Start by testing the sanitizer levels.

2. Adjust accordingly so the levels meet the recommended amount – depending on the sanitizer used.

3. Give the water 24 hours before your retest for the sanitizer levels and adjust again if needed.

4. Do tests at least once a week to properly maintain your hot tub.


Q: Is green hot tub water safe?


It is not necessarily safe, but there aren’t many harmful effects either. Still, it is not recommended to get in a hot tub with green water since the green color is an indicator of the chemical imbalance or presence of algae. These can lead to complications if you ignore them.

Globo Surf Overview

To recap – there are a lot of different causes for the green water in your hot tub. You will be able to find the real cause and deal with the issue on your own. The presence of algae will be followed by a slimy structure on the shell of your hot tub, while excessive metal content will give the green tint color to the water. Cleaning your hot tub regularly is also very important to maintain a healthy environment in your hot tub.

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Globo Surf
My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!