Why Is My Hot Tub Water Slightly Green?
A hot tub provides a comfortable escape throughout the year, whether it be in the spring, summer, or fall. That said, nobody wants to get into a hot tub if the water doesn’t look welcoming. So, why is my hot tub water slightly green?
If your hot tub water is slightly green, it’s most likely because algae is growing. You can kill algae if you shock the water to increase the chlorine levels and prevent further algae blooms. Otherwise, there may be excessive minerals, like iron, in the water due to plumbing corrosion. Green water is also common if you have hard water.
Treat your hot tub water weekly to maintain alkalinity and prevent algae growth. Otherwise, you risk skin irritation and rashes that may require medical attention. Follow along as we explore why your hot tub water is green, and highlight easy fixes.
What Causes Green Hot Tub Water?
Poor maintenance is typically the main cause of green hot tub water. Many homeowners add chlorine to their hot tubs every few days to maintain a healthy and clean balance. However, the chlorine requirements vary depending on how often you use your hot tub.
You should at least treat your hot tub with chemicals once per week. Low chlorine levels cause bacteria and microorganisms to run rampant in a hot tub. Not only can this explain why the water is slightly green, but it’s also means the water is unhealthy.
To avoid this problem, keep the chlorine level in your hot tub between 3 and 5 parts per million. Otherwise, a biofilm can form in your hot tub that will get worse with time if you don’t treat the water.
High Mineral Content
Green hot tub water doesn’t always indicate unhealthy bacteria and algae. In some cases, hot tub water can become green because the mineral count is too high. Minerals from metals like copper and iron, can enter the water because of corrosion from your hot tub’s plumbing.
This can also occur if you live in an area with hard water due to excessive minerals in the supply. You can tell that minerals are the problem if you test the water chemistry, and it appears to be normal. To fix the problem, you must first shock the water.
Next, you must check for mineral sediment in your hot tub and suck it up with a vacuum. Drain at least ¼ of the water in your hot tub, refill it, and treat it with a mineral sanitizer. Keep in mind that you may need to drain ½ of the water or more, refill it, and treat it if the problem persists.
Algae Growth
Algae growth is the most common reason for green water in a hot tub. This is a common problem in hot tubs with a low chlorine or bromine count, leaving the water susceptible to algae. You can typically fix this problem if you dose the water with 50 grams of chlorine or more depending on tub size.
This will raise the chlorine level to double the recommended level, which is necessary to kill algae and bacteria. Leave the cover off of the hot tub to avoid damaging it with chlorine, and let it sit for a few hours. If the algae is stubborn, it’s worth draining the water, refilling the tub, and shocking it with 50 grams of chlorine again.
You may also need to flush the pipes with chlorine. That’s because algae sometimes remain in the pipes and continue to tint the water green. Repeat this process until the water is clear, but don’t get in until the level is 3-5 parts per million.
How to Prevent Green Hot Tub Water
Maintenance is the easiest way to prevent green hot tub water. However, you can take a few specific steps to make this much easier, such as:
1. Keep It Covered
Keep your hot tub covered most of the time when you aren’t using it. You should only uncover your hot tub when you use it or if you just treated the water with high does of chlorine. When left uncovered, a hot tub becomes vulnerable to bacteria and debris that can negatively impact the water chemistry.
Covering your hot tub can also reduce the water evaporation rate, which can help save water. Doing so can also help your hot tub retain heat, which saves energy. It’s also important to cover your hot tub if you have small children and pets that could accidentally enter it.
2. Deep Clean Your Hot Tub
While you must treat the water weekly, you only need to deep clean your hot tub a few times a year. That is enough to keep the water free of bacteria, algae, and sediment if you continually treat the water. To deep clean a hot tub, you must first drain the water to easily access the components.
Next, you must remove the filter (or filters) and clean it with water and white vinegar or dish soap. Use a hot tub cleaning solution to thoroughly scrub and clean the tub and jets. Scrub the outside of the tub, including the cover, as well.
Rise your hot tub out and scrub it to remove any remaining chemicals and grime. Refill your hot tub with clean water and treat it with chlorine when it’s full. You only need to perform this process 3-4 times per year.
3. Routinely Test And Clean The Water
It’s easy to wind up with green hot tub water if you don’t test it regularly. That’s the only way to know that there is an imbalance before it’s too late. Keep several test strips at home, so you never run out on short notice.
Test the water at least twice per week if you regularly use your hot tub. You must test the water’s chlorine and alkalinity. Alkalinity imbalances can throw off the water’s chemistry and cause corrosion, which can cause green water.
Treat the water with chlorine if the level is outside of the 3-5 parts per million range. Keep in mind that it’s dangerous to get in a hot tub if the chlorine level is higher than 5 parts per million. Let the chlorine level fade before you get in a hot tub after it's been shocked.
Is Green Hot Tub Water Dangerous?
Green hot tub water can become dangerous if you don’t act quickly and treat it. For example, the presence of algae and harmful bacteria in hot tub water can cause waterborne illnesses. You may experience nausea, diarrhea, eye irritation, and skin rashes depending on how much exposure you get.
The chlorine in your hot tub can eventually become much less effective if your hot tub has green water. That is the case if a biofilm forms and obstructs the equipment, such as the pump and filter. This will quickly make the problem worse if you fail to treat your hot tub with chemicals.
Bacteria will continue to thrive until you treat the water with chlorine or bromine and clean the filter. Wait to return to your hot tub until you test the water and are sure the water chemistry is safe.
Summing It Up
Your hot tub water is most likely green because of algae, and you must treat it with a high dose of chlorine. Treat the water with 50 grams of chlorine per 1,000 liters of water to kill the algae. Otherwise, the green tint may indicate excessive minerals in the water due to hard water or corrosion. In that case, you must drain, clean, and refill the tub.
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Nick Durante is a professional writer with a primary focus on home improvement. When he is not writing about home improvement or taking on projects around the house, he likes to read and create art. He is always looking towards the newest trends in home improvement.
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