Is Your Hot Tub Water Green? What’s Wrong and How to Fix It

green hot tub water

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What can turn your hot tub experience from oohs and ahhs to OH and EW? Green water.

Hot tubs require regular  maintenance to keep the water crystal clear and feeling soft. But even the most diligent owners might feel flustered when they discover the water has a green tint. After all, green water does not scream relaxing. More like, “FIX ME!”

But how do you fix green hot tub water? It might be easier than you think.

Green Hot Tub Water Causes

What’s behind your green hot tub water? There are a few things that can turn your water an unsightly color.

Minerals. High levels of iron or copper can turn the water green. How does that happen? Oxidation. The minerals in the water interact with the other chemicals in the hot tub and cause it to turn green. You can use a water quality strip that tests for copper, which can often be found in your source water.

Low levels of sanitizer. If you are frequently using your hot tub or missed some regular maintenance, you might need to test for chlorine.  Check your owner’s manual to see the recommended chlorine levels for your hot tub. Typically, it should be between 2 and 4 parts per million. Other sanitizers, like bromine or salt systems, will require different treatment. 

Total alkalinity. If your water is green and cloudy, total alkalinity could be to blame. Test your hot tub water to see if the chemicals are balanced. While the recommended levels might vary between hot tub brands, you should use a pH increaser until your total alkalinity is between 80 and 150 ppm.

Pollen. A less likely culprit, pollen could be a problem in the spring — especially if you leave your spa uncovered. Pollen can collect in the water, causing it to turn green (or yellow).

green hot tub water
If you are concerned about green hot tub water, add a sequestering agent. Sometimes high levels of iron and copper can t urn the water green.

Green Water Fixes

Minerals. If you suspect that iron and copper are responsible for your green hot tub water, you will want to add a sequestering agent. Wait at least 30 minutes for the agent to circulate through the filter and components of the spa. 

Sanitizer. If your sanitizer levels are low, you will need to “shock” your hot tub water. A non-chlorine shock made for hot tubs should be sprinkled over the surface of the water while the jets are on. Be sure to read the package directions for the non-chlorine shock that you use.

Pollen. Pollen will typically float to the top of the hot tub water, making it removable with a skimmer. But, it might also get caught in your hot tub filter. Rinse your hot tub filter according to the manufacturer’s directions and give the water time to cycle through once replacing the filter. Be sure to address any other potential water chemistry issues. 

Drain the hot tub. Most hot tub owners should drain their hot tub every six months. However, if your water is not clearing up, it can be a way to rid the spa of green water. It’s also a good idea to take this time to clean your hot tub filters, which will help keep the water clean. When it is time to fill your hot tub, be sure to use a pre-filter. A pre-filter will remove heavy metals and suspended solids in your source water.