Spa and Hot Tub Water Color Problems

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hot tub water color problems

We've all been there before, when you lift the spa cover to discover a color other than clear blue. Hot tub water can be all colors of the rainbow when conditions aren't right. Yellow, brown, green, white and every shade in between.

Today, we'll discuss how to identify and troubleshoot colored spa water so you can restore your clear, sparkling blue spa water. It doesn't matter what type or size of hot tub you have, even if your tub is as big as a pool. You can still use these tips to fix colored hot tub water.

After you've spent several months (or years!) taking care of your spa, your trained eye can tell right away when something's not right. It's a bit less sparkly and translucent, and a bit more dull and dirty looking. Or perhaps the water has turned one of these strange spa water colors.



When your spa has a shade of green, you may immediately think of algae. If your sanitizer has been low or your filter cartridge is dirty, it very well could be algae. Touch the sides of the spa, and if it feels slimy, you can bet you have a small algae bloom on your hands. Algae can grow even under a spa cover, in the dark, hot water. To treat a hot tub for algae, check and balance the pH and alkalinity, and add a shock treatment. After filtering out dead algae, it's always recommended to replace the spa cartridge with a new one.

Green hot tub water can also be caused by a mineral we know as copper. It can enter the water from copper pipes carrying fill water, or it can come from natural well water. It can also come from copper heat exchangers used in gas-fired spa heaters, or it can come from using copper pool algaecide in a spa (not recommended). This is the same copper that can turn a swimmer's hair green. The water can be clear and bright green, without slime on the surfaces. Control  copper in your hot tub water with a product like Metal Gon or CuLator packets.



Yellow algae is a particularly resistant type of algae that can exist in a dark heated hot tub, even in the presence of normal bromine or chlorine levels. It seeks out small, out-of-the-way crevices, and when in full bloom, it will deposit itself in sheets across spa surfaces. Treatment for yellow algae is to use a very high level of chlorine spa shock. Balance the water first, and turn off the heater before shocking the spa. Allow the water to circulate for several hours, with the cover removed. If the level drops to zero within 24 hours, shock the spa again, until it holds the chlorine level. After this shock treatment, drain and scrub the spa, bleach wash the spa cover and replace the spa filter with a new cartridge.

Yellow hot tub water can also come from an excess of pollen in the springtime, especially if you have left the spa cover for some time. Iron oxides in well water can also impart a yellowish color to the water, especially if the spa turned yellow after shocking. If you are on a well water system, use a pre-filter to remove all minerals from your fill water. Finally, if your bromine level is extremely high, the water can take on a yellow-red color, especially in the presence of low pH. Don't enter a spa if the bromine residual is over 5 ppm.



Brown water is not the most appetizing hot tub water color. If your spa has suddenly turned brown, much like the color of tea, again you can usually find the problem to be high levels of minerals, namely iron oxide. This may occur within hours after shocking the spa or making big pH adjustments. The filter cartridge should remove some of it, but to clear it up faster, you can force it back into solution with a sequestering agent like Metal Gon.

Brown spa water also occurs from contaminated fill water. During dry, hot periods, some municipal water supplies begin scraping the bottom of the barrel, which adds a lot of particulate matter to the water supply. You can combat this by using a pre-filter on your hose when you fill the spa. This simple tool will remove even microscopic particles from your fill water.



Milky hot tub water, which is so cloudy that the water appears white, can come from many causes. High calcium or alkalinity, ineffective filtering or pumping, or air in the system causing micro-bubbles - all of these can make hot tub water appear white-ish. Contaminants from body lotions, cosmetics and hair products can also change the water color from clear blue to white. If your spa has cloudy water, here's a troubleshooting blog post with 10 reasons why.

White hot tub water can also be infected with white mold, a type of bacteria that grows in small clumps and clusters. In spas that have not been maintained properly, this type of slime can be difficult to remove, but can be treated effectively with raising chlorine level to 30 ppm, running the spa for several hours and then draining. Replace the spa filter, and rinse all removable items like spa pillows, nets, baskets and thermometer in a strong bleach solution. Use a biofilm remover like Jet Clean to clean out the pipes.



Pink algae is a close cousin of white water mold discussed above. Not actually an algae, it's a form of bacteria, although it displays characteristics of an algae.  Pink spa water is not a very common color for spa water, and pink algae won't actually color the spa water pink, except in very mature colonies. Treatment for pink algae is similar to white mold above. It's not easy to eradicate, as it is able to tuck away cells that are difficult to reach - but it can be eradicated, by hitting it hard with shock (over 30 ppm), and using a purge product to clean the lines and crevices. Be sure to replace your spa filter, and soak all spa items in a strong bleach solution before refilling the spa.

Don't let colored hot tub water get you down! There's always a solution...