When treating a hot tub, one of the most common issues is discolored water, which can range from a common yellow or green to even brown, orange or black.
Too often, people in the industry, from brand-new employees to seasoned veterans, are unaware of the cause of the colored water, incorrectly believing it is an algae issue.
What causes colored water?
Spa water that is clear but exhibits color is a naturally occurring phenomenon that’s caused by metals in the water — typically iron, manganese and copper — that are oxidizing (rusting). The colored water is not harmful; it just looks odd.
Rusting will speed up if metal is exposed to an oxidizer, which is why customers may see water change color when they add chlorine, bromine or nonchlorine shock to the water.
How do you clear colored water?
To clear colored water, shock it by adding granular chlorine or bromine at 1 ounce per 250 gallons of water. You may also use spa shock as per the directions on the package. Wait a minimum of 24 hours, and if the color persists, shock the water again and wait at least another 24 hours. Multiple applications may be required.
Sometimes when the shock is added, the color may become more intense, often right before your eyes as the metals begin to further rust. If this happens, wait 24 hours, and you’ll find the color will be greatly reduced, if not cleared completely.
How do you prevent colored water from occurring?
Adding fresh water to your spa will introduce more metals to the spa water, and you may experience colored water again.
Seasoned spa owners often comment that they have not seen colored water in the past and wonder why it suddenly happens. The most common reasons are:
- Water can change in composition over time. The volume of precipitation and even subtle seismic activity can contribute to the concentration of metals in the water.
- When municipalities flush fire hydrants, cavitation occurs, which can loosen iron in old cast-iron water mains, introducing metals to the water supply. If fire hydrants are being flushed upstream from where a spa is being filled, the tap water may have higher levels of metals in it that day.
To help reduce the number of metals in the water, you can use a metal-removing product, fill your spa with soft water (then harden it with calcium hardness increaser after filling) and use a premium hose prefilter such as the X10 Water Filter.