This question comes up every summer. Swimmers and spa goers complain that the chlorine in the pool or spa has caused
their hair to turn green. The short answer is: Its NOT the chlorine, its the copper.
A simple explanation: Chlorine after all, is a bleach. When you add laundry bleach to the washing machine, it makes
clothes whiter, removes discoloration and stains, and kills organisms it does not make your clothes green, blue, turquoise
or any other color. Any amount of chlorine in water more than about 15 ppm (parts per million) starts the bleaching
process. Although typically a load of laundry in a washing machine has about 600 ppm of chlorine.
If it is the copper, where does the copper come from?
Copper can get into the pool or spa a number of different ways. First, drinking water (source or tap water) has a small
amount of copper in it already. So each time makeup water is added due to evaporation, a little more copper is added. Since
copper does not biodegrade or go away on its own, it builds up.
Second, some algaecides have as their active ingredient copper. The copper in algaecides usually has a special ingredient
added to it that prevents it from staining people and vessels. This ingredient is called a chelating agent (pronounced KEYlating)
and copper algaecides that have this ingredient are said to be chelated. However, sunlight, constant high levels of
chlorine or bromine, ozone, superchlorination and even non-chlorine shock treatments can oxidize the chelating agent.
Once this happens, the copper stain protecting ability is decreased.
A third way copper gets into the pool is from the equipment. Water that has a low pH actually dissolves a small portion of
the copper metal in components such as copper pipes, heater headers, heater heat sinks, bronze or brass pump parts such as
impellers or volute assemblies, and even metals used in the filters. This is called corrosion. This small amount of copper
gets dissolved from the equipment or components and then mixes with the main body of water in the pool or spa.
Another related way copper gets into the water is by water velocity through copper pipes and fittings. Water that is moving
faster than the recommended velocity through a pipe will erode the pipe. This happens when too large of a pump is used on
a system than it was designed for and sometimes when a solar water heating system is used for a pool or spa.
The final way that copper can get into the water also comes from the equipment but for a different reason. A common
practice is to chlorinate a pool by placing a trichlor tablet (trichloro-s-triazinetrione) into the pool or spa skimmer. Also,
some pool owners have placed bromine tablets in their skimmers. Water flowing over the tablet dissolves a small portion of
the tablet and carries it through the equipment and back to the pool or spa. Trichlor tablets have a very low pH of about 2.8
while bromine tablets are about 4.0. If enough of the tablet dissolves, the pH of the water flowing over the tablet acquires a
low pH too. We have seen pHs from 3.0 to 7.0 all of which can cause metal components to dissolve. Please note: Some
manufacturers have produced special trichlor tablets and sticks that are designed to placed in the skimmer. These products
will not be a problem if used properly.