Sequestering agents are commonly used in swimming pools to remove water hardness from metals and minerals. They combine with calcium and magnesium ions as well as other heavy metal ions in hard water such as iron and rust, to form molecules in which the ions are held so securely (sequestered) that they can no longer react with the water.
Why is a sequestering agent needed?
Rural water in the midwest (or well water) is usually very high in metals, however city water sources can also be high in these items as well. If the metals are not “sequestered” or coated, they will begin to oxidize quickly once they meet up with chlorine and or other sanitizers. This will cause a reaction which will more than likely turn your water brown, red, orange or green depending on the metal that has a high content in your water. By adding a sequestering agent, we can usually prevent this oxidization reaction from occurring.
When do I need to add a sequestering agent?
It is recommended to add a larger dose (usually 1 QT bottle at minimum) at the beginning of each swim season when the pool is first opened. In most circumstances, this will be enough to prevent the reaction from occurring. If your water source is high in metals, you may need to add a higher amount than that. The only other time you may need to add some additional sequestering agent would be after a heavy rainfall or when you are adding some additional water to the pool throughout the summer.
What about pool closing time?
Yes, we recommend to add some additional sequestering agent at the time you close the pool for the winter. This will prevent metals from coming out in the water and staining your pool surface or liner. This item usually comes in the Winter Closing Kits.
What do I do if my water has already turned colors due to the metals?
At this time, we will need to add a few additional chemicals to help reverse the effect. It can be a slow process and can sometimes be costly. The only surefire way to get rid of the problem without using additional chemicals is to drain the pool and start fresh. When you drain the pool and refill, it is important at that time to add the sequestering agent and give it 24 hrs to mix with the pool water (with the filter system running) before you add any additional chemicals. If you would like to treat the water instead of draining, a product called Ferri Iron Tabs can be added to help remove the color. This product along with your filtration system is what will reverse that effect. A sequestering will still need to be used even in this situation, to prevent it from re-occurring.