Iron and how it affects pool water
A common mineral in H 2 0, iron can stain your pool’s water, giving it a red or green tint, or blackening its appearance. Other factors that contribute to iron staining are erosion from pool equipment, chlorine and low pH levels. You can see brownish stains on the walls of your pool, on pool toys, and on the sides of your pool and spa, if the problem gets bad enough. Iron in the water can build up until it stains the plaster walls, which reduces water clarity and can be unhealthy.
If you suspect that you have too much iron in your pool water, you can use an iron test kit or take a sample of water to your local pool supply store for testing. Your sample should have no more than 0.2 parts per million of iron. If you have more than that, you can resolve the problem by using an iron removal treatment.
One method is to “shock” your pool and follow up with a treatment of clarifier. Then you should brush the sides and bottom of the pool and run the filter for several hours.