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Pool Troubleshooting: Metals & Staining

How do I know if I have metals in my pool?

Stains and discolored water are generally caused by either organic materials (leaves, algae, phosphates, etc) or metals in the water such as iron or copper. Before you can properly treat the problem, you will need to find out what is causing the discoloration or staining.

When you fill up your swimming pool, your water source can contain levels of heavy metals such as copper, iron, silver, magnesium, etc. This is especially common if you are filling the pool with well water. When you add chlorine or shock, the metals are oxidized and can change the color of your pool water and can cause staining to the pool surfaces. 

Depending on the metal content of your pool water, you may notice your pool changing color to green (copper), brown or rust color (iron), black (silver), purple (manganese or magnesium) etc. 

How to tell if pool discoloration is caused by organic contaminants or from metals?

2 methods of testing for metal staining:

1. Ascorbic Acid

 You can test with ascorbic acid (or a vitamin c tablet) on the stained area. Rub the ascorbic acid on a stained area. If the stain comes out then it is a metal stain. If not, it could be alage or other organic matter causing the stains.

2. Chlorine tablet test (trichlor)

You can instead test the area with a trichlor chlorine tablet. Place the chlorine on the stained area for a few minutes. If the stain lightens then the stain is being caused by organic staining, not metals. If your staining is being caused by algae or other organic sources check our guide for removing algae here.

(Disclaimer: Please use caution as these processes may bleach out colored pool surfaces.)

Now that you have determined that the stain is in fact caused by metals, how do you actually remove the metals in your pool?

Removing metal stains in swimming pool

Products needed:


Pool metal stain remover kit bundle


Metal staining treatment steps:

1. Add BioGuard Pool Magnet Plus to swimming pool water (Use chart below for correct dosage amount for your pool size.)

2. Add BioGuard Sparkle Up Filter Aid directly into the skimmer according to label instructions for your filter type and size.

3. Backwash 24 hours after applying Sparkle Up.

4. Clean metals from your filter with BioGuard Kleen It Filter Cleaner. Follow instructions on label for your pool filter type and size.

How to remove metals and stains from swimming pool water


Metal removal fast-fix kit for swimming pool water


How to fix copper, iron, silver, magnesium staining in swimming pool

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