For most pools, surface discoloration is caused by either algae or metals. A variety of metals such as iron and copper can be present in the fill water, and of course, copper is a common ingredient of algaecides. As metals are oxidized, they become insoluble and form stains on the pool surfaces, much like the iron stains sometimes seen in bath fixtures and associated with well water. The first thing to do is make sure you have stains and not algae. If the color brushes off partially or completely, it's algae.
If it's a stain, follow these steps:
- Check the pool water balance. Collect a sample of water and see your Sustain Authorized Dealer. If possible, test the hardness, total alkalinity, pH and cyanuric acid yourself. Unless you're using a copper-based algaecide or adding well-water to your pool, the stains are due to the water becoming aggressive or corrosive. Have your water tested for the presence of metals.
- The first thing you'll add to your pool water is a good sequesterant or chelating agent, available at your Sustain Authorized Dealer. Use of a metal remover product will prevent more staining and help transfer the metals that have deposited on the pool surfaces to the filter media.
- Continuous circulation is important during this stain removal process. Remember that brushing the stains is necessary to help remove them. (In extreme cases, direct application of acid may be necessary, but leave this to the professionals.
- While the pool is circulating, you'll want to bring the water back into balance. As you increase pH and alkalinity, do it slowly to minimize the staining that can occur.
- After the stain is removed and the water is properly balanced, backwash your filter, or if you have a cartridge filter, clean the filter element to ensure the removal of any metals that may have collected there.
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