Prevention is the best strategy against pool stains

The causes of pool stains are no mystery: organic material, such as algae and tannins from plants, or inorganic material, such as metals, has become attached to the pool surface.

There is a lot of unsubstantiated information on the subject, particularly relating to metal stains and how to treat, remove and prevent them.

Mostly all pool-water contains metals. Some sources of dissolved metals are familiar; fill water, pool chemicals, deteriorating pool equipment, lawn fertilizers and other chemicals in rain runoff.

The increased use of stone, brick and marble around pools has added to the levels of dissolved metals in pool-water. This is because the acidic nature of rainwater, which typically has a PH of 5.0 to 5.6, but sometimes as low as 1.8 in highly populated areas. Acidic rainwater releases the metals found in these minerals of marble, flagstone ,etc. They naturally contain iron which can leach into a pool.

Balanced pool-water is essential. Poor chemistry in any pool, can eventually destroy pool equipment and surfaces(of gunite/concrete), and pull the plasticizer, (which gives liners their flexibility & elasticity), out of vinyl-liners.

PH is the most significant factor in preventing and removing stains, but it is often overlooked because pool-water can look clear, even with high PH or low PH levels.