The problem with stains can happen in masonry pools (insert, tile, porcelain tile) and also in vinyl pools. 

It is interesting, first of all, check the type of stain that comes in your pool. Should identify what kind of stain is it in the pool vinyl pools, there is a certain manufacturing defects that encourages the growth of a species of fungus that eventually stain the walls and the bottom of the pool.

The vinyl pool usually has several years of warranty against manufacturing defects and these spots caused by fungi, are considered a manufacturing defect.

 There are several factors that can cause stains in the pool:

– Development of algae

– Metals used in water supplies

– Cracks allowing penetration of dirt and organic matter at the base of the coating

How to remove a stain from your swimming pool? 

Leave a trichlor tablet in contact with the stained surface;

Leave the tablet until the stain is gone completely, remembering to scrub daily local stained 

During this period the pool should not be used if the chlorine content exceeding 3 ppm , and to use it, the tablets should be removed and stored in a plastic bucket with pool water.

Stains on fiber and vinyl pool 

Stains on vinyl pools or fiber can be removed by lowering the pH to below pH 6.8 using reducer. Lowering the pH becomes acidic water and softens stains making them easy to remove. 

The treatment may have the duration of one week, during this period the pool will be closed, and brushing of spots on the surface of the pool should be performed with a brush. Do not use abrasive materials. 

After removing stain, vacuum the bottom of the pool with the filter in the drain position. Adjust the parameters of alkalinity and pH, keep the chlorine content of between 1 and 3 ppm.