Stains are primarily caused by the introduction of metals into the water which reacts with coloured metal oxides. While stains will vary in size from small ones to larger ones, there are extreme cases where the whole pool surface is stained. Pool stains are treatable and to do so, it is best to determine what type of stain it may be.
Most commonly leaf or berry stains, where a leaf has been allowed to sit in one place for weeks and its tannins and oils stain the area. Algae stains occur if/when the pool stayed green for a period of time. Dirt also gives rise to organic stains. Dirt can be washed in the pool after a storm (or if the hydrostatic valve operates and dirty water enters the pool, characterised by a discoloured ring around the main drain). These are most commonly yellow, green and brown in colour.
Metal stains can occur for a number of reasons. One of the most common occurs when you have unknowingly left a metal item in the pool and it has rusted. The most common metal stain is from Iron which gives a yellow through to brown discolouration. You can also get Black Spots in Fibreglass pools which are Cobalt stains.
Salt stains are an increasingly common form of stain which can be caused by using cheap, low quality salts. Talk to us if you start noticing these and we will recommend quality salt products for your pool. Often it is the iron in the salt which depending on the severity gives green through yellow to brown stains. Alternatively, some magnesium salts (aka Manganese) can stain pools which gives dark brown to black stains.
The scale is usually coloured because of the inclusion of metals and dirt. In the strict sense, the scale is not a stain but a deposit of Calcium Carbonate (chalk) on the pool surface which can be
recognized by its milky appearance and rough surface (often referred to as similar to ‘sandpaper’). These stains are directly related to the pools calcium and pH levels. Test your pool water balance instore for free whenever we are open to avoid these buildups.
All of these pool stains are treatable and many treatments can be done without having to drain your pool.