In this article we will help you determine if you have Organic Stains caused by leaves or debris or Inorganic Stains caused by iron or copper. Then we will help you remove the stains and prevent them in the future.
Organic stains are caused by leaves, algae or other organic matter sitting on the pool surface. To determine if you have an organic stain place a trichlor puck on the stain for a few minutes to see if it lightens or removes the stain. If it does then the stain is organic. To remove organic stains raise the FC up between 60% and 100% of shock level for your CYA, Pool School - Chlorine / CYA Chart, and brush often, daily if you can.
Many people find out that they have metal in their water when unsightly stains appear. These stains commonly appear shortly after the PH is raised; often when adding chlorine. Fiberglass pools and plastic components are particularly prone to iron and copper stains.
In the vast majority of pools metal staining comes from iron. Iron is fairly common in well water but rare in municipal water. If you suspect a stain is caused by iron try the Vitamin C test. Place 15 to 20 Vitamin C tablets in a sock and crush them. Hold the sock on the stain for 3 to 5 minutes. If the stain vanishes or lightens then it is iron.
You can remove iron stains with ascorbic acid (Vit C). See this article, Ascorbic Treatment to rid Pool of metal stains, for directions on how.
If iron has precipitated into the water, turning it orange, brown, yellow or green, it is sometimes possible to filter out the iron particulates using polyfill pillow stuffing material. Polyfill can be used by stuffing it in a skimmer basket or making a separate bucket filter filled with polyfill and circulating water through it, replace it often.
If your fill water has iron then consider trucking in iron-free water to fill the pool. Also consider capturing rain water or diverting gutters to the pool as an iron-free source of water for replacing evaporation and water loss.
Copper can also cause staining in pools. Copper is nearly always added to the pool by the owner. Common sources of copper are: mineral systems, ionizers, other "natural" sanitizers, pucks or shock labeled "blue" and algaecides containing copper. Another possible source of copper is low PH, below 7.2, eroding copper heaters or copper plumbing in older pools. A good sign of copper in the pool is blonde hair, fingernails, white dogs, etc turning green. Copper stains can be removed by putting dry acid in a sock and rubbing it on the stain. For widespread staining you can also try a no drain acid bath as shown here, The Zero Alkalinity Acid Treatment.
Generally, there is no practical way to remove iron or copper from the water short of replacing the water with new water that doesn't have any iron or copper in it. You can use a sequestrant to prevent metal stains. Sequestrants bind to the metal and prevent them from depositing as stains. Sequestrants slowly break down in the pool, so you will need to continually add more sequestrant on a regular basis to maintain sufficient level to keep the iron or copper sequestered.
Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are the most effective. ProTeam's Metal Magic and Jack's Magic The Pink Stuff (regular), The Blue Stuff (fresh plaster), and The Purple Stuff (salt) are some of the top brand sequestrants. There are also other brands with similar active ingredients, some of which are noticeably less expensive.
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