Many people first find out that they have metals in their water when unsightly stains appear. Metal stains most commonly appear shortly after the PH is raised or when you add chlorine. Organic stains can sometimes look similar to metal stains, but are typically left by algae or leaves that sit in the pool for a while, and leave a stain behind when cleaned up. Over the years we have even seen BB Pellets staining pools, bobby pins, nails, and other objects/toys containing metal parts.
Copper is in some algaecides, we suggest when purchasing your algaecide you are 100% certain it DOES NOT CONTAIN ANY COPPER! If the PH in the pool goes much below 7.0 for very long, copper can get into the water from a copper heat exchange coil, commonly found in pool heaters. Let’s also not forget to mention that in addition to staining the pool, copper can turn blonde hair green.
You can remove iron stains with Vitamin C, which is ascorbic acid. If you suspect a stain is caused by iron try the Vitamin C test. Simply place, or hold, a Vitamin C tablet against a stain for 30 seconds. If the stain vanishes, or lightens noticeably, in that area you should do an ascorbic acid treatment.
Keep in mind there is no practical way to remove metals from the water short of replacing the water. However, you should never drain your fiberglass swimming pool. You also need to find out how the metals got into the water so that this doesn’t happen again. If you have metals in the water you will need to use regular doses of a sequestrant to prevent the metals from forming stains. Sequestrants bind to the metals and prevent them from depositing as stains. Sequestrants slowly break down in the pool, so you need to add more regularly to maintain the correct level.
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, The Blue Stuff, and The Purple Stuff are some of the top sequestrants. You can also find many other brands with similar active ingredients, some of which are noticeably less expensive.