Most, but unfortunately not all, staining on pool surfaces are preventable.  The problem is most people don’t realize they have metals in their water.  Even  trace amounts of these metals (iron, copper, manganese, cobalt, silver) can  cause staining.  In fact there’s enough copper in ONE penny to completely stain  an average sized swimming pool!  Obviously, the conditions have to be right.   This is where prevention & good, proper pool care come into play.

Here’s what happens:  metals come into your pool whenever fresh, make-up  water is added.  They’re dissolved in the water.  Whether it’s municipal water  or well water, metals can be present.  As the metals accumulate, the greater the  chance that they will eventually come out of solution.  Once out of solution,  they make the water cloudy or worse, they “plate out” on the pool’s surfaces & stain.  Metals can come out of solution through a variety of ways.  But  there’s 2 that typically happen.

When a pool is shocked whether with chlorine or a non-chlorine oxidizer, the  shock oxidizes everything in the water, including metals.  Oxidized metals  become “rust” in the case of iron or “Verdi gris” in the case of copper.

In the second way, metals come out of solution or are left “exposed” when the  pH, Total Alkalinity and/or Calcium Hardness are left unchecked & allowed to  go low (pH below 7.2, Total Alkalinity below 80 ppm [non-Pristine Blue pools],  Calcium Hardness below 100 ppm).  The water becomes aggressive & the metals  are more susceptible to oxidation.  In many cases, pool-owners don’t properly  test their water & more likely rely on the “look” of the water (the water’s  clear, everything must be alright).  This is typically the case with blonde hair  turning green – low pH helps bring copper out of solution & “plates” it out  on the person’s hair!  Then people blame the chlorine!  It’s the copper in the  water.

When it comes to testing, remember that you can only test for metals when  they are in solution.  Once oxidized, the metals come out of solution &  cannot be tested.  That’s why once a metal stain has occurred, the metal test  will NOT show any metals present.

Here’s how to prevent metal stains: Read More→