WHAT CAUSES THEM? 

STAINING

Metal discolouration and staining in pool water is essentially a chemical reaction similar to rusting, but it happens directly in the water. When metals—like copper, iron, or manganese—are present in the water, they remain invisible and dissolved until a “trigger” causes them to solidify and fall out of solution.

Pool owners commonly mistake stains or water discolouration for pool algae. However, unlike algae, pool stains do not brush off readily and are not slick or slimy.

The Two Main Stages

• Discoloration
  When you add a high dose of chlorine or if the pH levels spike, the dissolved metals “oxidise” (like an instant rust). This causes the water to change colour while remaining clear—common examples include translucent green (copper) or reddish-brown (iron).
• Staining
  If the oxidised metal particles aren’t treated, they eventually settle onto the pool’s floor and walls. Once they land on a porous surface like plaster or marbelite, they “plate” onto the finish, creating a permanent-looking stain.

Common Triggers

• High pH or Alkalinity: High levels make the water “scale-forming,” which forces metals out of the water and onto the surfaces.
• Heavy Shocking: A sudden surge of chlorine can rapidly oxidise any metals currently hiding in the water.
• Source Water: Using borehole water or certain municipal supplies that are naturally high in mineral content.
• Equipment Erosion: If pool water becomes too acidic (low pH), it can slowly eat away at copper heater coils or internal components, adding metal into the system.

SCALING

When your pool water becomes oversaturated with calcium (usually due to high pH, high total alkalinity or high calcium hardness levels), the calcium has nowhere to go. It “drops out” of the water and crystallises on your pool surfaces. Think of it like the limescale in your kettle.

HOW TO TREAT STAINING & SCALING

PoolBrite Metal Magic is a “sequestering agent.” It essentially grabs onto the dissolved metals and minerals in the water, keeping them in a liquid state so they can’t settle on the walls or, in some cases, helping to lift fresh stains back into the water.

How to Apply:

• Balance First: Ensure your pH is between 2 and 7.6. If your pH is too high, the Metal Magic won’t be as effective.
• Clean the Filter: Backwash and rinse your filter thoroughly before starting.
• Apply Metal Magic: For a standard treatment, use approximately 250ml per 10,000 L of water.
• Circulate: Pour the product directly into the water around the perimeter of the pool. Run your pump on “Filter” for at least 24 hours to ensure the product is fully distributed.
• Brushing: For scaling or fresh stains, give the affected areas a vigorous brush after adding the product to help “lift” the deposits.
• Note: If the scaling is very old and “calcified,” you might need repeated treatments to soften the scale. Metal Magic is best for metal stains and preventing new scale.

HOW TO PREVENT STAINING & SCALING

• Test Your Source Water: If you fill your pool with borehole water, it’s likely high in metals. Add a maintenance dose of Metal Magic 25ml per 10,000L weekly.
• Keep pH in Check: Scaling almost always happens when pH stays above 7.8 for too long. Aim for 4 – 7.6.
• Watch Your Calcium Hardness: Keep it between 200–400 ppm. If it gets too high, the only real fix is to partially drain and refill with fresh (low-calcium) water.
• Avoid “Metal-Heavy” Chemicals: Use high-quality algaecides that use protected copper (Month Mate All-In-One Algaecide or Tru Blu) or are “non-metallic” or “copper-free” (PoolBrite Green Go) to prevent accidental staining.