Pool Stains 101: What’s Causing That Discoloration and How to Fix It
No one wants to walk out to their pool and see brown splotches on the steps or a mysterious purple tint creeping along the waterline. If your pool has strange discoloration, don’t panic, it’s more common than you think, and in most cases, it’s completely treatable. At Maritime Pools, we’ve seen just about every kind of pool stain imaginable. Here’s a breakdown of the most common types of pool stains, how to identify them, and what you can do to get your pool surface looking like new again.
Metal Stains (Usually Reddish-Brown, Rusty, or Green)
Common Sources:
– Well water with high iron or copper
– Pool heaters (copper components)
– Old metal objects left in the pool
How to Tell:
– The stain doesn’t brush off.
– Color may change with a vitamin C tablet test (lightens = metal).
How to Fix It:
– Use a metal sequestrant to keep metals in solution.
– Stain removers with ascorbic acid (vitamin C) often work well.
– Avoid adding shock or chlorine until the stain is fully treated.
– Long-term: Consider adding a filter pre-treatment if you use well water.
Organic Stains (Typically Brown, Green, or Blue-Green)
Common Sources:
– Leaves
– Algae blooms
– Acorns or berries falling in the pool
How to Tell:
– Usually appear on steps or corners where debris collects
– May brush off partially
– Can smell a little funky if fresh
How to Fix It:
– Brush the area and shock the pool.
– Use an enzyme cleaner if debris or scum line buildup is present.
– Prevention: Skim daily, trim trees, and maintain proper chlorine levels.
Scale or Mineral Deposits (White, Grey, or Light Brown Buildup)
Common Sources:
– High calcium hardness
– Imbalanced pH or alkalinity
– Evaporation, especially in sunny climates
How to Tell:
– Feels rough or crusty to the touch
– Forms along the waterline or tile
– Doesn’t react to stain removers
How to Fix It:
– Acid wash for extreme buildup
– Gentle scrubbing with a pumice stone or descaler product
– Maintain balanced water chemistry to prevent recurrence