Pool Stains
Identify, treat, and prevent unsightly stains on pool surfaces
Stains on pool surfaces are unsightly and can be stubborn to remove — but with the right diagnosis, most stains can be eliminated. The key is identifying whether the stain is caused by metals (iron, copper, manganese) or organic matter (leaves, algae, berries).
Types of Pool Stains
Pool stains come in various colors, each indicating a different cause:
- Brown or rust-colored patches
- Green or blue-green stains
- Black spots on pool surfaces
- Rust-colored water or stains
- Purple discoloration on surfaces
What Causes Pool Stains?
Understanding the source helps choose the right treatment:
Metal Oxidation
Iron, copper, and manganese in the water oxidize when chlorine is added, depositing colored stains on surfaces.
Organic Debris
Leaves, berries, and other organic matter from surrounding vegetation stain pool surfaces over time.
Algae Staining
Dead algae leaves behind stubborn stains even after the active algae bloom has been treated.
Mineral Deposits
Dissolved minerals in the water deposit on surfaces, creating discoloration that is difficult to remove.
How to Remove Pool Stains (DIY Steps)
Follow this diagnosis-first approach to treat stains effectively:
- 1
Identify Stain Type
Place a vitamin C tablet on the stain. If it lightens, it's metal-based. If not, it's organic. This determines the treatment approach.
- 2
Vitamin C Test
Hold a vitamin C (ascorbic acid) tablet against the stain for 30 seconds. Metal stains will visibly lighten.
- 3
Apply Stain Remover
Use an ascorbic acid treatment for metal stains, or an enzyme-based cleaner for organic stains. Follow product dosing instructions.
- 4
Balance Water Chemistry
After stain removal, balance pH (7.2-7.4) and add a metal sequestrant to prevent restaining.
- 5
Brush Affected Area
Gently brush the stained area after treatment to help lift remaining discoloration from the surface.
- 6
Prevent Recurrence
Add a maintenance dose of sequestrant monthly. Keep vegetation trimmed away from the pool to reduce organic staining.
Professional Stain Removal
Some stains — particularly deep-set metal stains or large-area discoloration — require professional treatment. Our team uses specialized acid washing, chelating agents, and surface restoration techniques.
Staining in Portuguese Pools
Portuguese pools are particularly prone to organic staining from pine trees, olive trees, and bougainvillea — all common in pool-adjacent landscaping.
Frequently Asked Questions
How do I tell if a stain is metal or organic?
Place a vitamin C tablet on the stain for 30 seconds. If it lightens, the stain is metal-based. If not, it's organic. This simple test determines the correct treatment.
Can I prevent pool stains?
Yes. Use a metal sequestrant monthly, keep vegetation trimmed away from the pool, skim leaves daily, and maintain proper water chemistry.
Will acid washing remove all stains?
Acid washing removes most surface stains from concrete and plaster pools, but it removes a thin layer of the surface each time. It should only be done professionally.
Why does my pool get rust-colored stains?
Rust stains are caused by dissolved iron in the water — either from your water source, corroding metal fittings, or rebar exposed through worn plaster.
Are pool stains permanent?
Very few pool stains are truly permanent. Even stubborn stains from metals or algae can usually be removed with the right chemicals and techniques.
Need Professional Help?
Our expert technicians are ready to solve your pool problems quickly and effectively.