How to Identify Pool Stains
How we identify pool stains
8 out of 10 customers in 2025 tried at least one retail stain product without success before removing their stains with our treatment.
Wrong treatments make stains worse
The wrong pool stain remover can actually make your stains worse? This is because the organic acids in cheap stain removers chemically ‘fuse’ the stain to the pool surface. This reaction ‘bakes’ the stain onto the pool surface, making stain removal much harder. Some of the hardest jobs we have ever done have been where the client has tried multiple stains removers before calling us.
Many customers search for the ‘best’ pool stain remover, unaware that there is no single solution that fixes every stain type. Matching the stain treatment with the type of stain in your pool is what we do every day.
With over a decade of experience and 20,000 pools transformed, we diagnose and treat pool stains nearly a dozen times each day. Our products save you time and money by getting it right the first time.
Feel free to contact us for a no-obligation consultation about your pool stains.
The 5 most common pool stains
Here are the 5 most common stains that we see across Australia in swimming pools.
- Black Spot Algae. Black Spot Algae is always raised, round, lumps on the surface of the pool that look like mold. It is never blotchy or smears, it is always defined black lumps
- Rust Stains. Rust usually comes from metal objects that have fallen into the pool and left a rust stain on the surface. Sometimes rust comes from the steel in the pool structure but this is far less common.
- Copper Stains. Copper stains are tricky because they can be blue/green, brown or black depending on the water chemistry. Copper comes from algaecides, chorine free sanitisers and some clarifier blocks.
- Calcium Stains. Calcium hydroxide generally forms in lumps (nodules) that seem to ‘weep’ down the pool surface. Calcium carbonate will generally form as a thin ‘scale’ across sections of the pool.
- Brown Stains. Brown staining is usually from either leaves, contaminated pool salt, copper, body oils/sunscreen, minerals, or dirt.
Most common pool stain mistakes
Several times a week we have clients who are convinced that they have a certain stain type. After speaking with us and using our treatments they are surprised that it was a different stain. Here are some common mistakes.
❌ Oxidized copper mistaken for algae
❌ Calcium carbonate mistaken for bleaching/fading
❌ Iron mistaken for yellow/mustard algae
❌ Black algae mistaken for copper stains
❌ Calcium nodules mistaken for calcium scale
Proven treatments for all types of stains
Pool stain removal is all we do! Click on any of the stain types below for more information.
Calcium Deposits
Calcium is the hardest type of issue we treat each day because it forms in a pool for a variety of reasons.
Rust Stains
Most rust stains in swimming pools come from metal objects that have fallen into the pool such as metal…
Copper Stains
Copper stains in swimming pools can appear in a variety of colors and its very challenging
Black Spot Algae
Don’t drain your pool to fix black spot algae because it will just come back again. We fix it.
Calcium Fibreglass
Our calcium remover kit completely clears the hard white calcium buildup on fibreglass pool surfaces.
Calcium on Tiles
Typically forms and becomes visible on swimming pool tiles at some stage in the life of almost every pool.
Salt Stains
In recent years, there has been a significant increase in brown stain in salt water pool surfaces.
Brown Stains
The best way to remove brown stains in swimming pools is by using our brown stain treatment kit.
Algae Staining
This is green / brown in colour and doesn’t respond to chlorine, scrubbing, or algaecides.
Not sure what’s causing your stains or what stain you have? Send us a few photos and we’ll take a look — no obligation, no purchase needed.
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