Algae stains

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How to remove Black Spot in swimming pools.

Signs of Black Spot staining

Individual black spots on pool surface

Spreading and multiplying over time

Raised black smooth lumps on surface

Shock chlorination only slightly improves

We do NOT recommend acid washing your pool to remove black spot algae.  This is because algae also lives in the pipework, filter and pump.  Once the pool is acid washed and refilled, the algae growing in your pool equipment will be reintroduced back into the pool and start spreading again.  We have removed black spot from dozens of pools that have already been acid washed just a few months earlier!

Algae is one of the most frequent issues pool owners face.  Thankfully, with our treatments, the problem can be fixed easily and quickly.  Algae growth can only occur in an environment where algae can survive. Obviously, the best way to eliminate algae is to remove the environmental factors that enable the algae to grow.  Once algae has been removed, then dealing with excess foliage and better chlorine management will help keep algae away in the longer term.

Our products will completely wipe out many forms of algae and bacteria that normal chlorine levels cannot. In most cases our quality algaecides will clear your green pool water within 48 hours.  These treatments will also completely remove black spot and mustard algae in around two weeks.

The trick to effective algae removal is using products that are strong enough to do the job.  Most algaecides that sell for less than $90 per bottle are diluted (watered down) and will not kill strong algae growths.  Cheap algaecides are cheap because you are paying for coloured water, not expensive active ingredients.  No product that we sell has water or colourings added to reduce its strength.

We are able to remove almost all algae types.  However, we strongly suggest that you act on black spot algae as soon as possible. If black spot stains are left for longer than 2-3 years the roots can sometimes be absorbed deep into the concrete pool interior and discolour it permanently.

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Causes of Black Spot stains in swimming pools.

Factors that encourage Black Spot

Foliage near pool with Black Spot

Constantly low chlorine levels

Constantly high pH

Lack of Shock Chlorination

Very high phosphates

Very old ‘rough’ pool interiors

There are two main factors that lead to algae growth – high phosphate levels and/or poor chlorination.  Phosphates are believed to be the main cause behind algae growth as they form part of the ‘food’ that algae need to survive.  Most pool experts agree that if phosphates are removed from the water, algae will struggle to survive.

On the other hand, it is not true to say that algae will grow if there are low phosphate levels present in the water.  Properly balanced, filtered and chlorinated water will not allow algae growth, even if low levels of phosphates are present in the water.  In short, it is not necessary to constantly add expensive products to remove small amounts of phosphates. Phosphate levels just need to be kept low with your water balanced and chlorinated properly.

Remove Black Spot without draining the pool.

Most Black Spot and mustard algae can be completely removed using our treatments on any pool finish including Pebblecrete, Quartzon, fibreglass, glass bead or fully tiled pools.  As the images show, we can remove Black Spot and other algae stains from swimming pool surfaces without draining the pool water.  Best of all, we can keep it gone.

If you are unsure of the type of stain you have please feel free to speak with us.

Copper stain reacting with chlorine

Please call us if you are unsure of the type of staining you have as the wrong treatment can make it much worse.  This image is of a pool that initially had mild metal staining.  Our customer believed that the metal stains were black spot algae.  He then treated it with granular chlorine to remove the stains and within an hour the pool surface was black. Treating a metal stain with chlorine and algaecides will oxidise them and turn them black.

OPTION 1 – Black Spot Stain Removal DIY Kit






  Simple step-by-step instructions included

   Phone support from our technicians

    Pool does NOT need to be drained

   Kit sent and tracked by Star Track Express

   Kids are back in the pool in 3 days

   Kit is $275 for pools 50,000+ Litres

OPTION 2 – Black Spot Stain Removal - Technician






  2 Litres of imported (2 step) high concentrate algaecide killing formula

    Pump, filter and chlorinator inspection

    High strength granular chlorine to shock the pool and catalyse the algaecides

   Pool does NOT need to be drained to remove the algae

   Kids are back in the pool in 3 days

   Visit is $395 for pools 50,000+ Litres

Removing copper from pool water.

CuLator Metal Eliminator removes copper and most other metals from pool water. This helps to prevent metal stains from appearing in your pool later. Algaecides may contain a copper complex that should be removed a few months after treatment. CuLator Metal Eliminator is unique because it can physically remove copper and other metals from pool water. Your pool shop will help you to measure the copper levels in your pool water. Click here for more information about CuLator Metal Eliminator.


Types of algae found in swimming pools.


  • This is the most common algae type found in swimming pools.  Green algae is one of the fastest growing algae types and will often turn your pool water green or cloudy overnight!   Green algae most commonly starts in corners or areas where automatic pool cleaners are unable to access.  Green algae can also occur in areas where circulation is poor or restricted (such as steps).  Low chlorine levels, warm temperatures and very high phosphates are the perfect combination for algae growth.  We can remove green algae in less than 48 hours and keep it gone.


  • ​This type of algae is usually easy to brush off the walls and floor of your pool, but it will often quickly return. It grows in shady areas of the pool which are protected from sunlight or areas of poor circulation. Just like black spot, yellow algae is somewhat resistant to normal chlorine levels.  Our treatment will remove mustard algae in less than 72 hours.


  • Black spot algae is unique in that it grows in the walls or floor of your pool, often in areas with low circulation and will not brush away like other algae. Black spot algae spreads slowly and is often mistaken for mold because it forms spots on the surface of your pool.  We suggest that you act on this type of algae quickly as its roots (algal spores) can penetrate into the pool cement and cause permanent damage and discolouration to your pool interior if it is not treated quickly. Black spot forms a protective surface layer that makes it resistant to chlorine.  Our quality process and products will remove black spot within a few weeks.  Some pool shops mistakenly believe that black spot can NEVER be completely removed.  It CAN be removed and we do it all the time! Pool shops will sometimes insist on acid washing for black spot because it is a great money spinner for their business. IMPORTANT NOTE: YOU DO NOT NEED TO DRAIN YOUR POOL TO REMOVE BLACK SPOT.
  • If you have black spots in a fibreglass pool please contact us for further information.


  • Unlike other forms of algae, pink slime is actually a bacteria, not an algae.  It often appears around skimmer boxes, lights, ladders and other areas of the pool. If not treated promptly, it will continue to slowly spread around the walls and floor of your pool.  We are able to remove pink slime algae for you.   It is not very common in Australia.