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BEAT BLACK SPOT

10 May 2022

Black spot is tough to get rid of once established. Here’s how to treat and banish it for good.

Has the warmer weather enticed you out into the backyard to prepare for summer, only to find some nasty looking black spots in your pool? If so, it sounds like a case of 'black spot' algae infestation – the most stubborn type.

Here are some ways you can prevent black spot from invading your pool this summer, plus treatment options if it has already taken hold over the winter months.

What is black spot and what causes it?

The name black spot is given to this particular kind of algae because of the dark spot on top of the growth, which is usually the only visible part; if you only remove this spot, the algae will grow back within a few days. 

Black spot grows slowly but don't let this fool you, as it is very tough to get rid of once established. Algae growth is caused by an imbalance in the pH of the pool from wind and rain, so maintaining regular chemical treatments will help keep black spot at bay.

How do I prevent black spot?

Black spot can be hard to remove once it has attached itself to the walls of your pool or embedded in grout between tiles as it is chlorine resistant, so prevention is better than cure.

Keeping the right level of  free chlorine levels (above 1.5 parts per million) in your pool can help prevent the growth of black spot and other algae. After adding chlorine to pool water, make sure it is evenly distributed by keeping the water circulating properly. This is to ensure the chlorine reaches areas where black spot is most likely to grow, such as tight corners and the deeper end of the pool. Regular vacuuming and the removal of leaves will help prevent black spot also.

Disinfectant for your pool is also available to help prevent future outbreaks of black spot, but only apply this to the walls and floors of your pool when it is completely drained.

How do I treat black spot?

If you suspect you may have black spot forming in your pool, collect a water sample and bring it into your local Swimart or contact your local mobile technician. That way we can correctly identify what is affecting your pool and direct you towards the most effective treatment.

Obtaining the correct chemical regime for black spot algae is crucial, as other kinds of algaecide may not be as effective as those made especially for this type of growth.

Black spot still lurking around? Call Swimart on 1300 190 400 or contact your local technician for a home visit.

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