Experiencing An Algae Bloom? Here’s How To Clean Your Pool


Pool algae can be caused by chlorine levels that are too low, imbalanced water chemistry, as well as bad filtration. Algae can also end up getting introduced to your pool water through swimwear or toys that were exposed to a natural body of water. Should you notice algae developing, especially in the earlier stages, then it’s time to act. If you leave the algae in your pool without getting rid of it, then it could multiply in a rapid manner. If this happens, you could have algae bloom on your hands.

If your fibreglass pool does have algae, then a normal dose of chlorine will not be enough to kill it. Neither can your pool filter effectively get rid of algae spores. Should you want to get rid of the algae in your pool, then you’ll need to deep clean it. After cleaning your pool, you should try to avoid algae blooms from developing in the future.

Pool Algae: What Causes It?

Algae spores can be found anywhere. They can enter your fibreglass pool through dirt, rain, and even the wind. These algae spores tend to become a problem when they start multiplying in the pool water. You don’t want to deal with an algae bloom or have algae growing on the walls of your pools. Your local Brisbane fibreglass pool team are more than happy to advise you on the best way to maintain your pool.

There are several things that can contribute to an environment that’s perfect for the growth of algae. Your pool’s chlorine levels could be low, the pH levels could be improper, your filters could be dirty, and more.

Preventing the growth of algae is easier than getting rid of an active algae infestation. This is why it’s important that pool owners keep their pool water balanced and their filtration system clean. Should any swimwear or toys have been used in natural bodies of water, then these should be thoroughly cleaned before being introduced to the pool water.

Different Kinds Of Pool Algae

When you know what kind of pool algae you are dealing with, you can come up with an effective treatment plan. There are three kinds of pool algae:

  • Green Algae: These are the most common as well as the easiest to kill. Green algae have a tendency of spreading quickly and can cloud up the pool water. You could see green slime on top of your fibreglass pool.
  • Yellow Algae: Also known as mustard or brown algae, this kind of algae is usually found in humid conditions. This kind of algae is resistant to chlorine and can resemble pollen or sand globs found clinging to shady areas of the pool.
  • Black Algae: This is actually a bacteria. The roots will end up digging into the concrete surfaces. This kind of algae is very hard to kill. You’ll need to go through multiple rounds of deep cleaning to get rid of black algae, and they also regrow really fast if you aren’t quick enough to clean it out.

How Can You Get Rid Of The Algae In Your Pool?

To get rid of algae, you’ll need to rapidly vacuum as well as brush your fibreglass pool. The water chemistry of your pool should also be balanced, and then you’ll need to shock and filter the pool water as well. This is what you should do:

1) Manually Vacuuming The Pool

If you have a robotic or automatic pool cleaner, then note that they can’t effectively get rid of pool algae. What you’ll need to do is manually vacuum the pool using the ‘Waste’ setting on your pool filter. This way you can bypass the pool filter, ensuring that the algae-filled water doesn’t re-enter the pool.

You should also ensure that you refill the water in your pool as you vacuum it. The water level should be maintained up to halfway up the pool skimmer.

2) Brushing Pool Walls And Floor

With the help of a stiff pool brush tied to a pole, thoroughly brush both the walls and the floor of your fibreglass pool. Pay attention to areas where algae deposits can be at their worst, such as corners and crevices. As you keep brushing your pool, the pool water will turn cloudy. This can obstruct your view, so ensure you clean the tougher areas first.

3) Testing And Balancing The Pool Water

You can make use of test strips, a liquid test kit or a digital test kit to test the alkalinity and pH of your pool. When the pH is high or the alkalinity is low, this can inhibit pool shock.

4) Shocking Your Pool

Adding shock to the pool essentially super-chlorinates the pool water. This is an extra dose of sanitiser that can kill the growth of algae. Depending on the kind of algae you have in your pool, you’ll need different amounts of shock.

  • For green algae, you need double the dose of shock
  • For yellow or dark-green algae, you’ll need three times the amount of shock
  • For black algae, you’ll need four times the amount of shock

You should shock your pool when it’s dusk or when it’s nighttime out. This is as sunlight can eat up the chlorine, should you shock the pool when the Sun is out. Also, in order to ensure that your shock is circulated, you’ll need to run your pool filter for at least eight hours or overnight.

5) Filtering The Pool Algae Out

The shock treatment will end up killing all the algae in the pool. When this happens, the pool water will turn into a cloudy blue colour. You’ll need to run the filter continuously for at least eight hours in order to filter the algae particles out.

6) Testing Pool Water Once More

The chemical levels in your pool water need to be balanced and the chlorine level back to normal before anyone can use your pool. Test the pool water, and adjust the pH, the alkalinity and the chlorine levels as required. You should also check the cyanuric acid as well as the calcium hardness of your pool water. This is because, by this point, the water in your pool will have been replaced with fresh water.

7) Cleaning The Pool Filter

Your filter has already processed large amounts of water that was contaminated. To prevent your filter from releasing algae spores back into your pool water, you’ll need to clean the filter. Your filter cartridges should be soaked in muriatic acid that has been diluted. You could also consider replacing them. Should you have a sand or a D.E. filter, then you’ll need to backwash it.


If your fibreglass pool is full of algae, then you’ll need to thoroughly clean it before you can go back to using your pool. Depending on the kind of algae you have in your pool, you’ll need to add different amounts of shock. This guide can help you learn how to get rid of algae from your fibreglass pool.

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