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London Swimming Pool Company
Unit 1, Shannon Commercial Centre
Beverley Way, New Malden, KT3 4PT
Tel 020 8605 1255

Registered in England No: 07274168
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Blog

15 July 2019
How to Combat Algae in Swimming Pools

Owning a pool comes with a certain level of responsibility, particularly when it comes to maintenance and the health of the pool water.  A poorly maintained pool will quickly become unusable and the longer the neglect continues, the longer it will take to rectify problems. This is the case with algae, a naturally occurring problem for pools if proper attention is not given to maintaining good circulation, filtration and sanitisation. We look at how to keep algae at bay.

Different Types of Algae
There are three types of algae that typically present in swimming pools: green, black and mustard. Each present in a different way. If you have a green algae problem, the water will probably be green and murky, and you'll have growth on some or all surfaces. It will be slippery and unpleasant to stand on or touch. If the pool has black algae, there will be rough spots of it on the bottom of your pool.

Mustard algae (also referred to as yellow algae) is not slippery, looks like sand, dirt or a stain in the pool. It is less common than green and black algae and is very persistent and can attach itself inside the pool, on the filter, pool equipment and even items in the pool, such as toys and inflatables. 

Although algae growth is unsightly, it is not dangerous in itself; it will not harm the swimmer. However, the issue is that algae provides a breeding ground for bacteria which can be harmful to bathers’ health. Bacteria multiplies in the heated environment of a swimming pool, and coming in contact with these bacteria could lead to various illnesses including gastrointestinal and respiratory problems.  So, you can see that it’s imperative to keep algae at bay for health reasons and, of course, to keep your pool looking as splendid and inviting as the day it was built.

How to Defeat Algae
Although there are different types of algae, growth is caused by the same kinds of things. This might include poor circulation, possibly as a result of a broken or elderly filter. It may also be down improper water balance (needing a chemical boost, be it chlorine or a pH adjustment) or poor and/or irregular maintenance.

Algae can be eradicated by following a few simple steps. Begin by checking the filters. You can either clean the filter by backwashing it, or replace it with a newer, better model. This is done to correct any circulation problems that may exist; you should also check the plant for the same reason.

Following this, you shock the pool by adding a large dose of chlorine.  However, this will only be enough in the case of green algae. For black and mustard algae, you will  need an even larger dose – perhaps two or three times the amount of chlorine.  As mentioned earlier, mustard algae is very persistent and black algae can actually root itself in concrete, making it harder to kill. You can also use a specialist algaecide to tackle the problem. NoPhos, one of the products we use for our clients’ pools, is a natural product that eliminates phosphates from entering pool water, thus preventing algae and bacteria growth in the first place. 

Use a brush to remove all visible growth on the walls and floor of the pool. Pay attention to the difficult-to-reach areas, for example, behind pool ladders or in tight corners. If you don't  remove the growth, the algae growth is highly likely to become a problem again in the future.

Be sure to clean all items that have resided in the pool and been exposed to the algae, for example, inflatables, poles, pool cover.

Following up Maintenance
It's imperative that you keep a close eye on your pool over the days following a shock and cleaning. Test the water to ensure the correct pH levels and correct them if necessary. If you used your pool filters to remove the dead algae from the pool, check and clean the filters again.

At London Swimming Pool Company we specialise in swimming pool maintenance, servicing and refurbishment in Surrey, so if you have a pool that’s in need of regular maintenance or a facelift, contact us for an initial discussion – there’s no substitute for expert advice. If you have an older swimming pool that needs upgrading, we suggest planning your refurbishment for the autumn, so all the work is done and dusted before the next swimming season.

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