The Forgotten Element?

It's Not Just Yellow Water That's a Problem: Understanding and Preventing Green Algae

Having a swimming pool at home is a real asset. After all, what could be better than going for a cooling swim on a hot day without even needing to go anywhere? Whether it's pool parties with friends, extending into the evening, or sunny weekends messing about with the kids, a swimming pool is sure to get a lot of use.

That is, until something happens to stop you from enjoying it. The green demon algae, a microscopic organism, can ruin your plans without warning when it suddenly decides to bloom in your pool, turning the beautiful clear water a nasty green that's sure to put anyone off dipping their toes in.

What causes this to happen? And, more importantly, how can you stop it?

The causes

Invisible algae spores are always in your pool water, mostly blown in on the wind. They're not a problem, for the most part, but all of a sudden, the conditions favour them and you have a big green bloom on your hands.

The conditions that lead to algae blooming usually need to work in combination. First, algae thrive on carbon dioxide, nitrates and phosphates, so these must be in fairly high concentration. Secondly, the water needs to be warm, with plenty of sunlight. Combine these factors with insufficient filtration and you might just find your pool turning green.

A dead giveaway that you might be in for an algae bloom shortly is the water suddenly turning cloudy. From then, it can transform in just a few hours.

The prevention

Since poor filtration can be a significant contributing factor to algae blooming, always make sure your system is working properly. Perform checks as regularly as you can and act on any blockages immediately.

Ordinary pool chemicals, such as chlorine, should be sufficient to kill algae and control the spores, so make sure you're adding them to the water in the recommended quantities, as regularly as you should. Missing just one dose could be all the algae needs to start taking over.

Some people recommend 'shocking' the pool water once a week. This just involves adding a dose of chlorine that's larger than normal in order to attack the algae spores and keep them under control.

It's also important to give the walls and floor of your pool a good brushing once a week. This will remove any spores clinging to the sides, putting them into the water where they can get picked up by your filter.

Talk with professional pool cleaners if you have any concerns.