Algae are a major problem for outdoor pools. The only effective way to remove algae is by shocking the pool (see shock treatment section) so you are advised to prevent algae from occurring in the first place. This can be achieved by using an algaecide. Polyquat algaecide is absorbed by organic debris such as leaves and dead algae so it is important to clean the pool thoroughly with a brush or vacuum cleaner before starting the chemical treatment.

At the start of each season it is recommended to dose 1 litre of algaecide to each 10,000 gallons of pool water. This will help prevent algae getting established in your pool.
Each week add 250 millilitres to each 10,000 gallons of pool water to continue the protection against algae.

As well as using algaecide there are also a few other things you can do to help prevent algae getting established:

1. Brush regularly, especially walls and deep end, to prevent invisible algae colonies from forming.
2. Test your pool's sanitizer levels regularly and never, NEVER let sanitizer levels get low.
3. Make sure your filter is working properly, and that your pump runs at least 6 hours per day, preferably divided into two different intervals.

Multifunctional tablets already contain algaecide so if you choose to use these then you should only dose your pool with 1 litre of algaecide to each 10,000 gallons of pool water at the start of each season. After that initial dose, the multifunctional tablets will supply sufficient algaecide to help prevent algae getting established.