Algae problems and a slippery pool liner can be caused by two factors:
Green, brown or yellow algae: Lacking sanitizer (chlorine)
Black algae: Lacking sanitizer (chlorine)
Green, brown or yellow algae: Adjust pH to 7.2 - 7.8. Add 350 g of Shock Treatment per 10,000 L of water. Pour 150 mL of 40% Destructive Algaecide per 10,000 L of water. Wait 3 hours then scrub the sides and the bottom. Wait another 12 hours then vacuum. Follow by a backwash.
Black algae: Same solution as for green, brown or yellow algae. However, scrub the sides more vigorously since black algae grow in layers. The longer they are there, the harder it will be to get rid of them.
Don't forget the sanitizer. For preventive measures, add 35 mL of 40% Destructive Algaecide per 10,000 L of water each week.
* In order to maintain clear and sparkling water during the swimming season, make sure to have your pool water analyzed regularly by your specialized retailer to adjust and maintain the following parameters: total alkalinity, calcium hardness and stabilizer. Ideally, the week following the opening of your pool, in early June and late July.