Covering the pool is a great way to prevent algae growth. The right cover can stop algae from entering the pool, as well as leaves, insects, bacteria and dirt from decomposing in the pool, which provides food for the algae. Algae blooms occur when there is enough food for them to eat. To prevent this problem, we recommend using a retractable pool cover.
This will stop dirt, dead insects, twigs and even bird droppings from contaminating the water. A pure black pool cover or tarpaulin will block out sunlight and deprive algae of the light they need to survive, killing them. However, pure black tarpaulins or pool covers have a major drawback. They act like giant solar panels and trap energy from solar heat, turning the cool pool water into a warm bath.
If water starts to accumulate on your deck, you can use a deck pump and a bucket net to drain it. You should also open the cover to allow the pool to be brushed and check the pH levels, lowering them if they are 7.8 or higher. Keeping the cover clean during the time the pool is closed or not in use will make it easier to open it again next season. To avoid algae in the pool, use a reflective cover on its top side that prevents heat absorption and keeps water cool for swimming.
If you already have a low amount of chlorine and phosphates in your pool, adding a solar pool cover (which heats the water) will help existing algae thrive. Take a water sample to the pool store and they'll determine what you need based on your pool's water status. In order to keep your pool free of algae during the colder seasons, make sure to keep it almost full during winter to prevent damage from hydrostatic pressure. Removing black algae can be a long and difficult process and sometimes it will require you to drain the pool and acid wash it.
Additionally, make sure to keep your cover clean and open it occasionally to brush your pool and check pH levels.