The easiest way to clean dirt from the bottom of a pool is to vacuum it with a vacuum. If there is a lot of dirt, it is best to do it with the multiport valve for debris; otherwise, it can be done in the filter configuration and then washed against the current to expel the dirt. While it may seem surprising if you're new to pool care, you need to scrub the walls inside the pool with a stiff brush even when there's water in the pool. This loosens the debris that adheres to the walls, allowing it to descend to the bottom of the pool, where it can be removed.
Brush walls every week during the bathing season while the pump is turned off. A vacuum cleaner removes debris that accumulates on the bottom. To vacuum it is necessary to move the vacuum head over the debris at the bottom of the pool until the bottom appears clean. For example, removing large chunks of debris requires a different method than removing algae, sand, or oil.
Some are like automatic vacuums that remove waste and deposit it on the pool filter; others are autonomous and filter fresh water back to the pool.