I'll get some details wrong, but here's what I remember from a recent conversation.
Like everything else in life, cleaning a pool is surprisingly deep the more you look into it. Factors that matter:
- the size and shape of the pool (obviously)
- whether the pool is above or below ground
- what material and tensile strength the pool cover supports
- the choice of motor to pull the cover
- whether the pool cleaner is above or below the water level of the pool
- whether the pool is exposed to much light, and how this affects the chemical efficacy of chlorine, and whether the chlorine needs to be correspondingly buffered
- whether the pool is heated by gas, by solar, or with a heat pump
There's even an entire podcast dedicated to it, and I'm sure there are others.