There are two issues. Sanitizing is just maintaining the chlorine level. The other issue is actually taking that water through the filter "X" times a day. The chlorine will kill the microbes but you still need to get their dead bodies out of the water or they decompose and you get algae growing. It also makes the water cloudy. Commercial pools also have a turbidity standard. You pretty much have to be able to make out the slots in the screws holding the main drain cover on from the deck.
