From Bulbapedia, the community-driven Pokémon encyclopedia.
The Purification Chamber is a series of nine sub-chambers located in the Pokémon HQ Lab, developed by Michael's father and Professor Krane to make purification faster just in case Cipher would ever return.
A sub-chamber operates via the elemental types of the Pokémon in it. That is, the effectiveness of the purification sub-chamber depends on what the types that the Pokémon inside do to the other Pokémon inside. Whether the type has no effect (Ground on Flying), a weak effect (Fire on itself), a normal effect (Normal on Grass), or a strong effect (Dark on Psychic) determines whether the flow is very weak, weak, normal, or strong, respectively. The effectiveness can be against either type, and stem from either type. For the purposes of the Purification Chamber, it is assumed that Normal is strong against itself.
A sample setup of a sub-chamber that has strong flow all around would be as follows: