A nano-bubble generator includes: (i) a housing defining: an inlet for receiving a liquid with entrained macro-bubbles: a first chamber operatively downstream of the inlet; a second chamber operatively downstream of the first chamber; and an outlet operatively downstream of the second chamber; (ii) at least one blade disposed within the first chamber for, in use, cutting macro-bubbles entrained in the liquid to convert such macro-bubbles into micro-bubbles; (iii) at least one first magnet within the second chamber; and (iv) at least one second magnet associated with the second chamber, wherein: (a) the at least one first magnet and the at least one second magnet are arranged such that the polarity of the at least one first magnet is opposed to the polarity of the at least one second magnet; and (b) the at least one first magnet is movable relative to the at least one second magnet.