A pool/spa skimmer includes a housing, a face plate, and a flexible weir gate. The housing and plate are dimensioned to allow water to flow in a vertical column. The interior of the housing has a curved wall so that when a column of water passes through the open gate and into the housing, a whirlpool effect is realized. A vertical filter cartridge is mounted on a rotational bearing so that it can spin about its axis. The inlet of a pump is coupled to the cartridge via the bearing and is also coupled to a second water inlet via a vacuum operated valve. When the filter is clean, water is drawn through it and the filter spins about its axis due to the whirlpool effect. When the filter reaches a threshold dirt covering, water is no longer drawn through it and the vacuum operated valve.