Great Britain collected 28 medals at the Barcelona leg of the Mare Nostrum series, including nine golds.
Swansea's Jazz Carlin set two championship records as she won gold medals in the 1500m and 400m freestyle.
Adam Peaty, from City of Derby, set a new British record of 59.25 seconds with victory in the 100m breaststroke.
Commonwealth Games champion Fran Halsall (Loughborough) swam one of her fastest times of the season to win the 50m freestyle in 24.40.
James Guy (Millfield) took gold in the 400m freestyle while Ben Proud (Plymouth Leander) won the 50m butterfly.
Hannah Miley (Garioch) edged out team-mate Aimee Willmott (Middlesbrough) in the 400m individual medley, Siobhan-Marie O'Connor (Bath) won the 200m individual medley and Georgia Davies (Loughborough) collected gold in the 50m backstroke.