Aquaman#10(1963)

The evil water sprite known as Quirk invents a device which can steal power from other water sprite's. He turns the weapon against his own brother, Quisp, and removes all of his magic. Quisp swims away to seek the aid of his old friend, Aquaman. Aquaman and Aqualad return with him to Quisp's kingdom. Quirk's gang attacks Aquaman and succeeds in capturing him. They then imbibe a special form of seaweed that transforms them into giants. More powerful than ever, Quirk and his cohorts prepare to invade the surface world. Before long, Aqualad manages to escape from his prison and frees Aquaman. Aquaman catches up with Quirk's gang and recoves the item responsible for stealing Quisp's powers. He attempts to use it on him again in the hopes of restoring the sprite's magic, but it renders him unconscious instead. Aquaman and Aqualad consume the same magic seaweed to transform themselves into giants in order to fight Quirk. Quisp eventually recovers and helps them to end Quirk's threat once and for all. The growth formula effect eventually wears off, and Aquaman and Aqulad return to normal size. Quisp regains his magic powers.