At a conventional activated sludge plant, the operator observes clumps of sludge floating on the surface of the secondary clarifier. The final effluent is still meeting typical performance expectations with good BOD/TSS removal, and the clarifier looks clear except for these floating sludge patches. The sludge blanket is deeper than normal. When a sludge blanket sample is gently placed in a clear container, small gas bubbles form and lift bits of floc (a “boiling” appearance), indicating denitrification and dissolved nitrogen gas in the blanket. Which operational response is the best immediate corrective action to stop the clumps of sludge from floating in the secondary clarifier?