pH- Bloom : pH ReducerpH Regulator Reducing pH for Max Yield! pH is designed specifically to reduce the pH level during the Bloom phase. pH Bloom uses Phosphoric Acid as its main ingredient. Usage Use pH Bloom to balance your pH after adding the nutrients only in BLOOM Keep your pH between 5. 8 6. 5 to make sure all the elements get taken up by the roots You only need a couple drops per gallon to lower your pH to the desired levels How does pH Bloom work?