I think he means vodka dosing, biopellets, or other means of adding a carbon source to help elevate bacteria levels.

There are things to consider with your ph before making adjustments. First i would see what my ph is doing through the day. Start recording your ph before the lights come on (this should be the lowest your ph will get) and again right before your whites turn off for the day(this should be your highest). If the difference between the 2 numbers is below .2-.3 then you're fine. If there's a larger difference then it'll take more looking into. It's better to try to pinpoint the cause first rather then just using additives right off.

Do you run a fuge? If so, put the fuge on an opposite light cycle to the main tank. Is your flow breaking the water surface some for gas exchange? Is your tank in an open area of the home? Depleted oxygen levels in will also cause ph to drop. Opening a window helps.