The phrase "filter off" can be broken down into two parts: "filter" and "off." Antonyms for "filter" include add, scatter, mix, or pour. Antonyms for "off" include on, active, connected, or engaged. Therefore, antonyms for "filter off" might include adding, scattering, mixing, pouring, activating, connecting, engaging, or turning on. "Filter off" is often used in the context of removing or separating something, so the opposite could be combining or bringing things together. Using antonyms can help to convey a different meaning or tone in a sentence, and can provide more precise and descriptive language.