Filter maintenance is the most consistently underestimated task across every purifier in this family.
Follow the stated interval, not a guess
Xiaomi’s guidance for the Smart Air Purifier 4 Compact is 6 to 12 months depending on use, tracked by the unit’s own OLED display. Levoit gives similar guidance for the Core 300S. Set a reminder when the unit is new rather than waiting for a visible sign.
Pre-filters are often washable; HEPA media generally isn’t
Many purifiers separate a washable pre-filter, for larger debris like hair and dust, from the HEPA layer itself, which most manufacturers state should not be washed or vacuumed. Check your specific manual before cleaning anything beyond the pre-filter.
A visibly grey filter is already overdue
By the time a filter looks obviously dirty, it’s typically been reducing the unit’s effective CADR for a while — performance degrades gradually with no clear warning from most units.
Match a replacement to your exact model
Filters are cut to a specific housing. Check the compatible-model list published by the filter’s maker — whether the purifier’s own manufacturer or a third party — before ordering a replacement.
What we would not do
Suggest a single universal interval across every purifier in this family. Follow your specific model’s stated guidance and any on-device tracker rather than a generic “every six months” rule that may not match your unit or your usage.
The questions that keep coming up
Can I extend filter life by vacuuming it?
Only the washable pre-filter, on models that have one — vacuuming or rinsing the HEPA layer itself typically damages the fine filtration media rather than restoring it. Check your specific model's manual for which parts, if any, are meant to be cleaned.
Last reviewed 24 August 2026