[dgacmu]

I ran a corsi-rosenthal box 24/7 for a year during covid with 4 merv-13 filters and the airflow stayed pretty good. Depends of course - we don't have pets and were running the HVAC filter full time also so it was a pretty clean environment. I would bet that the lack of a pre-filter would kill things fast if you had pet hair or lots of dust. But I suspect 6 months is totally reasonable from a "provides effective filtration" perspective.

Remember that as the filter starts to get dirty, its filtration effectiveness actually increases, though the airflow rate drops. CADR will drop but less than just watching airflow would predict.