I have no answer to this question. All I want to say is that you can find charcoal refill online, for charcoal filters.😊
Just so you check if this option is available for you before buying a new complet filter :)
I used Carbon filter on the end of my previous grow. Because the smell went out the house for the first time lol.
I'm going to use it from start to the end with my current grow. I had no real proof it was working since I've placed it verry late,
smell was already everywhere tbh. The REAL test for me will be my neighbor nose this time 😄 If I don't ear from him, will mean it worked :D