how bad is it to take the exhausted air and put it back in tent?

and can i put 2 filters the same cfm before fan or just one before and 1 after?
jaymu104 Reviewed by jaymu104 on . exhausting a 5x5 tent how bad is it to take the exhausted air and put it back in tent? and can i put 2 filters the same cfm before fan or just one before and 1 after? Rating: 5