Whether switching the direction of flows in activated carbon beds impact the absorbtion capability.?

the carbon bed used to run with flow from top to bottom. Inorder to see whether i can achieve a long carbonbed life, i reversed the flow. The results were encouraging until such a time where I had to reverse the flow back ( from top to bottom) due to some upsets in the process. The bed suddenly look depleted. Do anybody have any similar kind of experience and if so what was done to correct it.