Point taken, but the comment re fouling is still relevant. Resin on the move will flow around headers and laterals if it is in its normal condition, however if it is fouled it can move as one lump, ask any resin manufacturer. This can happen to any resin bed packed or not. I have seen a mixed...
I hate to disagree with the previous answers. However if the unit was a packed bed then piston action is unlikely, the bed is packed! I would get a sample of the resin and have it tested, if the there is any foulant that alows the resin to stick together then you might see a piston effect during...
