What does co-current regeneration mean in practice?
The regenerant front moves from top to bottom and final quality depends on dose, distribution and complete rinsing.
When does it matter?
It is mechanically simple but may use more regenerant than a well-designed counter-current system for the same endpoint.
Which solutions are related to it?
Set it for resin type and volume, injector and hydraulics and assess residual hardness and salt consumption.