If possible could you be a bit more specific. If i am flooding twice in 1 hour can you give me a rough idea how long the flooding should take? 10min, 20min? It seems that the flooding process is more of a flushing minerals through the bed rather than an actual flood ! am right in thinking the bed never actually fills to its capicity during the process as it should be draining at the same time?
Are the flood and drain pipework diameter the same to ensure the flow and return run at the same speeds?

Thanks in advance