so I have heard that you should set it to have your phosban tumble slightly. What is the reason for this. RIght now I have my reactor almost filled up with carbon first and phosban after and there is not any tumbling. I can set my powerhead higher, but I am just wondering why it makes a difference? I would think that tumbling would give water a better chance of dodging thru the granules and escaping without being "cleaned" rather than it having to squeeze thru a thick layer.