Phosban Reactor and Media Tumbling

[LBCBJ]

I just added a Phosban Reactor to my 18g SPS tank, and such a small water volume I'm only using about 30g of Phosban media. The problem is with getting the media to tumble correctly. I'm using a Mini-Jet 400 and have it on the lowest setting, which is about 20 gph, but this causes no media tumbling at all. But when I ramp up the flow just 10-20 gph more, it throws all of the media into suspension, making a mess. So my question is, does the media actually need to tumble, or will not tumbling cause clumping issues?

[BLockamon]

Tumbling uses the media more efficiently but is not required. I personally don't like the media to tumble because it restricts me to too low of a flow. I pack the chamber with Phosban and carbon so that I can flow faster.