I use the PhosBan reactor by two little fishys. Essential the same thing as yours.
I run it with a small powerhead and a valve on it to regulate flow.
You are correct, they have to be really fine tuned. Too much flow and you blow the beads into the sump/tank and its a mess. Too little and you don't get the suspension.
But it is well worth the effort.
1. provides much more exposure to the beads when suspended.
2. You can run a lot of Purigen.
3. Very easy to service the unit.
My next reactor is going to be one of these
http://s1219.photobucket.com/user/ps...?sort=4&page=1