Hey Plum70rt,
After our chat about phosphates & sponges, I went out and got some phosphorus-zapping stuff. I found Phos-Zorb by Aquarium Pharmeceuticals (Doc Wellfish), which I chose the Phos-Zorb because it was packaged in a little pouch, which was ideal for my set up. I put it into the chamber of my biowheel in place of the mechanical filter/charcoal pad. I left it in for about a week (don't have my log handy) and my phosphates went from rather high (again, no log handy, LOL) to 0.1 .
So that's my story!
~D~