Hello,
No, you put Zeo Mix on bottom, AF Carbon right on top of it, and I use a sponge in between AF Carbon then place Phosphate Minus. I prepare medias night before exchange. I soak Zeo Mix in RODI, then before placing in reactor rinse a few times. I use stainless steel bowls for soaking. I also use near boiling RODI and pour over the AF Carbon night before to soak, again rinsing a few more times before going in reactor. I then place Zeo Mix in, then Carbon, then sponge, then AF Phosphate Minus. I then use about a liter of RODI and pour over the phoshpate minus and rinse until most brown goes away. Then off to the sump it goes. I know this may seem tedious, but have not had a problem using this way since almost a year running the program. Cheers