Right now, in the center is just a piece of foam in the middle chamber. I plan on leaving the top empty, because my kalk top off and chiller output end up in the top compartment. Yes, that is the Tunze 9002. PM me with you email and I can email you some more photos. I turned the output of the CPR past 90 degrees and added a 1 1/2" barbed elbow to direct the flow into the right heater chamber. The input side I added vinyl tubing to put the CPR pump just about on top of the JBJ pump, so I have enough room for my top float switches...