I ended up using a sicce adv 7.0 return pump and connected it to the manifold. This pump just fits the width of the rear chamber and provides enough flow to power all the rear “power heads” close to the original sicce pumps. I was also able to use the original tubing connected to T connectors. I used schedule 80 but could have easily used regular pvc for this project. I’ve been very pleased with this mod and would do it again.