I'm running a small (600gph) pump for my different reactors with a manifold. The calcium reactor is the last in the line to minimize pressure.
I think the input for the reactor is 1/4? It comes with an adapter to go from 1/2 to 1/4. The output is 1/4 also. I found an adapter to go from 1/4 to airline tubing. I then put an airline valve in the airline tubing to get a steady drip rate.
Make sure you "burp" the reactor when you set it up. Run the water without restrictions on the end to get all the air out. This takes a bit of time, I ran mine like that for a day to get the air out and to check for leaks.
When I say I'm running it off a manifold you still need to use the recirculating pump (mag-5) that is installed on the base. I just use the manifold to feed the reactor. If your pump is loud or not working just get a hold of Jeff at lifereef and he can set you up with a new one.