Ca Reactor Flow Diagram and Questions

[newsalt]

I'm going to be building a Calcium Reactor soon. To make sure I got the flow path correct, I developed this flow diagram.

http://reefcentral.com/gallery/data/579/49381CALCIUM_REACTOR.jpg

I just wanted to know if I got it right. Do I have all the valves I need? I'm I missing any components?

I have a few questions about the operation:

I've read that the pH coming out of the 1st stage should be about 6.5. What should the pH coming out of the 2nd stage be? How does the display tank water stay at 8.2 if the pH out of the 1st stage is so low? How does it get back up?

Is the feed pump in the sump always running or is it used just to fill the reactors with water?

What type of pump should I use for the Recirculation Pump?

Thanks

[old salty]

Everything looks to be in order. Don't worry about pH in the reactor - you should be aiming to maintain tank parameters. If the pH is 6.8 or 7.6 coming out of the reactor, it is what it is; an arbitrary number.

Feed pump is always running. Since the output is rather low on a Ca reactor, use a small pump.

Eheim is an excellent choice for a recirculation pump.