Please recommend return pump for my 40b and manifold

[sinful]

Tank is a 40b with 1" drain. Sump is a custom trigger systems. I created my manifold by t'ing off my return(which is 3/4). The manifold is all 1/2" and will be feeding chiller that also returns to display. Also have a valve in manifold for a reactor that will be running biopellets. My current pump does not provide much flow back to tank from chiller and its needing 100-200gph. I don't have anything going to reactor yet. Pump is a tunze silent 636gph. Head to tank is 4'.

Thinking a mag 9.5 would provide all the flow I need, but do you think it would be to much? Your suggestions?

 

[jzdad]

This is always tricky .use the calcalator
http://reefcentral.com/index.php/head-loss-calculator
and it is always better to have more flow than you need ,you can tee it back to the sump

 

[sinful]

Thanks, the calculator is good...however it doesn't account for the 1/2" manifold breaking off the return line