If you add a bix in parallel to the lytron unit, you'll considerably lessen the flow through it, at which point it'll make you wonder why it's even in the loop. It's really too bad.
Now do you really want to fork out $100 for a pump? I guess you don't have a choice, do you?
Note: the 1200 is spec'ed: 6.4" L x 4.5" W x 4.6" High. 3/4" FNPT intake and 3/4" MNPT discharge.
Here's a nice little chart for it:
http://www.aquadirect.com/catalog/pu...rflowchart.htm
(Change the chart to a "line" type, to see it better).
The 1200 deadheads at 15 feet.
With the 6320 alone, I'm guesstimating that you'll achieve a flow rate of about 2 gpm (120 gph), which, with the Caravel fan, will dissipate 140 W/deg C.
So if your total heatload is 140 Watts, then the water temp will rise by one degree over ambient (theoretically).
At 0.5 gpm, that rad will dissipate about 85 Wattsa/deg C.