You could probably use a Y valve with shut-offs and control the flow with them but for the extra $50 for another pump I'd use two. Ideally, if I remember correctly, the tanks should fill in 6-8 minutes if you're going to pump water into them, for the longest lasting bait.
Thanks Alex! I think your right two pumps is the way to go...
What kind of bait are you using. If it's shrimp or another hardy bait like pin-fish, then one 750 gph pump will do for both live-wells. If you are keeping white-bait or something similar, then you might need a larger pump.
To give you an idea. I have two live-wells. Both are about 20 gals. and one 1100 gph pump supplies enough water to keep white-bait, which are pretty fragile baits.
You could install one pump, then use a "Y" to supply both live-wells. Inside the live-well, install a 3/4" fitting with a barbed end to attach to the hose and a threated end to attach a shut-off valve. If you only need one live-well, just close the valve inside the live-well. This the method I use. It's cheap and effective. Here's an example of the shutoff. http://customlivewells.com/accessories.aspx
Last edited by SCFD rtrd.; 04-20-2012 at 12:39 PM.