gsmith954:
The freetronic link looks good, but the code was only for 1 flow meter ?
Correct, that's all most of us use, but I imagine more is just more of the same. There was a recent thread on using more than one.
I don't think there is need for two Megas. The principle reason for having one is the display but that display should handle all sensors. The sensing code would be essentially the same on both micros. The secondary would report in bursts to the main when the display is updated.