Anybody tried a gravity feed set-up for circulation?

[MitchM]

I'm setting up a couple of tanks, one upstairs, one down plus a sump and I'm thinking of using the outflow from the upstairs tank to provide circulation for the downstairs tank before the water goes to the sump which will contain the skimmer/heaters/circulation pumps.
Has anybody else tried this? Would it be too much pressure?
The upstairs tank will have to have a closed loop for it's circulation, and I'm going to have to provide some turnover with a head pressure of probably 12 - 14 feet.

Thanks,
Mitch