Etss basically said i just need 2500gph at 10 psi, and reeflo said to take one pump and feed the other pump, so the way i understood it was you take the outlet of one pump and take it to the inlet of the other. reeflo described it as 10 psi is equal to 23 feet of head pressure and with the two pumps you divide that by two.a barracuda will pump 2700 at 12 feet, so the way they described it is that i should have roughly 2700 gph at 10 psi with the two pumps. all i can do is try it and see since i already have the pumps on the way