if you are still looking for flow rates you need to say if this is for freshwater or salt, the pressure at the input and output (which is usually atmospheric but your output looks like it is P = rho*g*h) h being height the output is from the water surface. then finally the diameter of the tubes connecting the output to the sump. then you can just use Bernoullis equation and the continuity equation to figure out the flow rates (bernoullis equation is very good approximations, not exact though, but i won't get into that).
Bernoullis ---> P1 + (1/2)rho * V1 + gamma * Z1 = P2 + (1/2)rho * V2 + gamma * Z2
P = pressure
rho = density
V = Velocity of water (for V1 assume large tank and sump pump refills therefore the V1 = 0) your looking for V2
gamma= rho * g
g= 9.81 m/s^2
Z = height, you just need to decide on a reference point, any reference point will work
then the continuity equation is Q = A1 * V1 = A2 * V2 = Ax * Vx
Q = flow rate
A = area water is flowing thru
V = Velocity of water flow
since you found V2 above and you can measure and calculate A2 just use Q = A2 * V2 and with some unit conversion you should be able to get the flow rate in gal/hr
Bernoullis ---> P1 + (1/2)rho * V1 + gamma * Z1 = P2 + (1/2)rho * V2 + gamma * Z2
P = pressure
rho = density
V = Velocity of water (for V1 assume large tank and sump pump refills therefore the V1 = 0) your looking for V2
gamma= rho * g
g= 9.81 m/s^2
Z = height, you just need to decide on a reference point, any reference point will work
then the continuity equation is Q = A1 * V1 = A2 * V2 = Ax * Vx
Q = flow rate
A = area water is flowing thru
V = Velocity of water flow
since you found V2 above and you can measure and calculate A2 just use Q = A2 * V2 and with some unit conversion you should be able to get the flow rate in gal/hr
