Calculating piston mass, for transfering fluid through a length of pipe

I must clarify that I am not an engineer and I am not an engineering student. I am only doing a personal project in which I am stuck for months with the following problem, since my knowledge is not enough to answer it on my own! So I appeal to you:

Issue:

You have the following system:

As can be seen in the drawing, what is sought is to transfer the blue fluid (water) to tank 2. For this the device consists of two very heavy pistons that will be used to transfer the fluid to tank 2.

The question is this: what weight must the pistons have to transfer water to tank 2 in a certain time? What equations should I use?

All the data is in the drawing.

• So pressure is density * gravity * height , balance the piston mass and the height of its column of water against the height on the right... – Solar Mike Jul 20 '18 at 5:12
• The geometry will supply the pressure and the friction of the pistons and the flow will set the speed. – KalleMP Jul 20 '18 at 21:46

You can solve this problem by dividing the problem in three parts. We can consider Bernouli's equation for the horizontal parts, and for the vertical one we can use the formula $P = \rho \cdot g \cdot h$.