Balance Tank Question

[scudman]

I am in the process of designing, building a 15K gal, rectangular salt pool. I have been working on the piping schematic and have come up with the drawing below. This will be a 'overflow edge' type pool on all sides. My question is in regard to the balance tank. It seems, from my research that the water from the mains can either go to the balance tank or to the pump, but I cannot find any answers as to which is preferable or any reasons why one way is better than the other.
[attachment=0:1eocwf23]Pool pipe schematic.pdf[/attachment:1eocwf23]

 

[JasonLion]

Generally all drain & overflow water goes to the balance tank, and the pump draws water from the tank.

 

[scudman]

Generally all drain & overflow water goes to the balance tank, and the pump draws water from the tank.

OK, so then to maintain a 75% to 25% ratio of water draw between overflow and main drain I would need to have a ball valve/flow meter in the line from the MD to the BT, correct?

 

[JasonLion]

You can't maintain a 75% to 25% ratio, you just design the system to average somewhere around there. Generally the overflow goes directly into the tank, while the main drain is gated by a float valve (shut off when the tank is full).