Need help with overflow box

[StirCrazy]

if you cut your slots the water hight will depend on the flow into the tank.. low flow the water level will be at the bottom of the slots.. if you rais the flow the higher it will be as the slots can only handle a spivific volume so the higher the flow the more of the slot is needed..
you could add up the area of the slots and make them to a specific amout of square inches.. for example 8 slots that are 1 inch deep and 1/8th of a inch wide will give you almost the same flow as a hole that is 1" square..

Hope this helps

Steve