Over flow rating

[Frickmiester]

Ok I was thinking it said have one on the main line but not the return line

 

[SaltwaterNuB]

What size is the overflow hole? Also what size is the overflow pipe that youll be using? I used a 1.5" overflow with a mag 950 return pump. I had about 4 feet of head pressure. I installed ball valves and unions on my overflow pipe and return pipe.