Doing a few searches on google puts the mag drive 12 At 1200 GPH
A 1" PVC
overflow is about 600 GPH
, so hypothetically 2 1" overflows would put you at a good spot.
However, how much head your pump has and how man turns you overflow plumbing takes and how far it travels is a factor. Do a little research on overflow GPH
and compare it to your set up. There are also calculators for this, since it is fairly different for each set up. A good plan is to set up a gate or ball valve on your overflow and return lines so you can fine tune the flow