mag drive 3

Can I use this one rated at 350 gph for a return with a hob overflow rated at 300 ?

 

It may be rated at 350 but after the elbow and height(depending on stand size), you will be well under 300 gph.

 

There will be 4 ft. from return pump to display tank. So the pump should not be too much stronger than the overflow? I'm still trying to figure out which pump to get.

 

What size is the tank in question?

 

30 tall

 

Yes you should be good.

 

Mag 3 is rated for 270gph, at 4'. So, you said you're going up 4'? You should be good. Elbows and bends will reduce this further. Also, if you want, you can always add a ball valve.